Taxiway Overflight

Air Canada Flight 759

Airbus A320-211, C-FKCK

San Francisco, California

July 7, 2017

Incident Report

NTSB/AIR-18/01

PB2018-101561 National 

Transportation 

Safety Board
NTSB/AIR-18/01

PB2018-101561

Notation 58387

Adopted September 25, 2018

Aircraft Incident Report 

Taxiway Overflight

Air Canada Flight 759

Airbus A320-211, C-FKCK

San Francisco, California

July 7, 2017

National 

Transportation 

Safety Board

490 L’Enfant Plaza, S.W.

Washington, DC 20594
National Transportation Safety Board. 2018. Taxiway Overflight, Air Canada Flight 759, Airbus 

A320-211, C-FKCK, San Francisco, California, July 7, 2017. NTSB/AIR-18/01. Washington, DC.

Abstract: This report discusses the July 7, 2017, incident involving Air Canada flight 759, an Airbus 

A320-211, Canadian registration C-FKCK, which was cleared to land on runway 28R at San Francisco 

International Airport, San Francisco, California, but instead lined up with parallel taxiway C. Four air 

carrier airplanes were on taxiway C awaiting clearance to take off from runway 28R. The incident airplane 

descended to an altitude of 100 ft above ground level and overflew the first airplane on the taxiway. The 

incident flight crew initiated a go-around, and the airplane reached a minimum altitude of about 60 ft and 

overflew the second airplane on the taxiway before starting to climb. None of the 5 flight crewmembers 

and 135 passengers aboard the incident airplane were injured, and the incident airplane was not damaged. 

Safety issues identified in this report include the need for consistent flight management system autotuning 

capability within an air carrier’s fleet, the need for more effective presentation of flight operations 

information to optimize pilot review and retention of relevant information, the need for airplanes landing 

at primary airports within Class B and Class C airspace to be equipped with a system that alerts pilots when 

an airplane is not aligned with a runway surface, the need for modifications to airport surface detection 

equipment systems to detect potential taxiway landings and provide alerts to air traffic controllers, the need 

for a method to more effectively signal a runway closure to pilots when at least one parallel runway remains 

in use, and the need for revisions to Canadian regulations to address the potential for fatigue for pilots on 

reserve duty who are called to operate evening flights that would extend into the pilots’ window of circadian 

low. As a result of this investigation, the National Transportation Safety Board makes safety 

recommendations to the Federal Aviation Administration and Transport Canada.

The National Transportation Safety Board (NTSB) is an independent federal agency dedicated to promoting aviation, 

railroad, highway, marine, and pipeline safety. Established in 1967, the agency is mandated by Congress through the 

Independent Safety Board Act of 1974 to investigate transportation accidents, determine the probable causes of the 

accidents, issue safety recommendations, study transportation safety issues, and evaluate the safety effectiveness of 

government agencies involved in transportation. The NTSB makes public its actions and decisions through accident 

reports, safety studies, special investigation reports, safety recommendations, and statistical reviews.

The NTSB does not assign fault or blame for an accident or incident; rather, as specified by NTSB regulation, 

“accident/incident investigations are fact-finding proceedings with no formal issues and no adverse parties ... and are 

not conducted for the purpose of determining the rights or liabilities of any person.” 49 C.F.R. § 831.4. Assignment 

of fault or legal liability is not relevant to the NTSB’s statutory mission to improve transportation safety by 

investigating accidents and incidents and issuing safety recommendations. In addition, statutory language prohibits 

the admission into evidence or use of any part of an NTSB report related to an accident in a civil action for damages 

resulting from a matter mentioned in the report. 49 U.S.C. § 1154(b).

For more detailed background information on this report, visit 

https://www.ntsb.gov/investigations/SitePages/dms.aspx and search for NTSB incident ID DCA17IA148. Recent 

publications are available in their entirety on the Internet at http://www.ntsb.gov. Other information about available 

publications also may be obtained from the website or by contacting:

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Records Management Division, CIO-40

490 L’Enfant Plaza, SW

Washington, DC 20594

(800) 877-6799 or (202) 314-6551

Copies of NTSB publications may be downloaded at no cost from the National Technical Information Service’s 

National Technical Reports Library at https://ntrl.ntis.gov/NTRL/ (this product is product number PB2018-101561). 

For additional assistance, contact:

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5301 Shawnee Rd.

Alexandria, VA 22312 

(800) 553-6847 or (703) 605-6000
NTSB Aircraft Incident Report

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Contents

Figures........................................................................................................................................... iii

Tables............................................................................................................................................ iv

Abbreviations .................................................................................................................................v

Executive Summary................................................................................................................... viii

1. Factual Information...................................................................................................................1

1.1 History of Flight.........................................................................................................................1

1.1.1 Preceding Arrival on Runway 28R..................................................................................9

1.1.2 Airplanes on Taxiway C................................................................................................10

1.2 Personnel Information..............................................................................................................10

1.2.1 The Captain....................................................................................................................10

1.2.2 The First Officer ............................................................................................................12

1.3 Airplane Information ...............................................................................................................13

1.4 Airport Information..................................................................................................................14

1.4.1 Air Traffic Control Tower Staffing ...............................................................................18

1.4.2 Air Traffic Control Tower Equipment...........................................................................20

1.5 Tests and Research...................................................................................................................22

1.5.1 Airplane Performance Study..........................................................................................22

1.5.2 Enhanced Ground Proximity Warning System Simulation...........................................25

1.6 Organizational Information......................................................................................................26

1.6.1 Descent, Approach, and Arrival Information ................................................................26

1.6.2 Crew Resource Management.........................................................................................28

1.6.3 Fatigue Information .......................................................................................................29

1.6.4 Event Reports.................................................................................................................29

1.6.5 Plan Continuation and Expectation Bias Training.........................................................31

1.6.6 Flight Information..........................................................................................................32

1.7 Additional Information ............................................................................................................36

1.7.1 Wrong Surface Landings Video ....................................................................................36

1.7.2 Safety Alert for Operators .............................................................................................36

1.7.3 Canadian Fatigue Regulations.......................................................................................37

2. Analysis.....................................................................................................................................39

2.1 Introduction..............................................................................................................................39

2.2 Incident Sequence ....................................................................................................................40

2.2.1 Notification of Runway 28L Status...............................................................................40

2.2.2 Preparations for the Descent..........................................................................................40

2.2.3 Initial Approach.............................................................................................................42

2.2.4 Final Approach Segment and Go-Around .....................................................................43

2.2.5 Crew Resource Management Breakdown .....................................................................45

2.3 Reasons for Flight Crew’s Misalignment With Taxiway C.....................................................47
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2.3.1 Flight Crew Awareness of Runway Closure .................................................................47

2.3.2 Role of Expectation Bias...............................................................................................49

2.3.2.1 Initial Taxiway Misalignment..........................................................................49

2.3.2.2 Flight Crew Recognition of Misalignment ......................................................51

2.3.3 Role of Flight Crew Fatigue ..........................................................................................52

2.3.4 Mitigations to Overcome Expectation Bias...................................................................55

2.4 Reporting of the Incident Flight...............................................................................................58

2.5 Air Traffic Control Services....................................................................................................59

2.5.1 Air Traffic Control Tower Midnight Shift Staffing.......................................................59

2.5.2 Airport Surface Surveillance Capability System...........................................................61

2.6 Runway Closure Markers ........................................................................................................63

3. Conclusions...............................................................................................................................66

3.1 Findings....................................................................................................................................66

3.2 Probable Cause.........................................................................................................................68

4. Recommendations....................................................................................................................69

Board Member Statements.........................................................................................................71

5. Appendixes ...............................................................................................................................76

Appendix A: Investigation.............................................................................................................76

Appendix B: Air Canada Postincident Actions .............................................................................77

References.....................................................................................................................................78
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Figures

Figure 1. ACA759 track over SFO. ................................................................................................6

Figure 2. Incident airplane. ...........................................................................................................14

Figure 3. SFO layout map.............................................................................................................15

Figure 4. Illustration of SFO’s lighting configuration. .................................................................16

Figure 5. ASSC display at SFO. ...................................................................................................21

Figure 6. ACA759 on final approach to SFO. ..............................................................................23

Figure 7. ACA759 passing over UAL1 and relative locations of airplanes. ................................24

Figure 8. ACA759 passing over PAL115 and relative locations of airplanes. .............................24

Figure 9. Approach procedure. .....................................................................................................34

Figure 10. NOTAM showing runway 28L closure.......................................................................35

Figure 11. ATIS information Quebec. ..........................................................................................36
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Tables 

Table 1. Timeline of events.............................................................................................................8

Table 2. Captain’s self-reported sleep schedule............................................................................12

Table 3. First officer’s self-reported sleep schedule. ....................................................................13
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Abbreviations

AC advisory circular

ACA759 Air Canada flight 759

ACARS aircraft communication addressing and reporting system

agl above ground level

ASDE airport surface detection equipment

ASR air safety report

ASRS aviation safety reporting system

ASSC airport surface surveillance capability

ATC air traffic control 

ATCT air traffic control tower

ATIS automatic terminal information service

CAST Commercial Aviation Safety Team

CFR Code of Federal Regulations

CRM crew resource management

CVR cockpit voice recorder

DAL521 Delta Air Lines flight 521

EDT eastern daylight time

EGPWS enhanced ground proximity warning systems

FAA Federal Aviation Administration

FDR flight data recorder
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FMC flight management computer

FMGS flight management guidance system

FMS flight management system

IFR instrument flight rules

ILS instrument landing system

LNAV lateral navigation

LUAW line up and wait

MCDU multifunction control and display unit

msl mean sea level

NCT Northern California terminal radar approach control

nm nautical mile

NOTAM notice to airmen

NTSB National Transportation Safety Board

PAL115 Philippine Airlines flight 115

PDT Pacific daylight time

PFD primary flight display

RAAS runway awareness and advisory system

RNAV area navigation

SAFO safety alert for operators

SEA Seattle-Tacoma International Airport

SFO San Francisco International Airport
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TSB Transportation Safety Board of Canada

UAL1 United Airlines flight 1

UAL863 United Airlines flight 863

UAL1118 United Airlines flight 1118

VMC visual meteorological conditions

YYZ Toronto/Lester B. Pearson International Airport
NTSB Aircraft Incident Report

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Executive Summary

On July 7, 2017, about 2356 Pacific daylight time (PDT), Air Canada flight 759, an 

Airbus A320-211, Canadian registration C-FKCK, was cleared to land on runway 28R at 

San Francisco International Airport (SFO), San Francisco, California, but instead lined up with 

parallel taxiway C.1 Four air carrier airplanes (a Boeing 787, an Airbus A340, another Boeing 787, 

and a Boeing 737) were on taxiway C awaiting clearance to take off from runway 28R. The 

incident airplane descended to an altitude of 100 ft above ground level and overflew the first 

airplane on the taxiway. The incident flight crew initiated a go-around, and the airplane reached a 

minimum altitude of about 60 ft and overflew the second airplane on the taxiway before starting 

to climb. None of the 5 flight crewmembers and 135 passengers aboard the incident airplane were 

injured, and the incident airplane was not damaged.

2 The incident flight was operated by 

Air Canada under Title 14 Code of Federal Regulations (CFR) Part 129 as an international 

scheduled passenger flight from Toronto/Lester B. Pearson International Airport, Toronto, 

Canada. An instrument flight rules flight plan had been filed. Night visual meteorological 

conditions prevailed at the time of the incident.

The flight crewmembers had recent experience flying into SFO at night and were likely 

expecting SFO to be in its usual configuration; however, on the night of the incident, SFO parallel 

runway 28L was scheduled to be closed at 2300. The flight crew had opportunities before 

beginning the approach to learn about the runway 28L closure. The first opportunity occurred 

before the flight when the crewmembers received the flight release, which included a notice to 

airmen (NOTAM) about the runway 28L closure. However, the first officer stated that he could 

not recall reviewing the specific NOTAM that addressed the runway closure. The captain stated 

that he saw the runway closure information, but his actions (as the pilot flying) in aligning the 

airplane with taxiway C instead of runway 28R demonstrated that he did not recall that information 

when it was needed. The second opportunity occurred in flight when the crewmembers reviewed 

automatic terminal information system (ATIS) information Quebec (via the airplane’s aircraft 

communication addressing and reporting system [ACARS]), which also included NOTAM 

information about the runway 28L closure. Both crewmembers recalled reviewing ATIS 

information Quebec but could not recall reviewing the specific NOTAM that described the runway 

closure.

The procedures for the approach to runway 28R required the first officer (as the pilot

monitoring) to manually tune the instrument landing system (ILS) frequency for runway 28R, 

which would provide backup lateral guidance (via the localizer) during the approach to supplement 

the visual approach procedures. However, when the first officer set up the approach, he missed the 

step to manually tune the ILS frequency. The captain was required to review and verify all 

programming by the first officer but did not notice that the ILS frequency had not been entered.

The captain stated that, as the airplane approached the airport, he thought that he saw 

runway lights for runway 28L and thus believed that runway 28R was runway 28L and that 

 1 All times in this executive summary are PDT unless otherwise noted.

2 Similarly, no crewmembers and passengers aboard the airplanes on taxiway C were injured, and none of those

airplanes were damaged. 
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taxiway C was runway 28R. At that time, the first officer was focusing inside the cockpit because 

he was programming the missed approach altitude and heading (in case a missed approach was 

necessary) and was setting (per the captain’s instruction) the runway heading, which reduced his 

opportunity to effectively monitor the approach. The captain asked the first officer to contact the 

controller to confirm that the runway was clear, at which time the first officer looked up. By that 

point, the airplane was lined up with taxiway C, but the first officer presumed that the airplane was 

aligned with runway 28R due, in part, to his expectation that the captain would align the airplane 

with the intended landing runway. 

The controller confirmed that runway 28R was clear, but the flight crewmembers were 

unable to reconcile their confusion about the perceived lights on the runway (which were lights 

from airplanes on taxiway C) with the controller’s assurance that the runway was clear. Neither 

flight crewmember recognized that the airplane was not aligned with the intended landing runway 

until the airplane was over the airport surface, at which time the flight crew initiated a low-altitude 

go-around. According to the captain, the first officer called for a go-around at the same time as the 

captain initiated the maneuver, thereby preventing a collision between the incident airplane and

one or more airplanes on the taxiway. However, at that point, safety margins were severely reduced 

given the incident airplane’s proximity to the ground before the airplane began climbing and the 

minimal distance between the incident airplane and the airplanes on taxiway C.

The flight crewmembers stated, during postincident interviews, that the taxiway C surface 

resembled a runway. Although multiple cues were available to the flight crew to distinguish 

runway 28R from taxiway C (such as the green centerline lights and flashing yellow guard lights 

on the taxiway), sufficient cues also existed to confirm the crew’s expectation that the airplane 

was aligned with the intended landing runway (such as the general outline of airplane lights—in a 

straight line—on taxiway C and the presence of runway and approach lights on runway 28R, which 

would also have been present on runway 28L when open). As a result, once the airplane was 

aligned with what the flight crewmembers thought was the correct landing surface, they were likely 

not strongly considering contradictory information. The cues available to the flight crew to indicate 

that the airplane was aligned with a taxiway did not overcome the crew’s belief, as a result of 

expectation bias, that the taxiway was the intended landing runway.

The flight crewmembers reported that they started to feel tired just after they navigated 

through an area of thunderstorms, which radar data indicated was about 2145 (0045 eastern 

daylight time [EDT]). The incident occurred about 2356, which was 0256 EDT according to the 

flight crew’s normal body clock time; thus, part of the incident flight occurred during a time when 

the flight crew would normally have been asleep (according to postincident interviews) and at a 

time that approximates the start of the human circadian low period described in Air Canada’s 

fatigue information (in this case, 0300 to 0500 EDT). In addition, at the time of the incident, the 

captain had been awake for more than 19 hours, and the first officer had been awake for more than 

12 hours. Thus, the captain and the first officer were fatigued during the incident flight.

Cockpit voice recorder (CVR) information was not available for this incident because the 

data were overwritten before senior Air Canada officials became aware of the severity of this 

incident. Although the National Transportation Safety Board (NTSB) identified significant safety 

issues during our investigation into this incident, CVR information, if it had been available, could 

have provided direct evidence about the events leading to the overflight and the go-around. For 
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example, several crew actions/inactions during the incident flight demonstrated breakdowns in 

crew resource management (CRM), including both pilots’ failure to assimilate the runway 28L 

closure information included in the ATIS information, the first officer’s failure to manually tune 

the ILS frequency, and the captain’s failure to verify the tuning of the ILS frequency. However, 

without CVR information, the NTSB could not determine whether distraction, workload, and/or 

other factors contributed to these failures.

The NTSB identified the following safety issues as a result of this incident investigation:

• Need for consistent flight management system (FMS) autotuning capability within an 

air carrier’s fleet. The FMS Bridge visual approach to runway 28R was the only approach 

in Air Canada’s Airbus A320 database that required manual tuning for a navigational aid, 

so the manual tuning of the ILS frequency was not a usual procedure for the flight crew. 

Identifying other approaches that require an unusual or abnormal manual frequency input 

and developing an autotune solution would help preclude such a situation from recurring. 

Further, the instruction on the approach chart to manually tune the ILS frequency was not 

conspicuous during the crew’s review of the chart. An action to mitigate this situation for 

other approaches would be to ensure sufficient salience of the manual tune entry on 

approach charts.

• Need for more effective presentation of flight operations information to optimize pilot

review and retention of relevant information. The way information is presented can 

significantly affect how information is reviewed and retained because a pilot could miss 

more relevant information when it is presented with information that is less relevant. 

Although the NOTAM about the runway 28L closure appeared in the flight release and the 

ACARS message that were provided to the flight crew, the presentation of that information 

did not effectively convey the importance of the runway closure information and promote 

flight crew review and retention. Multiple events in the National Aeronautics and Space 

Administration’s aviation safety reporting system database showed that this issue has 

affected other pilots, indicating that all pilots could benefit from the improved display of

flight operations information. 

• Need for airplanes landing at primary airports within Class B and Class C airspace 

to be equipped with a system that alerts pilots when an airplane is not aligned with a

runway surface. A cockpit system that provides an alert if the system predicts a landing 

on a surface other than a runway would provide pilots with additional positional awareness 

information. Although the Federal Aviation Administration (FAA) has not mandated the 

installation of such a system, the results of a simulation showed that such technology, if it 

had been installed on the incident airplane, could have helped the flight crew identify its

surface misalignment error earlier in the landing sequence, which could have resulted in 

the go-around being performed at a safer altitude (before the airplane was dangerously 

close to other airplanes). Flight safety would be enhanced if airplanes landing at primary 

airports within Class B and Class C airspace were equipped with such a cockpit system

and/or a cockpit system that alerts when an airplane is not aligned with the specific runway 

for which it has been cleared.
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• Need for modifications to airport surface detection equipment (ASDE) systems 

(ASDE-3, ASDE-X, and airport surface surveillance capability [ASSC]) to detect 

potential taxiway landings and provide alerts to air traffic controllers. The SFO air 

traffic control tower was equipped with an ASSC system, which was not designed to 

predict an imminent collision involving an arriving airplane lined up with a taxiway; thus, 

the ASSC system did not produce an alarm as the incident airplane approached taxiway C. 

If an airplane were to align with a taxiway, an automated ASDE alert could assist 

controllers in identifying and preventing a potential taxiway landing as well as a potential 

collision with aircraft, vehicles, or objects that are positioned along taxiways. An FAA 

demonstration in February 2018 showed the potential effectiveness of such a system.3

• Need for a method to more effectively signal a runway closure to pilots when at least 

one parallel runway remains in use. A runway closure marker with a lighted flashing 

white “X” appeared at the approach and departure ends of runway 28L when it was closed.

The runway closure marker was not designed to capture the attention of a flight crew on 

approach to a different runway, and the marker did not capture the attention of the incident 

flight crew as the airplane approached the airport while aligned with taxiway C. Increased 

conspicuity of runway closure markers, especially those used in parallel runway 

configurations, could help prevent runway misidentification by flight crews while on 

approach to an airport. 

• Need for revisions to Canadian regulations to address the potential for fatigue for 

pilots on reserve duty who are called to operate evening flights that would extend into 

the pilots’ window of circadian low. The flight crew’s work schedule for the incident 

flight complied with the applicable Canadian flight time limitations and rest requirements; 

however, the flight and duty time and rest requirements for the captain (a company reserve 

pilot) would not have complied with US flight time limitations and rest requirements 

(14 CFR Part 117). Transport Canada indicated that its current flight and duty time 

regulations have been in effect since 1996. Transport Canada also indicated that it released 

a draft of proposed new flight and duty time regulations in 2014 and issued revised draft 

regulations in 2017. According to Transport Canada, the proposed regulations would better 

address the challenge of fatigue mitigation for pilots on reserve duty who are called to 

operate evening flights extending into their window of circadian low. However, 

Transport Canada has not yet finalized its rulemaking in this area.4

 3 On March 2, 2011, the NTSB recommended that the FAA “perform a technical review of Airport Surface 

Detection Equipment—Model X to determine if the capability exists systemwide to detect improper operations such 

as landings on taxiways” (A-11-12). The NTSB also recommended that the FAA, “at those installation sites where the 

technical review recommended in Safety Recommendation A-11-12 determines it is feasible, implement modifications 

to Airport Surface Detection Equipment—Model X to detect improper operations, such as landings on taxiways, and 

provide alerts to air traffic controllers that these potential collision risks exist” (A-11-13). As discussed in section 

2.5.2, the NTSB classified these recommendations “Closed—Unacceptable Action” on September 14, 2011. 

4 Title 14 CFR Part 117, “Flight and Duty Limitations and Rest Requirements: Flightcrew Members,” described 

the window of circadian low as 0200 through 0559 (body clock time zone). 
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The NTSB determines that the probable cause of this incident was the flight crew’s 

misidentification of taxiway C as the intended landing runway, which resulted from the 

crewmembers’ lack of awareness of the parallel runway closure due to their ineffective review of 

NOTAM information before the flight and during the approach briefing. Contributing to the 

incident were (1) the flight crew’s failure to tune the ILS frequency for backup lateral guidance, 

expectation bias, fatigue due to circadian disruption and length of continued wakefulness, and 

breakdowns in CRM and (2) Air Canada’s ineffective presentation of approach procedure and 

NOTAM information.

As a result of this investigation, the NTSB makes safety recommendations to the FAA and 

Transport Canada. 
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1. Factual Information

1.1 History of Flight

On July 7, 2017, about 2356 Pacific daylight time (PDT), Air Canada flight 759 (ACA759), 

an Airbus A320-211, Canadian registration C-FKCK, was cleared to land on runway 28R at 

San Francisco International Airport (SFO), San Francisco, California, but instead lined up with 

parallel taxiway C.

1 Four air carrier airplanes (a Boeing 787, an Airbus A340, another Boeing 787,

and a Boeing 737) were on taxiway C awaiting clearance to take off from runway 28R. The 

incident airplane descended to an altitude of 100 ft above ground level (agl) and overflew the first 

airplane on the taxiway.

2 The incident flight crew initiated a go-around, and the airplane reached 

a minimum altitude of about 60 ft and overflew the second airplane on the taxiway before starting 

to climb. None of the 5 flight crewmembers and 135 passengers aboard the incident airplane were 

injured, and the incident airplane was not damaged.

3 The incident flight was operated by 

Air Canada under Title 14 Code of Federal Regulations (CFR) Part 129 as an international 

scheduled passenger flight from Toronto/Lester B. Pearson International Airport (YYZ), 

Toronto, Canada. An instrument flight rules (IFR) flight plan had been filed. Night visual 

meteorological conditions (VMC) prevailed at the time of the incident.4

The captain and the first officer reported for duty about 1640 and 1610 (1940 and 1910 

eastern daylight time [EDT]), respectively. They met at the gate and discussed that the flight’s 

departure would be delayed because the airplane to be used for the flight would be arriving at YYZ 

late (due to weather in the Toronto area).

5 They also discussed the expected weather en route and 

reviewed the flight release (also referred to as a dispatch release), which contained pertinent 

information for the flight, including notice to airmen (NOTAM) information for SFO.

One of the NOTAMs in the dispatch release indicated that runway 28L would be closed 

from 2300 that night to 0800 the next morning. During postincident interviews, both flight 

crewmembers provided different accounts regarding their awareness of the runway closure.6

During interviews about 1 week after the incident, the captain stated that he saw the NOTAM 

about the runway 28L closure in the flight release, and the first officer stated that he did a “quick 

 1 (a) All times in this report are PDT unless otherwise noted. (b) This report also refers to ACA759 as the incident 

airplane and the incident flight. (c) Title 49 Code of Federal Regulations 830.2 defined an incident as “an occurrence 

other than an accident, associated with the operation of an aircraft, which affects or could affect the safety of 

operations.”

2 All altitudes in this report are agl unless otherwise indicated. 

3 Similarly, no crewmembers and passengers aboard the airplanes on taxiway C were injured, and none of those

airplanes were damaged. 

4 Supporting documentation referenced in this report can be found in the public docket for this incident, accessible 

from the National Transportation Safety Board’s (NTSB) Accident Dockets web page by searching DCA17IA148. 

Other NTSB documents referenced in this report, including reports and summarized safety recommendation 

correspondence, are accessible from the NTSB’s Aviation Information Resources web page (www.ntsb.gov/air).

5 Flight 759 was originally scheduled to push back from the gate at 1755 (2055 EDT), take off at 1809 

(2109 EDT), and land at 2303 (0203 EDT). 

6 The NTSB interviewed the incident captain on July 14 and the incident first officer on July 18, 2017. The NTSB 

also interviewed both incident flight crewmembers on August 10, 2017. 
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scan” of the NOTAMs in the flight release but could not recall whether he had seen the runway 28L 

closure NOTAM and whether he and the captain had discussed the closure information at the gate. 

The first officer also stated that he realized, after the incident flight landed, that runway 28L had 

been closed. During an interview about 1 month after the incident, the captain stated that he and 

the first officer had discussed the runway 28L closure while at YYZ but that they did not place

much emphasis on that information because, at that time, the flight was scheduled to land at SFO 

before the runway would be closed. (The National Transportation Safety Board [NTSB] notes that 

the flight was originally scheduled to land at SFO at 2303, 3 minutes after runway 28L was 

scheduled to be closed.)

The airplane pushed back from the gate at YYZ at 1825 (2125 EDT), 30 minutes later than 

originally scheduled. The captain was the pilot flying, and the first officer was the pilot monitoring.

Flight data recorder (FDR) data showed that the throttles were advanced to the takeoff power 

setting about 1858 (2158 EDT) and that the autopilot was engaged shortly after takeoff and 

remained engaged until just before the final approach to SFO.7 The flight crewmembers reported 

that the departure, climb, cruise, and descent phases of flight were uneventful except for an area 

of thunderstorms about midway through the flight.

8 The crewmembers also reported that they 

started to feel tired just after they navigated through the thunderstorms, which radar data indicated 

was about 2145 (0045 EDT).

Before the airplane began its descent into the terminal area, the first officer obtained 

automatic terminal information service (ATIS) information Quebec via the airplane’s aircraft 

communication addressing and reporting system (ACARS) and printed the information.9

(Air Canada records indicated that, about 2321, the airplane was sent the ACARS message with 

the ATIS information.) Among other things, ATIS information Quebec indicated, “Quiet Bridge 

visual approach in use,” “landing runway 28R,” and “NOTAMS...runways 28L, 10R closed.”

(SFO lighting logs indicated that the lights on runway 28L were turned off about 2312.) ATIS 

information Quebec also indicated that the runway 28L approach lighting system and the 

runway 28L/10R centerline lights were out of service. During postincident interviews, the flight 

crewmembers recalled reviewing ATIS information Quebec but could not recall whether they saw 

the ATIS-reported information about the runway 28L closure.

 7 The airplane was equipped with a Honeywell solid-state FDR, model 980-4700-042, that was required by 

14 CFR 129.20 to record 34 parameters and 25 hours of data. The FDR recording contained about 108 hours of data, 

including 5 hours 15 minutes from the incident flight. The FDR recording for the incident flight began about 1835 

(2135 EDT). The airplane was also equipped with a Honeywell solid-state cockpit voice recorder (CVR), model 

980-6022-001, but the data from the incident flight were overwritten before Air Canada was notified about this 

incident. (This CVR model was designed to record 2 hours of operational data, which was consistent with the 

requirements of 14 CFR 129.5 and International Civil Aviation Organization Annex 6 for CVRs to retain the 

information recorded during at least the last 2 hours of their operation.) Section 1.6.4 discusses notification events for 

this incident.

8 During a postincident interview, the captain stated that it was “stressful” navigating through the area of 

thunderstorms. 

9 Air Canada allowed flight crews to obtain ATIS information using ACARS or VHF communications.
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ATIS information Quebec also included weather information.10 Given this information and 

the reported landing runway in use, the captain briefed Air Canada’s Flight Management System 

(FMS) Bridge visual approach procedure to SFO runway 28R.11 The FMS Bridge visual approach 

to runway 28R, coded as the area navigation (RNAV) 28R approach, was a commercial airline 

overlay chart (a Jeppesen chart customized for Air Canada) based on the Quiet Bridge visual 

approach procedure to runway 28R.12

Air Canada’s FMS Bridge visual approach procedure to runway 28R required pilots of 

Airbus A319/A320/A321 airplanes to manually enter (tune) the instrument landing system (ILS) 

frequency into the airplane’s flight management computer (FMC) to provide backup lateral 

guidance (via the localizer) to the runway.

13 The FMS Bridge visual approach to runway 28R was 

the only approach in Air Canada’s Airbus A320 database that required manual tuning for a 

navigational aid.14 As part of his pilot monitoring duties, the first officer would have used the 

multifunction control and display unit (MCDU) to program required settings, but he did not enter 

the ILS frequency into the radio/navigation page. The first officer reported, during a postincident 

interview, that he “must have missed” the radio/navigation page and was unsure how that could 

have happened. Also, the captain did not verify, during the approach briefing, that the ILS 

frequency had been entered, and neither flight crewmember noticed that the ILS frequency was 

not shown on the primary flight displays (PFD).15 FDR data showed that the ILS frequency was 

not tuned and that no frequency had been entered. 

As part of the approach briefing, Air Canada’s procedures required the flight crew to 

discuss any threats associated with the approach. The captain stated that they discussed as threats 

the nighttime landing, the traffic, and the busy airspace. The captain also reported that he and the 

first officer discussed that “it was getting late” and that they would need to “keep an eye on each 

other.” The first officer stated that the threats were the mountainous terrain, the nighttime

 10 ATIS information Quebec included the automated surface observing system weather information recorded at 

2256. The ATIS information indicated the following: wind was from 310° at 12 knots, visibility was 10 statute miles, 

sky was clear, temperature was 17°C (63°F), dew point was 9°C (48°F), and altimeter was 29.93 inches of mercury. 

The automated surface observing system weather information at 2356 (the time of the incident) indicated the 

following: wind was from 290° at 9 knots, visibility was 10 statute miles, sky was clear, temperature was 16°C (61°F), dew point was 9°C (48°F), and altimeter was 29.92 inches of mercury.

11 The approach briefing is the first item on Air Canada’s pre-descent checklist.

12 Figure 9 in section 1.6.6 shows the approach chart. 

13 According to the Federal Aviation Administration’s (FAA) Aeronautical Information Manual, section 1-1-9, ILS ground equipment consists of two “highly directional transmitting systems,” one of which is the localizer, which 

provides course guidance to the runway centerline. Air Canada’s chart for the FMS Bridge visual approach to 

runway 28R showed the ILS frequency (111.7) in the plan view. The Jeppesen chart for the ILS or localizer approach 

to runway 28R showed 111.7 as the localizer frequency. 

14 Honeywell, the manufacturer of the Air Canada A320 FMS, stated, in e-mails dated July 19, 2018, that the 

procedure for this approach was created by United Airlines and that Air Canada used United Airlines’ database for its 

operations. The database did not include a frequency for the FMS to autotune for the approach procedure, and 

Air Canada’s policy was to make changes to the database only if information (such as waypoints and altitude 

restrictions) was not correct. Because the information that United Airlines developed for this approach did not include

a frequency for autotuning, manual tuning of the ILS was required.

15 For ILS information to appear on the PFDs, one of the incident flight crewmembers would have had to select 

the “LS” buttons on the glareshield, but neither crewmember mentioned selecting this button during the approach. 

Air Canada’s procedures for the FMS Bridge visual approach to runway 28R did not indicate that a flight crew was 

required to take this action.
NTSB Aircraft Incident Report

4

conditions, and both flight crewmembers’ alertness. The captain and the first officer could not 

recall whether they discussed the runway 28L closure during the approach briefing. 

FDR data showed that, about 2324, the selected altitude for the autopilot changed from the 

cruise altitude (flight level 360) to 8,000 ft mean sea level (msl), which was the crossing altitude 

for the first waypoint on the approach. When the airplane began its descent about 2327, the 

autopilot lateral navigation mode remained as “NAV [navigation],” and the vertical navigation 

mode changed to “DES [descent].” According to Airbus, this configuration was consistent with 

the autopilot operating in a managed descent profile.16

According to air traffic control (ATC) voice recordings, at 2330:42, the flight crew checked 

in with the Northern California terminal radar approach control (NCT) approach controller on the 

DYAMD 3 (RNAV) standard terminal arrival route to SFO.17 At that time, the airplane was 

descending from an altitude of 27,000 ft msl. 

After the flight crew’s initial contact with NCT, the controller issued instructions to join 

the FMS Bridge visual approach to runway 28R after reaching the final waypoint on the standard 

terminal arrival route. FDR data showed that, as the airplane descended through an altitude of 

about 14,500 ft msl at 2336:30, the altitude selected parameter changed to 10,944 ft msl. At 

2338:01, the autopilot lateral navigation mode changed from “NAV” to “HDG [heading]” with no

recorded corresponding change in the vertical navigation mode. According to Airbus, this 

configuration and the change in selected altitude were consistent with the autopilot operating in an 

open descent profile.18 The flight crewmembers did not discuss the descent mode during the 

approach briefing, but the first officer reported, during a postincident interview, that he perceived 

that the descent mode had switched from a managed to an open descent.

19 The first officer also 

stated that he was uncomfortable with the approach being flown in the open descent mode and that 

he did not say anything to the captain because the procedure was allowed.

20

At 2346:08, the controller instructed ACA759 to turn right direct to the TRDOW waypoint

and join the FMS Bridge visual approach to runway 28R, and the flight crew acknowledged this 

 16 Air Canada’s A319/A320/A321 Aircraft Operating Manual, volume 1, section 4, “Standard Operating 

Procedures,” indicated that, for the managed descent mode, an airplane is guided along the FMS lateral and vertical 

flight plan and speed profile. For more information about this descent mode, see section 1.6.1. 

17 The NTSB determined the time and content of air/ground transmissions referenced in this report using certified 

FAA audio recordings of NCT and SFO air traffic control tower communications.

18 Air Canada’s A319/A320/A321 Aircraft Operating Manual indicated that, for the selected descent mode (also 

referred to as the open descent mode), an airplane is guided by targets that the pilot flying selects and enters into the 

flight control unit. For more information about this descent mode, see section 1.6.1. According to FDR data, between 

the altitudes of 8,040 and 1,456 ft msl, the airplane could have been operating in either the open descent mode or the 

managed descent mode without altitude constraints.

19 In an e-mail dated March 23, 2018, the captain stated the following about the descent mode: “The descent 

initially was flown in selected [open mode] to catch up with the profile...[in] part due to the [air traffic] controller 

taking us out of the normal approach and due to radar vectoring. Once I was comfortable that the airplane, and the 

automation was caught up with the FMC, and the profile, the rest of the approach was flown in Managed mode as per 

the profile published on the approach plate.” The NTSB notes that situations that might warrant the use of the open 

descent mode include vectoring off the approach (which occurred during the incident flight), maintaining a specific 

altitude that is above the glidepath until reaching a specific intersection, and descending to a certain altitude that is 

below the projected calculated glidepath. 

20 According to Air Canada, the procedure was allowed until reaching the final waypoint on the approach. 
NTSB Aircraft Incident Report

5

instruction.

21 At 2346:19, the controller asked the crewmembers if they had the airport or bridges 

in sight; the flight crew replied that the bridges were in sight. At 2346:30, the controller cleared 

the airplane for the approach and, at 2350:48, instructed the flight crew to contact the SFO air 

traffic control tower (ATCT).

At 2351:07, the flight crew contacted the SFO ATCT and advised that the airplane was on 

the FMS Bridge visual approach to runway 28R. Four seconds later, the tower controller issued a 

landing clearance for runway 28R.

22 The flight crew acknowledged the landing clearance at 

2351:18. FDR data showed that the landing gear was selected to the down position at 2352:46. 

Air Canada’s FMS Bridge visual approach procedure to runway 28R indicated that pilots 

of Airbus A319/A320/A321 airplanes were to do the following: “at or before F101D [the final 

waypoint on the approach], disengage autopilot and continue as per Visual Approaches [standard 

operating procedures].” FDR data showed that the autopilot was disconnected at 2353:28 when 

the airplane was at an altitude of 1,300 ft and that the flight directors were disengaged at 2354:02 

when the airplane was at an altitude of 1,200 ft. The airplane passed F101D at 2354:28, when the 

airplane was at an altitude of about 1,100 ft, and the captain made the required 14° right turn to 

align the airplane with runway 28R but instead aligned the airplane with taxiway C. 

During a postincident interview, the first officer reported that, during the approach, he was 

looking inside the cockpit to accomplish his tasks as the pilot monitoring. For example, after the 

autopilot was disconnected, the first officer set the missed approach altitude and heading in case a 

missed approach was necessary; the first officer stated that he had to look at the approach chart to 

obtain that information. Also, the first officer reported that the captain had asked him to set the 

heading bug (indicator) to the runway heading. The first officer stated that he had difficulty finding 

the heading information on the approach chart, so he had to reference the airport chart.23 The 

captain reported that he saw lights across what he thought was the runway 28R surface. The captain 

asked the first officer to find out whether the runway was clear, at which time the first officer 

looked outside the cockpit. The first officer stated that the captain’s request occurred between the

time that the airplane passed F101D (at an altitude of about 1,100 ft) and the time that the airplane 

descended to an altitude of 600 ft.

The ATC voice recording indicated that, at 2355:45, the flight crew made the following 

transmission to the controller: “Just want to confirm, this is Air Canada seven five nine, we see 

some lights on the runway there, across the runway. Can you confirm we’re cleared to land?”24 At 

that time, the airplane was passing through an altitude of 300 ft. During a postincident interview, 

the controller stated that, just before the query about the status of runway 28R, he had visually 

scanned the runways from the departure to approach ends. The controller also stated that, in 

 21 Once the airplane joined the approach, the autopilot lateral navigation mode changed to “NAV.”

22 The tower controller was working all positions in the ATCT at that time. Section 1.4.1 discusses ATCT staffing 

on the night of the incident. 

23 FDR data indicated that the missed approach altitude and the runway heading were set at 2355:00.

24 The captain stated, during a postincident interview, that it took “a while” for the first officer to contact the 

controller because of “chatter” on the tower frequency. The ATC voice recording showed that, during the 61 seconds 

before the flight crew’s query to the controller, there were ongoing communications between the tower and airplanes 

on the ground. 
NTSB Aircraft Incident Report

6

response to the query, he checked the radar display and the airport surface surveillance capability 

(ASSC) display and then rescanned runway 28R. Regarding the ASSC display, the controller 

reported that he saw the ACA759 data symbol just to the right of the runway centerline, which he 

stated was normal for the FMS Bridge visual approach to runway 28R.

At 2355:52, 1 second after the flight crew completed its transmission, the controller replied, 

“Air Canada seven five nine confirmed cleared to land runway two eight right. There’s no one on 

runway two eight right but you.”25 About that time, the airplane was passing through an altitude 

of 200 ft and was 2,300 ft (0.38 nautical mile [nm]) from the seawall that protected the airfield 

from San Francisco Bay.

26 At 2355:58, the flight crew acknowledged the transmission; about that 

time, the airplane was 500 ft (0.08 nm) from the seawall. Figure 1 shows ACA759’s track before 

reaching the seawall along with the extended centerlines for runway 28R and taxiway C.

Figure 1. ACA759 track over SFO. 

Note: (a) This figure shows a plot of data and does not depict information that was available to the pilots and controller. 

(b) The range shown at the bottom of the figure is the distance from/beyond the airport seawall. 

 25 At this time, the ACA759 data symbol (which showed only the airplane’s call sign) disappeared from the ASSC 

display because the airplane was no longer in the system’s depiction area (coverage cone). The ASSC display showed

the ACA759 data symbol again 12 seconds later, at 2356:04. For more information about the ASSC system, see 

section 1.4.2.

26 The seawall was about 650 ft from the runway 28R displaced threshold and about 400 ft from the paved surface 

of taxiway C. Because taxiway C did not have a defined threshold (the taxiway curved when intersecting runway 28R), 

the seawall located before the approach ends of runways 28R and 28L was used to reference distances during the 

incident airplane’s approach to taxiway C.
NTSB Aircraft Incident Report

7

The ATC voice recording also indicated that, at 2355:59, another pilot stated on the tower 

frequency, “where is that guy going?”27 The voice on the transmission was later identified as that 

of the captain from the first airplane on taxiway C, United Airlines flight 1 (UAL1). About that 

time, ACA759 was still 500 ft (0.08 nm) from the airport seawall and at an altitude of 150 ft while 

lined up with taxiway C. At 2356:03 (after ACA759 crossed the seawall), ACA759 overflew 

UAL1 at an altitude of 100 ft; about the same time, the UAL1 captain stated, over the tower 

frequency, “he’s on the taxiway.” About the same time as the UAL1 captain’s second transmission, 

the flight crew from the second airplane on taxiway C, Philippine Airlines flight 115 (PAL115), 

turned on that airplane’s landing gear and nose lights, illuminating a portion of the taxiway and 

the UAL1 airplane.

FDR data showed that, at 2356:05, the throttles on ACA759 were advanced, and the 

airplane’s engine power and pitch increased. At that time, the airplane was at an altitude of about 

89 ft.28 During a postincident interview, the captain stated that, as the airplane was getting ready 

to land, “things were not adding up” and it “did not look good,” so he initiated a go-around.29 The 

captain reported that he thought that he saw runway lights for runway 28L and believed that 

runway 28R was runway 28L and that taxiway C was runway 28R.30 During a postincident 

interview, the first officer reported that he thought that he saw runway edge lights but that, after 

the tower controller confirmed that the runway was clear, he then thought that “something was not 

right”; as a result, the first officer called for a go-around because he could not resolve what he was 

seeing. The captain further reported that the first officer’s callout occurred simultaneously with 

the captain’s initiation of the go-around maneuver. 

The airplane continued descending, reaching a minimum altitude of about 60 ft at 2356:07 

as the airplane overflew PAL115. One second later, once the engines and elevators had fully 

transitioned to their go-around position, the airplane began to climb. During the 3 seconds between 

the time that the flight crew initiated the go-around and the airplane began climbing, ACA759 had 

flown about 700 ft (0.12 nm) from the location over the taxiway where the go-around was initiated.

 27 The controller stated, during a postincident interview, that the transmission seemed “out of context.” The ATC 

voice recording indicated that, 2 seconds after this transmission, the controller stated to himself, “who is...talk?” 

28 The NTSB performed an airplane performance study for this incident (see section 1.5.1), and some 

FDR-recorded altitudes were adjusted according to the results of the study. For example, the airplane’s altitude when 

the throttles were advanced was adjusted from the FDR-recorded radio altitude (which indicates the airplane’s height 

above the ground) of about 84 ft. Also, the airplane’s FDR-recorded minimum altitude of 59 ft (at 2356:07) was 

adjusted.

29 Air Canada’s Flight Operations Manual provided the criteria regarding when a go-around should be initiated. 

These criteria included “landing will not be accomplished within the touchdown zone” and “landing will not be 

accomplished on the runway centerline.” The captain stated, during a postincident interview, that he thought that the 

go-around maneuver began when the airplane was at an altitude of about 400 ft and was 0.5 nm from the runway. The 

NTSB determined the initiation of the go-around (at an altitude of 89 ft and 0.26 nm beyond the seawall) by the throttle 

lever angles, which increased from 22.5° to 42°; the engine N1 (fan speed), which increased from 57 to 94%; and the 

corresponding sidestick input as the throttles were advanced.

30 Between the time of the runway 28L closure and ACA759’s approach, nine airplanes flew the FMS Bridge 

visual approach and made uneventful landings on runway 28R. (Four airplanes were on taxiway C during that time, 

as described in this section.) The pilots of the flight that immediately preceded ACA759 reported confusion regarding 

the identification of the runway 28R surface, as discussed in section 1.1.1.
NTSB Aircraft Incident Report

8

At 2356:09, the controller instructed the ACA759 flight crew to go around.

31 The ACA759

flight crew acknowledged this instruction 2 seconds later as the airplane overflew the third airplane 

on the taxiway, United Airlines flight 863 (UAL863), at an altitude of 200 ft. Immediately 

afterward, ACA759 overflew the fourth airplane on the taxiway, United Airlines flight 1118 

(UAL1118) at an altitude of 250 ft. Both incident pilots reported (during postincident interviews) 

that they did not see any airplanes on the taxiway. Table 1 shows the events between ACA759’s 

landing clearance and overflight of taxiway C according to the airplane performance study 

conducted for this incident. 

Table 1. Timeline of events.

Event Time Distance from 

airport seawall 

Airplane altitude 

(agl) 

Tower: Cleared to land 28R. 2351:11 -11.5 nm 3,500 ft

Landing gear down 2352:46 -7.7 nm 2,000 ft

Autopilot off 2353:28 -6.0 nm 1,300 ft

Flight directors off 2354:02 -4.8 nm 1,200 ft

Passed F101D and lined up with 

taxiway C

2354:28 -3.6 nm 1,100 ft

ACA759: Confirm runway clear. 2355:45 -4,000 ft, -0.66 nm 300 ft

Tower: Confirmed clear to land. 2355:52 -2,300 ft, -0.38 nm 200 ft

ACA759: Okay. 2355:58 -500 ft, -0.08 nm 150 ft

UAL1 pilot: Where is that guy 

going?

2355:59 -500 ft, -0.08 nm 150 ft

UAL1 pilot: He’s on the taxiway. 2356:03 +450 ft, +0.07 nm 100 ft

Passed over UAL1 2356:03 +450 ft, +0.07 nm 100 ft

Throttles advanced for go-around 2356:05 +850 ft, +0.11 nm 89 ft

Passed over PAL115 2356:07 +1,250 ft, +0.21 nm 60 ft

Began climb 2356:08 +1,550 ft, +0.26 nm 89 ft

Tower: Go around. 2356:09 +1,700 ft, +0.28 nm 130 ft

Passed over UAL863 2356:11 +2,200 ft, +0.36 nm 200 ft

Passed over UAL1118 2356:12 +2,600 ft, +0.43 nm 250 ft

Note: The airplane’s distance from the seawall is expressed in feet and nautical miles for distances less than 1 nm.

At 2356:12, the controller advised the ACA759 flight crew, “it looks like you were lined 

up for [taxiway] Charlie,” and instructed ACA759 to fly a heading of 280° and climb to 3,000 ft

msl. The flight crew acknowledged the heading and altitude instructions at 2356:18. At 2356:23, 

ACA759’s landing gear was raised; 5 seconds later, the autopilot was engaged. At 2356:44 and 

2356:55, the controller instructed the flight crew to contact NCT, and the crew acknowledged the 

instruction at 2357:00. During the downwind leg for ACA759’s second approach, the first officer 

asked the captain if they should set the ILS frequency, and the captain agreed. The second approach 

to SFO was uneventful, and ACA759 made a successful landing on runway 28R about 0011 on 

July 8. The captain and first officer completed their duty periods at 0032.

 31 (a) The controller stated that, when ACA759 was about 1/10 mile on short final, he noticed that the airplane 

looked “extremely strange” regarding its proximity to taxiway C and the airplanes on the taxiway and then made the 

decision to have ACA759 go around. (b) The flight crewmembers indicated, during postincident interviews, that they 

did not hear specific transmissions on the tower frequency between the controller’s verification that the runway was 

clear and his go-around instruction.
NTSB Aircraft Incident Report

9

1.1.1 Preceding Arrival on Runway 28R

The airplane that preceded the incident airplane into SFO, a Boeing 737 operated as Delta 

Air Lines flight 521 (DAL521), landed on runway 28R about 4 minutes before the incident

occurred. During postincident interviews, both DAL521 flight crewmembers reported that, after 

visually acquiring the runway environment, they questioned whether their airplane was lined up 

for runway 28R.32 The DAL521 captain stated that he could see lights (but no airplanes) on 

taxiway C and that those lights gave the impression that the surface could have been a runway.

33

The DAL521 first officer reported seeing a set of lights to the right of runway 28R but that he 

“could not register” what those lights were. The DAL521 first officer also reported that there were 

“really bright” white lights on the left side of runway 28R (similar to the type used during 

construction), but both he and the captain knew that runway 28L was closed. 

The DAL521 flight crewmembers were able to determine that their airplane was lined up 

for runway 28R after cross-checking the lateral navigation (LNAV) guidance. The DAL521 

captain stated that, without lateral guidance, he could understand how the runway 28R and 

taxiway C surfaces could have been confused because the lights observed on the taxiway were in 

a straight line and could have been perceived as a centerline. The DAL521 crewmembers 

confirmed that their airplane was lined up correctly when they visually acquired the painted “28R” 

marking on the paved surface of the runway; they estimated that their airplane was at an altitude 

of 300 ft at that time.

34

The DAL521 captain and first officer provided written statements to Delta Air Lines (dated 

July 13 and 12, 2017, respectively) that were subsequently provided to the NTSB. The DAL521 

captain stated, “had the runway sequenced flashing lights been on it would have defined the 

landing runway or had we flown the ILS [approach] we would have had precision course guidance 

which would have eliminated the illusion that we were not lined up on runway 28R.” The DAL521 

first officer stated, “the PF [pilot flying] stayed on the LNAV guidance all the way to the runway 

which mitigated the confusion we experienced from the lighting and non-normal airport 

configuration at SFO that night.”35 Both flight crewmembers indicated that, after landing, they

heard a radio communication about an airplane lined up with the taxiway followed by the tower 

controller’s instruction for the airplane to go around, and the first officer indicated that he saw an 

aircraft lined up on the taxiway initiating a go-around. The DAL521 first officer also indicated that 

he called the ATCT about 40 to 50 minutes after the incident and suggested that, to assist pilots 

 32 Similar to the ACA759 flight crew, the DAL521 flight crew flew the FMS Bridge visual approach to 

runway 28R. 

33 The ASSC system showed that, as DAL521 approached the runway, UAL1, PAL115, UAL863, and UAL1118

were on the taxiway (in about the same positions as when ACA759 approached the runway).

34 The airplane performance study showed that, when the incident airplane reached an altitude of 300 ft, the 

airplane was 4,000 ft (0.66 nm) from the seawall, so the DAL521 airplane was most likely about the same distance 

from the seawall when the DAL521 flight crew visually acquired the painted “28R” on the runway. 

35 The DAL521 first officer also stated the following: “The construction lights were so bright we could not 

determine the location of the inboard runway, 28L. So I initially thought the construction was on a taxiway and we 

might be lined up on Rwy 28L and the taxiway on the right could be Rwy 28R.”
NTSB Aircraft Incident Report

10

with runway identification, flight crews should “fly ILS approaches to RWY 28R” or the tower 

should “turn on the lights for RWY 28L.”36

1.1.2 Airplanes on Taxiway C

The flight crews of the four airplanes that were on taxiway C at the time of the incident 

provided written statements to the NTSB. The captain of the first airplane, a Boeing 787 operated 

as UAL1, stated that he had a clear view of arriving traffic. The UAL1 captain also stated that he 

first saw ACA759 when it was about 1 to 2 miles away because ACA759’s landing lights were 

pointed directly at the UAL1 airplane. He thought that ACA759 would correct its course and align 

with the runway. When that did not occur, he transmitted “where is that guy going” and “he’s on 

the taxiway” on the tower frequency, and the controller directed the incident airplane to go around.

The flight crewmembers of the second airplane, an Airbus A340 operated as PAL115, 

stated that, when ACA759 was on short final, it became evident that the airplane was lined up with 

taxiway C. The PAL115 crewmembers also reported that they switched on their airplane’s landing 

gear lights and nose lights so that the ACA759 flight crewmembers could recognize that they had 

aligned the airplane with a taxiway. The PAL115 crewmembers further stated that the controller’s 

go-around instruction was issued after ACA759 had overflown their airplane. 

The captain of the third airplane, a Boeing 787 operated as UAL863, stated that he turned 

on all airplane lights before the ACA759 flight crew performed a go-around. The UAL863 

first officer stated that “a lot of lights” were on runway 28L and that he noticed an “X” on 

runway 28L.

37 The UAL863 first officer also stated that it “quickly became obvious” that ACA759 

was lining up with the taxiway. One of the UAL863 relief first officers (who was in the cockpit at 

the time) stated that “the tower controller should not have been the only controller working the 

entire airport” because it took him a few seconds to respond to the UAL1 pilot’s transmissions. 

The captain of the fourth airplane, a Boeing 737 operated as UAL1118, stated that he lost 

sight of ACA759 when it was at an altitude of about 500 to 600 ft because of his airplane’s position 

behind a Boeing 787. The captain also stated that, although the ACA759 flight crew “made a 

serious mistake that went unchecked for way too long,” it was also important to note that the tower 

controller “was performing way too many functions...Ground, Tower, and at times ops vehicles.”

1.2 Personnel Information

1.2.1 The Captain

The captain, age 56, held a Canadian airline transport pilot (aeroplane) license with a 

multiengine land rating. The captain’s most recent pilot’s license, dated October 2, 2015, included 

a type rating for the EA32, which is the Canadian flight crew type rating designation for 

 36 During a postincident interview, the controller stated that, after ACA759 landed, a pilot from a Delta Air Lines 

flight called the tower to report a problem differentiating runway 28R from taxiway C. 

37 The incident flight crewmembers stated that they did not see a lighted “X” on runway 28L to indicate that it 

was closed. Similarly, neither DAL521 pilot recalled seeing a lighted “X” to indicate that runway 28L was closed.
NTSB Aircraft Incident Report

11

Airbus A320-series airplanes. The captain also held a category 1 medical certificate dated 

December 20, 2016, with a limitation that required him to wear glasses.38 The captain reported 

that he was wearing his glasses at the time of the incident.

The captain was employed by Canadian Airlines between 1988 and 2000 and Air Canada 

since 2000 (after the two airlines merged). He had been a captain on the A320 since 2007. 

According to Air Canada records and information provided by the captain, he had accumulated 

about 20,000 hours of total flight experience, including about 7,063 hours in the A320, about 

4,797 hours of which were as an A320 pilot-in-command. He had flown about 166, 56, 11, and 

6 hours in the 90, 30, and 7 days and 24 hours, respectively, before the incident. The captain’s last 

line check occurred on March 8, 2017, and his last recurrent ground training occurred on 

January 20, 2017. The captain had no previous accident or incident history, and company training 

records showed that he had not failed any pilot checkrides. 

The captain reported that he had been to SFO “lots of times,” including once or twice 

during the 4 months before the incident. The captain recalled that, on previous flights into SFO, 

runways 28L and 28R were both illuminated, and he stated that he had never seen runway 28L 

“dark.” The incident flight was the first time that the captain and the first officer had flown 

together. 

72-Hour History

The captain stated that he went to sleep between 0030 and 0100 EDT on July 5, 2017, and 

awoke between 0700 and 0800 EDT. He was off from work that day. On July 6, the captain went 

to sleep about 0000 EDT and awoke about 0800 EDT. The captain was a reserve pilot for 

Air Canada, and his reserve duty period on July 6 began at 0500 EDT. He reported for duty 

between 1600 and 1700 EDT and flew to LaGuardia Airport, New York, New York, and then back 

to YYZ. He went off duty at 2313 EDT (15 minutes after the flight arrived at the gate) and then 

cleared customs, took a train to the airport parking lot, walked to his car, and drove home. He 

stated that the flight from New York, because of its arrival time, affected his sleep cycle “a little 

bit.” The captain went to sleep between 0200 and 0300 EDT on July 7 and awoke about 0745 EDT. 

The captain considered himself to be “fairly rested” during the 3 nights before the incident flight.

The captain’s reserve duty period began at 1113 EDT on July 7. About 1149 EDT, crew 

scheduling called the captain to notify him of a round-trip flight assignment from YYZ to SFO.

39

The captain did not take any naps that day and reported for duty by 1940 EDT. The captain 

considered himself to be rested before the flight but reported that he started feeling fatigued 

midway through the flight, just after the airplane maneuvered through an area of thunderstorms.

At the time of the incident, the captain had been awake for more than 19 hours. Table 2 shows the 

captain’s sleep schedule during the 72 hours before the incident. 

 38 The Transportation Safety Board of Canada reviewed both flight crewmembers’ medical certificates as part of 

this investigation and found that the captain and the first officer reported no medications, medical conditions, or sleep 

disorders as part of their category 1 medical examinations. In addition, neither flight crewmember reported any 

medications, medical conditions, or sleep disorders during postincident interviews.

39 The return flight, from SFO to YYZ, departed on July 8 at 1649 (1949 EDT) and arrived at 2135 (0035 EDT 

on July 9).
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Table 2. Captain’s self-reported sleep schedule. 

Date Bedtime (EDT) Awakening time (EDT) Sleep opportunity

July 4 to 5 Between 0030 and 0100 Between 0700 and 0800 6 to 7.5 hours

July 5 to 6 0000 0800 8 hours

July 6 to 7 Between 0200 and 0300 0745 4.75 to 5.75 hours 

The captain stated that he normally obtained between 6 and 7 hours of sleep each night and 

felt rested after that amount of sleep. He consistently went to bed after 0000 EDT and considered

himself to be neither a morning nor an evening person. The captain thought that it was “hard to 

get into a rhythm” when traveling because of difficulty winding down and falling asleep 

immediately after flights. The captain reported that he did not take any prescription or 

nonprescription medicine, use tobacco products or illicit drugs, and consume alcohol in the 

72 hours before the incident. The captain also reported no issues with his health and had no changes 

to his health, financial situation, or personal life within the 12 months before the incident that 

would have affected his performance on the day of the incident.

1.2.2 The First Officer

The first officer, age 42, held a Canadian airline transport pilot (aeroplane) license with a 

multiengine land rating. The first officer’s most recent pilot’s license, dated November 30, 2015, 

included a type rating for the EA32 (the Canadian flight crew type rating designation for Airbus 

A320-series airplanes). The first officer also held a category 1 medical certificate dated May 12, 

2017, with no limitations.

The first officer had been employed by Air Canada since December 2007. According to 

Air Canada records and information provided by the first officer, he had accumulated about 

10,000 hours of total flight experience, including about 2,343 hours in the A320 as 

second-in-command. He had flown about 148, 70, 18, and 6 hours in the 90, 30, and 7 days and 

24 hours, respectively, before the incident. The first officer’s last line check occurred on April 25, 

2017, and his last recurrent ground training occurred on December 29, 2016. The first officer had 

no previous accident or incident history.

The first officer reported that he had twice attempted to upgrade to A320 captain. 

Air Canada records showed that the first officer passed his command line operational evaluation 

training on February 6 and 7, 2017, and that he did not pass his qualifying oriented evaluation 

training on March 1 and 16, 2017. According to the simulator instructors and check airmen who 

conducted the first officer’s upgrade attempts, the first officer had occasional difficulty 

maintaining situational awareness and did not perform in accordance with required 

Transport Canada standards.40 Air Canada’s director of safety and training stated that the first 

officer subsequently completed requalification training for the first officer position. The instructor 

who administered this training stated that the first officer performed “above average.” 

 40 A check airman who flew with the incident first officer (when he was attempting to upgrade to captain) stated 

that, during a flight, the incident first officer did not anticipate a potential flap overspeed event and respond to an 

increase in thrust that would have caused a flap overspeed. The instructor stated that he had to intervene before a flap 

overspeed occurred.
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72-Hour History

The first officer was off duty on July 4, 2017, and reported that he had a “proper” night’s

sleep then. On July 5, the first officer awoke about 0800 EDT and took a nap in the afternoon for 

90 minutes. He was a flight crewmember (the pilot flying) that night for a flight to SFO, which 

landed at 2305 (0205 EDT on July 6).41 The first officer went to sleep about 0400 EDT and awoke 

about 1000 EDT. He took a 1-hour nap in the afternoon and flew back to YYZ that night. The 

flight arrived on July 7 about 0030 EDT, and the first officer went to sleep about 0300 EDT. He 

awoke about 0900 EDT, took a 90-minute nap about 1300 EDT, and reported for duty at 1910 EDT 

(30 minutes before the scheduled report time). The first officer stated that both he and the captain 

began to feel “very tired” between 2330 and 0000 (0230 and 0300 EDT on July 8).

42 At the time 

of the incident, the first officer had been awake for more than 12 hours. Table 3 shows the first 

officer’s sleep schedule during the 72 hours before the incident. 

Table 3. First officer’s self-reported sleep schedule. 

Date Bedtime (EDT) Awakening time (EDT) Sleep opportunity

July 4 to 5 Unknown Unknown Unknown

July 5 to 6 0400 1000 6 hours plus 1-hour nap (7 hours)

July 6 to 7 0300 0900 6 hours plus 1.5-hour nap

(7.5 hours)

The first officer thought that he needed 8 hours of sleep each night to feel rested and 

considered himself to be a “pretty heavy sleeper.” He also considered himself to be a “normal day 

person” and stated that he typically felt tired about 2300 EDT. He normally took a nap in the 

afternoon for about 90 minutes on the days that he was scheduled for a nighttime flight. The first 

officer reported that he slept well during naps and felt rested afterward.

The first officer reported that he did not take any prescription or nonprescription medicine 

in the 72 hours before the incident that would have affected his performance. The first officer also 

reported that he did not use tobacco products or illicit drugs and that his last alcohol consumption 

before the incident was dinnertime on either July 3 or 4. He further reported no issues with his 

health and had no changes to his health, financial situation, or personal life within the 12 months 

before the incident that would have affected his performance on the day of the incident.

1.3 Airplane Information

The incident airplane, shown in figure 2, was owned by GE Capital Aviation Services, 

which leased the airplane to Air Canada. The airplane’s transport-category airworthiness 

certificate was dated January 17, 1992. The airplane was powered by two CFM56-5A1 engines

and had 2 flight crew seats, 1 jumpseat, 5 cabin crew seats, and 154 passenger seats. The airplane’s 

last inspection before the incident occurred on June 25, 2017, at which time the airplane had 

accumulated a total of 82,427 hours of flight time. 

 41 SFO lighting logs showed that runway 28L closed at 2323 on July 5. 

42 As indicated in section 1.1, the flight crewmembers also reported feeling tired just after they maneuvered the 

airplane through the thunderstorms. 
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Source: Air Canada. 

Figure 2. Incident airplane. 

1.4 Airport Information

SFO was located 8 miles southeast of San Francisco at an elevation of 13 ft msl. The airport 

was owned and operated by the city and county of San Francisco and was certificated under 

14 CFR Part 139. SFO had four runways (two sets of parallel runways) designated as 10L/28R,

10R/28L, 1R/19L, and 1L/19R, as shown in figure 3. Runway 10L/28R was 11,870 ft long and 

200 ft wide. Runway 10R/28L was 11,381 ft long and 200 ft wide. Runway 28R was equipped 

with a localizer that was aligned with the 284° runway heading. Taxiway C, which was to the right 

of runway 28R (as viewed from the approach end of the runway), was 12,330 ft long and 75 ft 

wide.
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Figure 3. SFO layout map. 

The SFO inspection log showed the runway, taxiway, signage, and lighting inspections 

surrounding the time of the incident. On July 7, 2017, runway 28R was inspected at 1550, 

runway 28L was inspected at 1609, and all taxiways were inspected at 2108. On July 8, the airport 

signage was inspected at 0211, and the airport lighting was inspected at 0339. No discrepancies

were noted for any of these inspections.

Title 14 CFR 139.311, “Marking, Signs, and Lighting,” stated that “each certificate holder 

must provide and maintain lighting systems for air carrier operations when the airport is open at 

night.” The regulation required runway and approach lighting that met specifications for takeoff 

and landing minimums. The regulation also required that taxiways have one of four lighting 

systems, one of which was centerline lights. 
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The airport light status (on/off) and intensity were controlled from the ATCT. Runway 28R 

was equipped with white runway edge lights, white centerline lights, white touchdown zone lights, 

and an approach lighting system with white centerline sequenced flashing lights (ALSF-2).

43

Runway 28R was also equipped with a four-light precision approach path indicator with a 

3° glidepath that was located on the left side of the runway. Taxiway C was equipped with green 

centerline lights that were spaced at 50-ft intervals (± 5 ft), blue taxiway edge lights located at the 

intersections with runway 28R to highlight the edge of the intersections, and flashing yellow 

in-pavement guard lights located where taxiway C intersected runway 1R/19L (which ran 

perpendicularly to runways 28L and 28R and taxiway C).

44 Figure 4 shows an illustration of the

lighting on runway 28R and taxiway C. On the night of the incident flight, the runway and taxiway 

centerline lights were set at step 1 (out of 5).

Figure 4. Illustration of SFO’s lighting configuration.

Note: The green runway threshold lights (for runway 28R) are also shown. 

Figure 4 also shows the ALSF-2 approach lighting system installed on runway 28R. The 

approach lighting system had a total of 24 white centerline bar lights that were spaced at 100-ft 

 43 (a) An approach lighting system is a ground reference aid for pilots when making an approach to a runway. 

(b) The runway centerline lights were white until the last 3,000 ft of the runway. From 3,000 to 1,000 ft, the color of 

the lights alternated between red and white. For the last 1,000 ft, all of the lights were red. (c) The runway edge lights 

transitioned from white to amber for the last 2,000 ft of the runway.

44 (a) During postincident interviews, the flight crewmembers recalled seeing specific color cues, including the 

green taxiway centerline lights, while on approach to SFO. (b) The taxiways at YYZ had green centerline lights that 

were spaced at 15-m (about 50-ft) intervals, retroreflective markers on the straight edges of the taxiways, and blue 

edge lights around turns and at intersections.
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intervals and faced the direction of approaching aircraft, and 15 of the white centerline bar lights 

extended into San Francisco Bay. Sequenced flashing lights (strobes) were positioned on the 

15 centerline bar lights that were farthest from the runway to create, when the sequenced flashing 

lights were turned on, the appearance of a rapidly moving light toward the runway.

45 During 

postincident interviews, the tower controller who handled the incident flight stated that, on the 

night of the incident, the approach lighting system was on, and the DAL521 captain stated that the 

sequenced flashing lights were not on.

The purpose of the construction project on runway 10R/28L at the time of the incident was 

to resurface the runway and replace existing light fixtures with improved lighting.

46 The project 

started in February 2017 and was expected to last about 10 months.

47 The work required the 

closure of the runway each night and during some weekends. At the time of the incident, 

28 portable light plants were located around the construction zone.48 A runway closure marker (a 

white flashing lighted “X”) was placed at the approach and departure ends of runway 28L when 

the runway was closed. The lighted “X” was 20.5 ft by 20.5 ft and flashed on for 2.5 seconds and 

then off for 2.5 seconds, which was consistent with Federal Aviation Administration (FAA) 

Advisory Circular (AC) 150/5345-55A, “Specification for L-893, Lighted Visual Aid to Indicate 

Temporary Runway Closure.”49 The flashing light associated with the “X” on runway 28L could 

be seen on an SFO security video that captured the incident. (See section 1.5.1 for information 

about the video).

One of the controllers at the SFO ATCT stated, during a postincident interview, that he had 

noticed an increase in pilot requests to adjust the lights for runway 28R due to the construction on 

runway 28L. According to the SFO acting air traffic manager, after the incident, controllers at the 

SFO ATCT were directed to (1) increase the intensity of the approach lights by one step if the 

adjacent arrival runway is closed and (2) when construction is ongoing, ask the pilots of the first 

arriving airplane after dark if the construction lighting is distracting.

 45 Controllers normally select a lighting setting based on the weather conditions. On the night of the incident, the 

weather was VMC, so the sequenced flashing (strobe) lights would not have been on (unless a pilot requested them). 

46 The replacement lighting included new runway-to-taxiway lead-on/lead-off lights, takeoff hold lights, and 

runway entrance lights.

47 The runway 10R/28L project was completed on December 18, 2017. 

48 Each light plant extended up to 30 ft and included four elliptical light fixtures that used 1,000-watt halide light 

bulbs.

49 The L-893 runway closure marker currently in use in the national airspace system was intended for short-term 

closures. This marker resulted from a research project conducted at the FAA Technical Center, the results of which 

were published in a January 1987 technical report. According to the report, the development of a lighted visual aid to 

denote closed runway surfaces included the following performance criteria: (1) the visual aid should be conspicuous 

when viewed from the air with and without other runway visual aids illuminated, (2) the visual aid should be visible 

from any point 0.5 mile from the runway threshold, (3) the visual aid should be suitable for night operations down to 

a visibility of 3 miles, and (4) the message presented by the visual aid should be intuitively understood (Marinelli 

1987). Various lighted visual aids were considered during this research project, and a lighted “X” was selected for 

evaluation. A similar lighted visual aid had been in operational use at SFO at that time, which “reinforced results” 

from the FAA Technical Center’s evaluation. The NTSB is not aware of any further FAA research for the L-893 

runway closure markers (after their implementation) except for assessing the use of light-emitting diode bulbs.
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1.4.1 Air Traffic Control Tower Staffing

The SFO ATCT operated 24 hours a day. At the time of the incident, the ATCT was staffed 

with two controllers who were assigned to the midnight shift (2230 to 0630). The controller 

handling the incident flight had been an FAA controller since December 2008 and had been 

working at the SFO ATCT since 2013. He was qualified and current on all positions at SFO and 

was designated as a controller-in-charge.50 The controller had also worked a daytime shift on 

July 7 from 0530 to 1330. The controller reported that he took a 45-minute nap in between the 

morning and midnight shifts and that he felt rested for his shifts.51 The controller also stated that 

he had “no problems” adjusting to the midnight shift.

The controller reported to the tower at 2230 on July 7 and initially worked the ground 

control position. (The other controller assigned to the midnight shift was initially working the local 

control position.) The front-line manager had briefed both controllers about the closure of 

runway 28L at 2300. About 2349, all ATCT positions and frequencies had been combined, and 

one controller worked the positions in the tower cab while the other controller took a recuperative 

break in the building.52 The controller who worked all positions configured his workstation to hear 

the SFO local control (tower) frequency and NCT interphone communications through his headset 

and the SFO ground control frequency over the workstation speaker.53

According to SFO ATCT personnel interviewed after the incident, the decision to combine 

positions to a single controller was made by the controllers on duty based on the anticipated 

traffic/workload and weather.54 The SFO acting air traffic manager indicated that SFO traffic 

generally begins to lessen after 0000 and tapers off significantly after 0100.

 50 Both controllers who were on duty during the midnight shift were qualified as controllers-in-charge. The 

controller who handled the incident flight was designated as the controller-in-charge for that shift. The SFO acting air 

traffic manager stated, during a postincident interview, that two controllers-in-charge were normally staffed for the 

midnight shift.

51 According to information that the controller provided during a postincident interview, he received 8 hours of 

sleep on the night of July 6 through 7.

52 FAA Order JO 7210.3Z, Facility Operation and Administration, stated that “breaks to recuperate are provided 

to enable employees to engage in activities necessary to rejuvenate themselves in order to effectively manage fatigue.” 

(FAA Order JO 7210.3Z, which was in effect at the time of the incident, was replaced by JO 7210.3AA on October 12, 

2017.) SFO ATCT personnel indicated that recuperative breaks during the midnight shift were longer than the breaks 

that were normally provided during other shifts.

53 The NCT and SFO ATCT letter of agreement, titled “Coordination and Control Procedures,” stated that “each 

facility must advise when going to a single person midnight operation,” but the SFO ATCT did not provide that 

notification to NCT on the night of the incident. The NTSB could not determine, from the available evidence, whether 

this situation was a recurring issue at the ATCT or occurred only on the night of the incident. NCT was not using 

single-person operations during the time surrounding the incident.

54 The two controllers assigned to the midnight shift evaluated the pending traffic on the flight schedule monitor, 

the depicted traffic in the national airspace system, and the expanded radar view of traffic within 40 miles of SFO and 

decided that it was safe to combine all positions. Also, NCT had provided the ATCT with the authority to automatically 

release IFR departures from SFO, which indicated a less complex traffic situation. The controller who took the 

recuperative break stated that there had been a “sharp decline” in the amount of traffic displayed before the ATCT 

positions were combined.
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The controller who handled the incident flight stated that traffic was “normal” before the 

incident and that he was not overly busy.

55 At the time that ACA759 called to confirm whether 

runway 28R was clear for landing, the controller was handling another air carrier’s tug operator, 

but he checked the radar monitor and the ASSC display and rescanned runway 28R before advising 

the flight crew that the runway was clear. The controller recalled that two other air carrier pilots 

had contacted him just before he heard the “where is that guy going?” transmission. The controller 

was unsure about who made this transmission, but he checked the ASSC display and saw that the 

ACA759 data symbol no longer appeared. The controller stated that he had never seen an airplane’s 

data symbol disappear when the airplane was on final approach. The controller also stated that he 

was not initially concerned that the ACA759 data symbol had disappeared from the ASSC display 

because he had observed the airplane from the tower cab window.

About that time, the controller heard the transmission indicating that an airplane was over 

the taxiway. The controller stated that he had never seen an airplane line up with taxiway C and 

that there was no indication that ACA759 was misaligned until he observed the airplane looking 

“extremely strange” on short final, which was about the time when he decided to instruct the flight 

crew to perform a go-around.56 The controller stated that, about 0125 on July 8, he entered a 

mandatory occurrence report into the SFO ATCT’s data analysis and reporting system; this report 

was required when an airplane goes around within 0.5 mile from a landing threshold. After the 

incident, the controller continued working all positions until 0300, at which time the other 

controller assigned to the midnight shift returned to the tower cab. 

The controller who handled the incident airplane reported that, while working 

single-person operations on the night of the incident, he applied line up and wait (LUAW) 

procedures for other traffic.57 FAA Order JO 7110.65W, Air Traffic Control, which prescribes 

ATC procedures, indicated that LUAW procedures should be used to position an airplane for an 

imminent departure when a takeoff clearance cannot immediately be issued because of traffic.58

Paragraph 10-3-8 of FAA Order JO 7210.3Z stated that, when applying LUAW procedures, the 

“local control position must not be consolidated/combined with any other non-local control 

position. For example, local control must not be consolidated/combined with the front-line 

manager/controller-in-charge (CIC) position, clearance delivery, flight data, ground control, cab 

coordinator, etc.” The order also stated that, during LUAW operations, “the front line 

manager/CIC position should not be combined with any other position.” 

During a postincident interview, the SFO acting air traffic manager stated that, if LUAW 

procedures were needed to efficiently move traffic, then traffic was “too busy to combine 

 55 The controller also stated that he would not combine positions unless he was comfortable and had some 

predictability about the tasks that he would need to perform. The controller further stated that, if the traffic had become 

too busy or complex, he would have asked the other on-duty controller to return to the tower cab to assist.

56 The distance and angle (parallax) of the tower cab relative to the approach end of runway 28R and taxiway C 

would have made it difficult for the controller to discern that the airplane was aligned with the taxiway instead of the 

runway. Parallax is the change in apparent position due to the viewing angle.

57 During a postincident interview, the controller stated, “when aircraft were on a 5-mile final and compressing 

[the distance between two aircraft was decreasing], it was hard to fit in a departure from runway 1, without using 

LUAW.”

58 FAA Order JO 7110.65W, which was in effect at the time of the incident, was replaced by JO 7110.65X on 

September 12, 2017.
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positions.” The SFO acting air traffic manager also stated that, after the incident, ATCT 

management issued guidance indicating that the ground control and local control positions could 

not be combined before 0015.59 In addition, the SFO acting air traffic manager stated that ATCT 

management had been reemphasizing the correct application of LUAW procedures. 

1.4.2 Air Traffic Control Tower Equipment

The SFO ATCT was equipped with an ASSC system, which was one of three types of 

airport surface detection equipment (ASDE) systems in the national airspace system. FAA Order 

JO 7110.65W described the use and purpose of ASDE as follows: 

Surveillance equipment specifically designed to detect aircraft, vehicular traffic, 

and other objects, on the surface of an airport, and to present the image on a tower 

display. Used to augment visual observation by tower personnel of aircraft and/or 

vehicular movements on runways and taxiways. 

Also, the order indicated that the ASSC system used surface movement radar, multilateration, and 

the Automatic Dependent Surveillance-Broadcast system.

60

According to FAA Order JO 7110.65W, the ASSC system included a safety logic system 

software enhancement that “predicts the path of aircraft landing and/or departing, and/or vehicular 

movements on runways.” The order stated that “visual and aural alarms are activated when the 

safety logic projects a potential collision.” Specifically, the system was designed to provide an 

alert for “an actual situation involving two real safety logic tracks (aircraft/aircraft, aircraft/vehicle, 

or aircraft/other tangible object) that safety logic has predicted will result in an imminent 

collision.” The order also stated that the system could generate false and nuisance alerts and could 

result in an “Invalid Non-Alert,” which involves “a situation in which the safety logic software did 

not issue an alert when an alert was required, based upon the design specifications.” 

According to the FAA, at the time of the incident, the ASSC system was available at SFO 

and Cleveland Hopkins International Airport, Cleveland, Ohio (FAA 2018a).

61 The ASSC display 

in the SFO ATCT presented aircraft and vehicle positions over a map of the airport’s runways, 

taxiways, and approach corridors. The ASSC display included a two-dimensional presentation of 

 59 (a) At the time of the incident, the SFO ATCT’s standard operating procedures described staffing requirements 

between 0630 and 2200 but did not provide such requirements between 2200 and 0630 the next day. (b) In June 2018, 

the NTSB asked the SFO ATCT when the 0015 time became effective and what factors were used to determine this 

time. The SFO ATCT operations manager responded that the 0015 time became effective on July 8, 2017 (the day 

after the incident) and that normal traffic patterns, runway closures, administrative duties, and fatigue guidance were 

considered in determining the 0015 time. 

60 According to the order, the other two ASDE systems were ASDE-3, a surface movement radar, and ASDE-X, 

which used an X-band surface movement radar, multilateration, and the Automatic Dependent Surveillance-Broadcast 

system. The three ASDE systems functioned similarly, but the ASSC had some capabilities that the other two ASDE 

systems did not have, including the ability to display extended runway centerlines and expand the capture box (block 

of airspace) area. 

61 According to the FAA, six additional airports were scheduled to receive the ASSC system during the next few 

years. 
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the runway centerlines, which extended out to about 2.5 nm. Figure 5 shows the ASSC display at 

2356:21 on the night of the incident.

Source: FAA.

Figure 5. ASSC display at SFO. 

Note: (a) The top of the figure shows the extended runway centerlines for runway 28R and 28L, and the bottom of the 

figure shows the airport movement areas. (b) The NTSB added labels to the figure to emphasize pertinent information.

The SFO ATCT controller who was taking a recuperative break at the time of the incident 

stated that the ASSC system assisted ground controllers in identifying airplanes and their locations 

and preventing runway incursions. He also stated that local controllers used the system as an “extra 

set of eyes” to assist with scanning and situational awareness. This controller also stated that the 

ASSC system provided airplane location information starting about the time that an airplane was 

on a 2-mile final approach. Another SFO ATCT controller stated that the ASSC system could be 

programmed to display runway and taxiway closures. 

In February 2018, the FAA conducted tests at Seattle-Tacoma International Airport (SEA),

Seattle, Washington, to determine if the ASDE-X system at the airport could detect and predict 

taxiway landings with only a negligible number of nuisance or false alarms.

62 NTSB staff observed

the tests and participated in the discussion of the test results. 

 62 On December 19, 2015, a Boeing 737 airplane operated by Alaska Airlines landed on a taxiway instead of the 

intended runway at SEA. The crew and passengers were not injured, and the airplane was not damaged. The incident 

occurred during daytime VMC. For more information about this incident, see NTSB incident number DCA16IA036.
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For the tests, the system was configured to apply the same parameters that are used to 

predict a landing on a closed runway.63 The tests included four different taxiway landing scenarios 

(one of which was similar to the circumstances of the SFO incident), and an FAA flight check 

airplane flew several approaches for each scenario. The tests showed that the ASDE-X system 

predicted the potential taxiway landing and provided an alarm when the airplane was within 

20 seconds or 3,000 ft of landing. The ASDE-X alarm occurred with enough time for ATC 

personnel to respond. No false alarms occurred during any of the approaches and taxiway landing 

scenarios, including those involving parallel taxiway B, which is located 407 ft to the left of 

runway 16L (centerline to centerline). According to information that the FAA provided to the 

NTSB on September 13, 2018, a software enhancement, the taxiway arrival prediction capability, 

was implemented at SEA in May 2018, and the FAA has a schedule to evaluate the remaining 

ASDE-X-equipped airports and implement the software enhancement, where feasible, by the end 

of fiscal year 2020.

1.5 Tests and Research

1.5.1 Airplane Performance Study

The NTSB conducted an airplane performance study for this incident to determine the 

lowest altitude over the taxiway that ACA759 reached before the initiation of the go-around and 

the estimated distance between ACA759 and the second airplane on taxiway C (PAL115, which 

was below ACA759 when it reached its lowest altitude). To conduct the study, the NTSB used 

FDR data; radar data from the airport surveillance radar-9 at Metropolitan Oakland International 

Airport, Oakland, California; and video from a security camera at an SFO terminal.64

The security video showed ACA759 on final approach to the airport, as shown in figure 6. 

The reflection of the airplane’s lights could be seen on the water in San Francisco Bay. Three of 

the four airplanes on taxiway C (UAL1, PAL115, and UAL863) are visible in the figure. 

 63 All of the ASDE systems could be configured to predict a potential landing on a closed runway and provide 

alerts if this hazard was detected.

64 The radar, which was about 10 nm from the incident location, updated data every 4.5 seconds.
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Source: SFO. 

Figure 6. ACA759 on final approach to SFO.

The security video also showed ACA759 passing over the airport seawall and then passing 

over UAL1 on taxiway C, as shown in figure 7. About this time, the PAL115 flight crew turned 

on that airplane’s landing lights, which illuminated the taxiway between PAL115 and UAL1 as 

well as the tail and side of the UAL1 airplane. In addition, the security video showed the fuselage 

of PAL115, which was illuminated by the ACA759 landing lights, and ACA759 descending to its 

lowest altitude as the airplane passed over PAL115. At that point, the attitude of the ACA759 

airplane changed from nose down to nose up, as shown in figure 8. Subsequent frames of the 

security video showed ACA759 gaining altitude over the taxiway and passing over UAL863 and 

UAL1118. (UAL863 is shown in figures 7 and 8, but UAL1118 is not shown in those figures). 
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Source for top image: SFO. 

Figure 7. ACA759 passing over UAL1 (top) and relative locations of airplanes (bottom).

Source for top image: SFO. 

Figure 8. ACA759 passing over PAL115 (top) and relative locations of airplanes (bottom).

Note: The PAL115 airplane, an A340, has a reported height of 55 ft. Although ACA759’s radio altimeter recorded the 

height above the ground of the bottom of the landing gear to be 60 ft, the security video showed more distance between 

the airplanes than the radio altimeter measurement. Specifically, the security video showed that the separation distance 

between the ACA759 fuselage and the PAL115 vertical stabilizer was 13.5 ft, as explained further in this report section.

The performance study considered the incident airplane’s pressure altitude and radio 

altitude, which the FDR recorded, when determining altitude points. Pressure altitude was used for 

altitudes that were higher than 2,000 ft. Radio altitude—the height of the airplane above the ground 
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directly below—was used for altitudes that were 2,000 ft and lower.

65 The adjusted radio altitude 

reflected the bottom of the airplane’s landing gear above the ground; the landing gear extended 

5 ft below the airplane’s fuselage.

The lowest adjusted radio altitude, which occurred when ACA759 passed over PAL115, 

was determined to be 60 ft, which was the height of the bottom of the landing gear above the 

ground. To confirm this altitude, the NTSB examined the image from the security camera video 

that showed ACA759 passing over PAL115 (figure 8). In that image, the vertical stabilizer of the 

PAL115 airplane (an A340) was well illuminated. The NTSB used known dimensions of an A340 

vertical stabilizer to scale the image, measured the closest point between the two airplanes, and 

determined that measurement to be 13.5 ft. Because the security camera image of the airplanes 

was relatively small and pixilated, this measurement was estimated to be between 10 and 20 ft to 

account for the inherent uncertainty. In addition, this measurement assumed that ACA759 was 

directly above PAL115; the lateral separation could not be determined from the image of ACA759 

passing over PAL115. The A340 airplane (including the vertical stabilizer) was reported to be 55 ft 

tall, so the altitude of the ACA759 fuselage as it passed over PAL115 would have been between 

65 and 75 ft, which was consistent with the 60-ft adjusted radio altitude plus the 5-ft distance 

between the bottom of the landing gear and the bottom of the fuselage.

The airplane performance study also determined the track of ACA759 while it approached 

SFO and was over taxiway C, as discussed in section 1.1 and shown in table 1. 

1.5.2 Enhanced Ground Proximity Warning System Simulation 

According to Honeywell, Air Canada installed Honeywell Mark V enhanced ground 

proximity warning systems (EGPWS) on the company’s fleet of A320 airplanes. According to 

Honeywell’s Mark V and Mark VII EGPWS Pilot’s Guide, the EGPWS incorporated several 

terrain alerting and display features. 

The EGPWS guide also described other features, including the runway awareness and 

advisory system (RAAS) option, which provides “alerts and advisories that increase crew 

situational awareness during operations on and around airports.” Another option was the 

SmartLanding system, which, according to Honeywell, “provides visual and aural annunciations 

that supplement flight crew awareness of...select RAAS advisories.” At the time of the incident, 

 65 According to Airbus, the radio altimeter should be set so that it reads 0 ft at airplane touchdown with an 

estimated average pitch of 6°. After ACA759’s final touchdown on runway 28R (after the second approach and 

landing), the radio altimeter recorded a value of -2 ft. For the airplane performance study, the radio altimeter 

measurement was adjusted +2 ft (the approximate height of the main landing gear wheels above the ground). No 

adjustments were made for the pitch of the airplane. In addition, the image of ACA759 and PAL115 when they were 

at their closest point was relatively small in the video frame, so the measurements were approximations. Thus, the 

altitudes derived in the study had uncertainty associated with them.
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the EGPWS installed in Air Canada’s A320-200 fleet, including the incident airplane, did not

include the RAAS or the SmartLanding system options.

66

The NTSB asked Honeywell to conduct a simulation to determine if an EGPWS with the 

SmartLanding system would have alerted the incident flight crew about the potential taxiway 

landing. The simulation was run using a Mark V EGPWS in Honeywell’s laboratory in Redmond, 

Washington. Honeywell set the taxiway landing alert threshold at a radio altitude of 250 ft, which 

was the default setting, and incorporated parameters from the incident airplane’s FDR.67 The aural 

taxiway landing alert, “Caution Taxiway, Caution Taxiway,” was designed to annunciate between 

a radio altitude of 250 and 150 ft. The simulation showed that the incident flight crew would have 

received the aural taxiway landing alert when the airplane was at a radio altitude of 235 ft and was 

2,600 ft (0.43 nm) from the airport seawall. According to the results of the airplane performance 

study, the incident airplane reached that altitude just before the tower controller confirmed that 

runway 28R was clear.

The NTSB notes that Honeywell’s systems are examples of available systems designed to 

augment a pilot’s positional awareness during in-flight and ground operations; Garmin also has 

such a system available, and Rockwell Collins has a system in development. The three Honeywell 

systems described in this section all provide the alert “approaching [runway number]” before 

landing.

1.6 Organizational Information 

1.6.1 Descent, Approach, and Arrival Information

Air Canada’s A319/A320/A321 Aircraft Operating Manual, volume 1, section 4, “Standard 

Operating Procedures,” provided flight crews with information on preparing for the descent to the 

destination airport. The manual stated that descent preparation should be completed before the top 

of the descent. The manual also stated that the pilot monitoring was to “set navaids as required” 

on the “RAD NAV [radio/navigation]” page (referenced with the MCDU) and “check idents 

on...PFDs (ILS).” The manual further stated that the pilot flying was to review all MCDU 

programming by the pilot monitoring, including entries on the radio/navigation page.

Air Canada’s A319/A320/A321 Aircraft Operating Manual, volume 2, section 22-30,

“Auto Flight – Flight Guidance,” stated that the open descent mode maintains a target speed/Mach 

number with the autopilot/flight director pitch mode while autothrust (if activated) maintains idle 

thrust (unless the flight crew maintains idle thrust manually). Volume 1, section 4 of the manual, 

“Standard Operating Procedures,” described a selected approach (also referred to as an open 

 66 (a) Honeywell’s Mark V and Mark VII EGPWS Pilot’s Guide indicated that RAAS required a GPS source. At 

the time of the incident, Air Canada operated 42 A320-200 airplanes, some of which were equipped with a GPS; the 

incident airplane was not equipped with a GPS. A June 2018 e-mail from Air Canada to the NTSB indicated that all 

of the airplanes in the company’s A320-200 fleet had been equipped with a GPS. (b) Honeywell also offered another 

optional feature, the SmartRunway system, which was designed to alert flight crews to an impending taxiway landing 

as well as an impending taxiway takeoff. 

67 The FDR did not record true track, true heading, and vertical speed parameters, which were necessary for the 

simulation, so Honeywell derived those parameters using the magnetic heading, magnetic variation, drift angle, and/or 

pressure altitude that the FDR recorded.
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approach) as “Autopilot or Flight Director systems directed by pilot selected commands” and a 

managed approach as “Autopilot or Flight Director systems directed by FMGS [flight management 

guidance system] capabilities.”68 The FMGS-generated information on the electronic flight 

instrument system included the flight plan, the airplane’s position and lateral deviation from the 

flight plan, the approach, and raw data from tuned navigational aids.

Air Canada’s Flight Operations Manual, section 8.9.10.1, “Arrival Preparation,” stated 

that, before briefing the arrival and approach, a flight crew should obtain the current ATIS, review 

applicable NOTAMs, and program the FMS/FMGS with the required data and cross-check the 

entries with the appropriate charts. Section 8.9.10.3, “Arrival and Approach Briefing,” provided 

flight crews with information on briefing the approach and arrival into an airport. The manual 

stated that the purpose of the arrival and approach briefings, which the pilot flying was required to 

perform for all approaches (including visual approaches), was “to enhance situational awareness 

and clarify expectations.” The manual also addressed the threat briefing, indicating the following: 

Beginning with the Pilot Monitoring (PM)...and ending with the Pilot Flying (PF), 

each crew member should identify any relevant threats that are anticipated during 

descent, arrival, approach, landing and taxi-in that pertain to their role, as well as 

strategies to mitigate them.

Air Canada’s Threat Briefing Reference Card indicated that a threat briefing was expected 

to be performed as part of the approach briefing. The card also indicated that the threat briefing 

was to be performed by both the pilot flying and the pilot monitoring. The card included examples 

of threats involving the airplane, operations, ATC, the runway, adverse weather, the operating 

environment, and the flight crew.

69 “NOTAMS” was listed under the “Operations” heading, 

“Lighting” was listed under the “Runway” heading, and “Alertness” was listed under the 

“Flight Crew” heading.

Air Canada’s A319/A320/A321 Aircraft Operating Manual, volume 1, section 4, “Standard 

Operating Procedures,” provided flight crews with guidance about crew coordination during the 

approach. The manual stated the following:

The PM must maintain a high level of vigilance in monitoring aircraft position, 

attitude and configuration and pay close attention to instrument indications. The PF 

must monitor position through both external references and by reference to NAV 

systems, including DME [distance measuring equipment] and NAV Display. Use 

automation functions to the greatest extent possible. Good crew communication is 

important.

Air Canada’s A319/A320/A321 Aircraft Operating Manual, volume 1, section 11,

“Approach,” provided flight crews with stabilized approach criteria for various approaches. For 

 68 A managed descent is also directed by the FMGS. Most of the Air Canada pilots who were interviewed after 

the incident stated that they would have flown the FMS Bridge visual approach to runway 28R as a managed descent 

due to the altitude restrictions and the associated increased workload. Also, the incident first officer stated that he flew 

a managed descent during the flight into SFO 2 nights before the incident.

69 The threat briefing card further indicated that the threats included on the card were not “an exhaustive list of 

all possible threats” and that the flight crew was responsible for briefing any additional threats that might be present. 
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visual approaches, the manual provided the following criteria: “lateral tracking as close as possible 

to the extended runway centerline or published inbound course” and “vertical tracking on 

approximately a 3 degree glide path and using visual approach slope indicators...if available.”70

The manual also stated that the pilot flying and the pilot monitoring should closely monitor flight 

parameters and that the pilot monitoring should call out any deviation that exceeded the established

parameters. Air Canada’s Flight Operations Manual, section 8.11.9.3, “Go-Around,” stated that a 

go-around should be initiated if “stable approach parameters cannot be met and maintained inside 

the appropriate gates” (1,000 and 500 ft above airport elevation).71

1.6.2 Crew Resource Management

Air Canada provided its pilots with a crew resource management (CRM) manual that 

included, among other subjects, communication, situational awareness, planning, 

decision-making, workload management, active monitoring, and threat and error management. A 

separate document, the company’s CRM competency guide, addressed each pilot’s responsibilities 

in the areas of situational awareness, decision-making and problem solving, workload 

management, professional management, and active monitoring and threat and error management 

procedures. In the area of situational awareness, the guide indicated that a captain was to 

“recognize and effectively respond to indications of reduced situational awareness from other crew 

members.” In the area of active monitoring and threat and error management procedures, the guide 

indicated that the pilot monitoring was to “communicate all errors, omissions, and differences in 

situational awareness and ambiguities to the PF assertively.” Also, in the area of active monitoring 

and threat and error management procedures, all pilots were to “detect deviations from the desired 

aircraft trajectory and take appropriate action.”

Air Canada provided CRM training during new hire, recurrent, and command upgrade 

training. The incident captain reported that the training was conducted in a classroom setting with 

mostly lectures and some scenarios. In 2016, Air Canada revised its CRM training to reflect a 

threat and error management model. This model focused on the following four levels (from top to 

bottom) of threat management: 

• Proactive—the flight crew briefs and mitigates threats before they are encountered.

• Reactive—an unexpected threat has occurred that the crew must recognize and 

respond to. If the crew manages the threat, then no error occurs.

• Errors and error management—the crew has mismanaged the threat, and a 

procedural, communication, or handling error has occurred. If the crew traps the 

error, safety margins will be maintained.

 70 Postincident interviews and airplane track data suggested that the flight crew used the precision approach path 

indicator located to the left of runway 28R for glidepath information. FDR data showed that, after the airplane passed 

F101D (at an altitude of about 1,100 ft), the airplane’s glidepath was between 2.1° and 3.2°.

71 As discussed in section 1.1, other criteria for initiating a go-around were “landing will not be accomplished 

within the touchdown zone” and “landing will not be accomplished on the runway centerline.”
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• Undesired aircraft state—a flight crew-induced aircraft state has occurred that 

clearly reduces safety margins and results in a safety-compromised situation.

The captain’s and the first officer’s CRM skills were highly rated by other pilots who had 

flown with them. Although a check airman expressed concern about the first officer’s situational 

awareness (as indicated in section 1.2.2), the check airman described the first officer’s overall 

CRM as “good.” 

1.6.3 Fatigue Information 

Air Canada’s Flight Operations Manual provided information regarding the development 

of fatigue and fatigue management. Section 4.12.3, “Circadian Basics,” stated that humans “have 

an internal circadian clock that regulates physiological and behavioural functions on a 24-hour 

basis” and that “the clock coordinates daily cycles of sleep/wake, performance, physiology, mood, 

and other functions.” The manual also discussed circadian disruption by stating that “the circadian 

clock cannot adjust immediately when a person suddenly changes schedule (e.g., by flying into a 

new time zone or changing to a new work/rest schedule).” The manual further stated that flying 

into a new time zone produces “a challenge to the circadian clock” because “it can take several 

days or weeks for the clock to get into step with the new local time.” In addition, the manual stated 

that, between 0300 and 0500 (body clock time zone), “physiological sleepiness peaks, and virtually 

all aspects of alertness and performance slow and can be reduced.”

Section 4.12.5, “Preventive Strategies,” stated that “naps can acutely improve alertness and 

performance, and even short naps can provide benefits.” The manual also stated that “a nap reduces 

the duration of continuous wakefulness before a work period, and can be particularly beneficial 

before a period of night work, when the challenge of working through the circadian low point is 

also a factor.” 

Section 4.12.6, “Operational Countermeasures,” discussed strategies for pilots to 

counteract fatigue while on duty. The section noted that such countermeasures, which included 

controlled rest (a planned cockpit rest period to improve subsequent performance and alertness) 

were “meant to temporarily enhance alertness and performance...so that operational safety and 

efficiency are maintained.” Regarding controlled rest, the manual advocated the use of “strategic 

naps” in appropriate circumstances and indicated that “napping is the only operational 

countermeasure that addresses one of the major physiological causes of fatigue – the need for sleep 

– and reverses it.”72

1.6.4 Event Reports

Air Canada’s Flight Operations Manual, section 12.2, “Definitions, Procedures, and 

Report,” stated the following: “Any aircraft accident, incident, emergency, or other safety related 

event which may require investigation, monitoring or tracking shall be reported to Dispatch as 

soon as possible. In addition, the flight crew should file an ASR [air safety report] when time 

 72 Air Canada officials stated, during postincident interviews, that the company’s controlled rest policy is 

generally used by overseas flight crewmembers who do not have a relief crewmember. Air Canada requests that 

crewmembers who use the controlled rest policy file a fatigue report.
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permits.”73 (ASRs are voluntary.) The section provided examples of reportable safety events, 

including unusual or abnormal aircraft handling; significant navigation errors or technical 

navigation problems; breach of air regulations, ATC irregularities, or a near miss; an unstable 

approach; a go-around; and any other hazard that poses a direct threat to flight safety. 

Chapter 3 of the manual, “Safety Management System,” section 2.5.1, stated that an ASR 

is “an electronic or paper medium through which employees are able to identify hazards, incidents, 

and accidents which impact the operational safety of Air Canada.” The section also stated that 

ASRs are “de-identified and accessible by all levels of management who are required to regularly 

review, provide feedback, and monitor the progress of analysis and investigations.” 

During postincident interviews, the first officer stated that he and the captain met about 

1100 on the morning after the incident to discuss the facts of the incident for the ASR, and the 

captain stated that he contacted company flight dispatch later that day to report the event.74 Air 

Canada records showed that the captain reported the event to dispatch about 1608 (1908 EDT) on 

July 8. The dispatcher who spoke with the captain stated that he reported that the airplane was 

lined up with the wrong runway and that a go-around ensued.75 The dispatcher also stated that the 

captain’s report sounded “innocuous” and that, because of the late notification (16 hours after the 

incident), he did not think that the event was serious.

The captain stated that he also spoke with the duty pilot to report that he had aligned the 

airplane with a taxiway and performed a go-around.76 The captain indicated that the duty pilot 

asked him whether the localizer was tuned, and the captain replied that it was not tuned for the 

first approach but was tuned for the second approach. According to Air Canada’s vice president of 

safety, after the flight crew notified the duty pilot of the incident, the senior director of line 

operations determined that the flight crew would be allowed to operate the flight from SFO to 

YYZ (using a different airplane than the incident airplane) and then “would be held out of service” 

after arriving at YYZ later that day. Air Canada’s director of corporate safety, investigations, and 

research stated that the incident airplane had flown about 40 hours before Air Canada senior 

officials became aware of the severity of the incident and realized that data from the airplane 

needed to be retrieved.77 Air Canada’s safety department was not consulted on the decision to keep 

 73 (a) Air Canada’s Flight Operations Manual, section 8.16, “Post Flight,” stated that flight crews should brief 

company dispatch after a flight about any “significant operational factors.” (b) At the time of the incident, Air Canada 

did not define “as soon as possible” regarding the pilot’s responsibility to report events to dispatch. In a May 2018 

revision to its Flight Operations Manual, Air Canada defined “as soon as possible” as “to accomplish promptly or as 

soon as time permits.” This and other postincident actions taken by Air Canada are discussed in appendix B. 

74 The captain stated that he did not report the incident to company dispatch shortly after it occurred because he 

was “very tired” and it was “very late.” 

75 The NTSB listened to a recording of the captain’s call to dispatch and confirmed that the captain indicated that 

he aligned the airplane with the “wrong runway.” 

76 Air Canada’s Flight Operations Manual, chapter 3, “Organizational Structure, Publications, and 

Documentation,” stated that the duty pilot was an Air Canada flight operations manager who was responsible “for all 

operational and administration decisions during times when other managers are not available.” The duty pilot acted 

on behalf of Air Canada flight operations senior management.

77 FDR data showed that the incident airplane departed SFO at 0747 (1047 EDT) on July 8 and arrived at Pierre 

Elliott Trudeau International Airport, Montreal, Canada, the same day at 1245 (1545 EDT). Because the airplane 

continued to fly after the incident occurred, CVR data from the incident flight were overwritten, and the FDR recorded 

more than 41 hours of data during eight flights after the incident flight.
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the incident airplane in service and have the flight crew continue with the planned flight to YYZ, 

even though the safety department was generally included on such decisions.78

During a postincident interview, the captain stated that the duty pilot asked him to file an 

ASR. The captain indicated that he had filed an ASR on July 8, but Air Canada’s director of 

corporate safety, investigations, and research stated that no safety report was on file when he 

learned about the event through an e-mail from the Transportation Safety Board of Canada (TSB) 

about 2200 EDT on July 9.79 (This director stated that the ASR had been “sitting in the system”

and was received on either July 10 or 11. The director further stated that company tablets were 

used to send ASRs and that the reports could only be transmitted if a tablet was connected to 

Wi-Fi.) 

The Air Canada A320 assistant chief pilot stated, during a postincident interview, that she 

and other Air Canada officials met with the incident flight crew on July 10. According to the A320 

assistant chief pilot, the flight crewmembers stated that they performed a go-around at an altitude 

of about 400 feet and that they did not realize that the airplane was aligned with a taxiway until 

“very late in the approach.” She also stated that the crewmembers were then told that ACA759 had 

overflown airplanes on a taxiway and that the crewmembers’ responses were “shock” and 

“surprise.”

In addition, the SFO acting air traffic manager reported that he and other ATCT personnel 

interviewed the incident captain at 1140 on July 8. During that conversation (which was not 

recorded), the acting air traffic manager notified the captain of the possible pilot deviation. 

According to FAA Order JO 7210.632, Air Traffic Organization Occurrence Reporting, this 

notification is provided when an “employee providing air traffic services determines that pilot 

actions affected the safety of operations.” The order also indicated that this notification was to be 

part of the air traffic mandatory occurrence report and that the flight crew should be notified “as 

soon as operationally practical.”80

1.6.5 Plan Continuation and Expectation Bias Training

On April 1, 2017, Air Canada implemented part of its training on plan continuation and 

expectation bias, which was presented to company pilots during annual recurrent training.81 This 

training comprised an 8-minute video, titled “Understanding Gut Feel.” The video explained that 

a gut feeling was “a sense of knowing things before we can consciously know them, or 

communicate them, or even explain them.” The video also explained that a gut feeling signaled 

that “something about this moment is different or strange, something has changed, and this 

 78 The NTSB could not determine, on the basis of the available evidence, why Air Canada’s safety department 

was not consulted on these decisions, but the company’s flight operations department had the authority to make such 

decisions without contacting the safety department. 

79 The NTSB learned about this incident from the FAA on July 9 at 1630 EDT (see appendix A) and notified the 

TSB about the incident at 1840 EDT the same day. 

80 The FAA order further indicated that this notification was “intended to provide the involved flight crew with 

an opportunity to make note of the occurrence and collect their thoughts for future coordination with Flight Standards 

regarding enforcement actions or operator training.” 

81 Air Canada developed this training after collaborating with a human factors contractor (who was hired a few 

years before the incident) to help improve the company’s performance. 
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something, yet to be discovered, poses a potential threat.” The video further explained that this 

“signaling usually lasts for only 3 to 4 seconds before we either check it out or talk ourselves out 

of what it is trying to tell us,” which “complicates our ability to translate the messages from the 

gut.” 

The video presented a basic strategy for listening to gut feelings when evaluating a 

situation, as expressed by the acronym “LIVE”: listen (to signals), investigate (what has changed 

or is different), validate (test and confirm a theory about what is different), and express 

(communicate the concern to others). The video added that, once a person begins listening to gut 

feelings, that person will become “much more aware and connected” to a working environment. 

The incident flight crewmembers had not received this training at the time of the incident 

because both had completed their most recent training (during the 2016/2017 training cycle) before 

the video became available (as part of the 2017/2018 training cycle). Air Canada indicated that the 

incident flight crewmembers would receive the training during their next annual recurrent training.

As part of its plan continuation and expectation bias training, Air Canada planned to 

introduce a 49-slide PowerPoint presentation during the 2018/2019 training cycle to (1) help 

company pilots understand why experienced professional pilots make errors and (2) examine 

mitigation strategies to overcome plan continuation and expectation bias. The NTSB’s review of 

the planned presentation found that it defined plan continuation bias as “unconscious cognitive 

bias to continue [an] original plan in spite of changing conditions” and expectation bias as “when 

someone expects one situation, she or he is less likely to notice cues indicating that the situation 

is not quite what it seems.” The slides presented two case studies, one in which a flight crew was 

affected by plan continuation bias, which led to a loss of situational awareness, and one in which 

a flight crew was affected by expectation bias, which led to crew confusion. The slides also 

presented countermeasures (which were company CRM competencies) to prevent plan 

continuation and expectation bias. 

1.6.6 Flight Information

Air Canada’s FMS Bridge visual approach to runway 28R, the NOTAM information that 

Air Canada provided in the ACA759 flight release to notify the flight crew about the runway 28L 

closure, and the display of the ATIS information transmitted to the flight crew about 2321 are 

shown in figures 9 through 11, respectively.82 The NTSB added a highlighted box with a dashed 

 82 The first officer stated that Air Canada had recently transitioned from paper flight releases to digital flight 

releases that were accessed on company tablets. The first officer also stated that he would circle or highlight important 

items on paper flight releases but that the company tablets in use at the time of the incident did not have that capability.

(The NTSB notes that the presentation of approach chart information was the same in the paper and electronic 

versions.) After the incident, Air Canada developed a means for its flight crews to highlight areas or make notes on 

digital flight releases.
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outline to each of these figures to emphasize information related to the circumstances of this 

incident.
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Source: Air Canada. 

Figure 9. Approach procedure (two pages).

Note: The NTSB added the highlighted box with a dashed outline (on the second page of the approach procedure) for 

emphasis. The approach chart is 8.5 inches long and 5.5 inches wide. 
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Source: Air Canada.

Figure 10. NOTAM showing runway 28L closure.

Note: (a) The NTSB added the highlighted box with a dashed outline for emphasis. (b) The information on this page of 

the flight release appeared under the gray highlighted heading “DESTINATION” on the previous page of the flight 

release. (c) The highlighted NOTAM was issued by the FAA; the third “NEW” NOTAM, which contains the same 

information as the FAA (domestic) NOTAM, was issued by the International Civil Aviation Organization. (d) Paper flight 

release information is 11 inches long and 8 inches wide.
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Figure 11. ATIS information Quebec.

Note: (a) The NTSB added the highlighted box with a dashed outline for emphasis. (b) This display of ATIS information, 

which was based on the raw text provided by Air Canada, represents what the flight crew would have seen on the 

ACARS screen. Nonpertinent items from the raw text, such as coding at the end of each line, have been deleted. The 

docket for this incident contains the raw ATIS information text. (c) ACARS information is printed on a paper roll that is 

4.25 inches wide. The length varies according to the information to be printed. 

1.7 Additional Information

1.7.1 Wrong Surface Landings Video

In August 2018, the FAA announced its new video highlighting wrong surface landings 

and provided pertinent data as part of the announcement (FAA 2018b). The FAA’s data showed 

that 85% of wrong surface landings involved general aviation aircraft (with the remainder 

involving commercial aircraft). The data also showed that parallel runways accounted for 75% of 

wrong surface landings. In addition, the video (dated July 25, 2018) indicated that 85% of wrong 

surface landings occurred at level 9 or lower ATCT facilities.83

1.7.2 Safety Alert for Operators

On August 18, 2017, the FAA issued Safety Alert for Operators (SAFO) 17010, “Incorrect 

Airport Surface Approaches and Landings,” to provide “some best practices for approaching and 

landing on the correct airport surface.” The best practices described in the SAFO included 

 83 Small ATCT facilities are classified as levels 4 through 6, and medium ATCT facilities are classified as levels 7

through 9. The SFO ATCT was considered to be a level 10 facility. 
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• performing a stabilized approach, which “is critical to pilots and flightcrews for 

maintaining situational awareness of the external environment”;

• using technology, including ILS and RNAV published approaches or FMS RNAV aids “to 

support pilot and flightcrew decisions”; 

• employing CRM, which is “imperative because it leverages the skills of all 

crew-members...and delineates job functions and the expectation of support”; 

• using available resources, which include reviewing airport lighting, reviewing and 

discussing NOTAMs, and monitoring ATIS information; and 

• being ready to go around, including understanding the reasons why a go-around might be 

warranted and, if necessary, taking that action “early, particularly during a time of 

confusion.” 

The SAFO indicated that the SFO incident highlighted the importance of these best 

practices. In the SAFO, the FAA strongly urged directors of operations, directors of safety, 

directors of training, and chief pilots to collaborate to 

• emphasize existing procedures to ensure approaches to and landings on the correct airport 

surface,

• provide information to flight crewmembers about recent incorrect surface landing events 

and the importance of proactively reducing that hazard, 

• ensure that all training refers to best practices that support approaches to and landings on 

the approved runway, and 

• emphasize the need for crew rest and vigilance when a work schedule “takes a crewmember 

outside of his or her normal day.” 

1.7.3 Canadian Fatigue Regulations 

Canada’s flight and duty time and rest requirements have been in effect since 1996. 

Transport Canada’s “Guidance Material Concerning Flight Time and Flight Duty Time 

Limitations and Rest Periods,” indicated the following about pilots on reserve duty: 
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When a flight crew member is on reserve, an air operator must provide the flight 

crew member with the opportunity to obtain at least 8 consecutive hours [of] sleep 

in any 24 hours by one of the 3 methods indicated in the standard. When that flight 

crew member is contacted and required to report for duty during the period of 

reserve duty, the flight crew member is no longer considered to be on reserve but 

on duty.... This means that at anytime during the reserve period, a flight crew 

member can be required to start a 14 hour duty period.... A flight crew member 

therefore must remain rested while on reserve such that they are able to cope with 

a full duty day if called.

Air Canada Pilots Association and Safer Skies, which comprises five unions in Canada, 

have been advocating for stricter rest requirements and flight time limitations to address pilot

fatigue, including fatigue in reserve duty pilots. In 2010, the Canadian Aviation Regulatory 

Advisory Council Working Group began an effort to update Canada’s regulations relating to 

fatigue (Canadian Aviation Regulations 700.16, “Flight Duty Time Limitations and Rest 

Periods.”) In 2014, Transport Canada released a draft of proposed new regulations and, in 2017, 

revised the draft regulations, but no changes to regulations relating to fatigue have been 

implemented. 
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2. Analysis

2.1 Introduction 

This incident occurred when ACA759 overflew four air carrier airplanes on a taxiway at a 

low altitude. ACA759 had been cleared to land on runway 28R at SFO, but the flight crew aligned 

the airplane with parallel taxiway C instead. The flight crew initiated a go-around, which avoided 

a collision between ACA759 and one or more of the airplanes on the taxiway. None of the 

crewmembers and passengers aboard the airplanes were injured, and none of the airplanes involved 

in this event were damaged. ACA759 was operated by Air Canada under IFR and the provisions 

of 14 CFR Part 129.

The following analysis discusses the incident sequence (section 2.2) and evaluates the 

following:

• reasons for the flight crew’s surface alignment error, including the roles of expectation bias 

and fatigue (section 2.3);

• the reporting of the incident (section 2.4);

• ATC issues, including frequency congestion and the technology available to SFO 

controllers at the time of the incident (section 2.5); and

• the effectiveness of runway closure markers currently in use in the national airspace system 

(section 2.6).

After completing a comprehensive review of the circumstances that led to this incident, the 

investigation established that the following factors did not contribute to the cause of the incident:

Flight crew qualifications. The flight crew was properly certificated and qualified in 

accordance with Canadian regulations, Air Canada requirements, and 14 CFR Part 129. 

Flight crew medical conditions. The flight crew held valid and current Canadian medical 

certificates. The captain and the first officer reported no medications, medical conditions, or sleep 

disorders during their required medical examinations and during postincident interviews.

Airplane mechanical conditions. The airplane was properly certificated, equipped, and 

maintained in accordance with Canadian regulations and 14 CFR Part 129. No evidence indicated 

any structural, engine, or system failures.

Airport lighting. Runway 28R (the intended landing runway for the flight) and parallel 

taxiway C at SFO met the requirements for lighting in 14 CFR Part 139. The runway 28R approach 

lights were on as the incident airplane approached SFO. Title 14 CFR 139.311 required taxiways 

to have one of four types of lighting systems, one of which was centerline lights, which were 

present and illuminated on taxiway C. The runway and taxiway centerline lights were set at step 1 

(out of 5), which was appropriate for the weather conditions on the night of the incident.
NTSB Aircraft Incident Report

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Thus, the NTSB concludes that none of the following were factors in this incident: 

(1) flight crew qualifications, which were in accordance with Canadian and US regulations; 

(2) flight crew medical conditions; (3) airplane mechanical conditions; and (4) airport lighting,

which met US regulations.

2.2 Incident Sequence

2.2.1 Notification of Runway 28L Status

SFO runway 28L was scheduled to close at 2300 on the night of the incident due to 

construction, and a NOTAM in the flight release for ACA759 provided information about the 

closure. The captain stated that he and the first officer discussed the runway 28L closure while at 

the departure gate but that they did not place much emphasis on this information because the 

captain thought that the flight would land before the runway would be closed.84 (The NTSB notes 

that the flight was originally scheduled to land 3 minutes after the runway 28L closure.) However, 

the airplane pushed back from the gate 30 minutes late due to the delayed arrival at YYZ of the 

airplane to be used for the flight and took off about 49 minutes later than the scheduled takeoff 

time. Even though the flight crewmembers knew, during their preflight preparations, about 

ACA759’s delayed departure, no evidence indicated that the crewmembers reconsidered the 

importance of the NOTAM information at that time or as the airplane approached SFO. For 

example, as part of the approach briefing, the flight crew was required to perform a threat briefing, 

but none of the threats that the pilots reportedly briefed related to the runway 28L closure.85

Air Canada’s standard operating procedures for preparing for an arrival into an airport 

indicated that the flight crew was, among other things, to obtain the current ATIS and review 

applicable NOTAMs. ACARS data showed that the flight crew requested ATIS information, and 

the ACARS message displaying ATIS information Quebec was sent to the airplane about 2321, 

which was several minutes before the airplane began its descent from cruise altitude; at that time, 

the crew’s workload would likely have been lighter compared with later phases of flight. The ATIS 

information included a NOTAM indicating that runway 28L was closed, but neither flight 

crewmember recalled seeing this information. Section 2.3.2 discusses the effect of the runway 28L 

closure on the flight crew’s ability to identify the intended landing surface.

2.2.2 Preparations for the Descent

Air Canada standard operating procedures stated that descent preparation should be 

completed before the top of the descent and listed the tasks that needed to be completed. The pilot 

monitoring (in this case, the first officer) was to use the MCDU to reference the radio/navigation 

page and set navigational aids into the FMC and then check that the ILS identifier shown on the 

 84 The captain provided this account during his second postincident interview with the NTSB. This information 

differed from the account that he provided, and the account that the first officer provided, during their first postincident 

interviews with the NTSB (see section 1.1). 

85 As previously stated, Air Canada’s Threat Briefing Reference Card indicated that NOTAM information was 

one of the threats expected to be included in a threat briefing. 
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PFDs was correct.

86 The pilot flying (in this case, the captain) was to review the approach 

programming in the MCDU and complete an approach briefing, which included verifying that the 

primary approach aid (ILS) identifier and frequency were properly set.

ATIS information Quebec indicated that the Quiet Bridge visual approach was in use and 

that arriving airplanes would be landing on runway 28R. The flight crew used Air Canada’s FMS 

Bridge visual approach procedure, which was based on the Quiet Bridge visual approach 

procedure, for the approach to runway 28R. Air Canada’s FMS Bridge visual approach chart 

consisted of two pages. The first page showed the approach procedure and included the ILS 

frequency for runway 28R in the plan view. The second page of the approach chart was in text 

format and indicated that Airbus A319/A320/A321 pilots should tune the ILS for runway 28R, 

which would provide flight crews with backup lateral guidance (via the localizer aligned with the 

runway heading) during the approach. This lateral guidance would supplement the visual approach 

procedures.

The first officer stated that, when he set up the approach in the FMC, he missed the step in 

the procedure to manually tune the ILS frequency, and FDR data showed that no ILS frequency 

had been entered for the approach. According to Air Canada personnel, the FMS Bridge visual 

approach was the only approach in the company’s Airbus A320 database that required manual 

tuning of an ILS frequency, which might have contributed to the first officer’s failure to input the 

frequency (as discussed below). However, the first officer’s error should have been caught by the 

captain as part of his verification of the approach setup during the approach briefing. If cockpit 

voice recorder (CVR) information had been available for this incident (as discussed further in 

section 2.4), the NTSB might have been better able to determine whether distraction, workload, 

and/or other factors contributed to the first officer’s failure to manually tune the ILS frequency 

and the captain’s failure to verify that the ILS frequency was tuned. The NTSB concludes that the 

first officer did not comply with Air Canada’s procedures to tune the ILS frequency for the visual 

approach, and the captain did not comply with company procedures to verify the ILS frequency 

and identifier for the approach, so the crewmembers could not take advantage of the ILS’s lateral 

guidance capability to help ensure proper surface alignment. 

The flight crew of DAL521, which preceded the incident airplane to SFO, was also flying 

the FMS Bridge visual approach to runway 28R. The DAL521 airplane landed on runway 28R 

without incident (despite confusion regarding the identification of the runway surface, as discussed 

in section 1.1.1) because the flight crew used LNAV guidance to align with the runway. The 

DAL521 captain confirmed that the airplane was aligned with runway 28R as he visually acquired 

the painted “28R” on the runway surface when the airplane was at an altitude of about 300 ft. The 

DAL521 captain stated, during a postincident interview, that the runway 28R and taxiway C 

surfaces could have been confused if the approach was not backed up with lateral guidance. 

The incident captain’s failure to recognize that the ILS frequency had not been manually 

tuned suggests insufficient preparation for the approach.87 The first officer might have missed the 

 86 One of the incident flight crewmembers would have had to select the “LS” buttons on the glareshield for ILS 

information to appear on the PFDs. 

87 The captain’s request for the first officer to set the runway heading, as discussed in section 2.2.3, also suggests 

insufficient preparation for the approach.
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step to manually tune the ILS frequency because Air Canada flight crews were not required to take 

this action for any approach other than the FMS Bridge visual approach, which provided an 

opportunity for an omission error (flight crew inaction). It is also possible that the first officer 

missed the information on Air Canada’s FMS Bridge visual approach chart about manually tuning 

the ILS frequency because of the presentation and position of that information. Specifically, the 

instruction was embedded in the middle of a paragraph on the second (and last) page of the 

approach chart, as shown in figure 9, which was not optimal for capturing pilot attention because 

the action item could be overlooked. The instruction to manually tune the ILS frequency for the 

FMS Bridge visual approach could have been emphasized, for example, as part of a bulleted list,

which Air Canada used in other company procedures to draw pilots’ attention to relevant 

information.

The NTSB concludes that the flight crew’s failure to manually tune the ILS frequency for 

the approach occurred because (1) the FMS Bridge visual approach was the only approach in 

Air Canada’s Airbus A320 database that required manual tuning of a navigation frequency, so the 

manual tuning of the ILS frequency was not a usual procedure for the crew, and (2) the instruction 

on the approach chart to manually tune the ILS frequency was not conspicuous during the crew’s 

review of the chart. Although the incident flight was operating under 14 CFR Part 129, the 

approach chart that the flight crew used was originally developed by an air carrier operating under 

14 CFR Part 121. Therefore, the NTSB recommends that the FAA work with air carriers 

conducting operations under 14 CFR Part 121 to (1) assess all charted visual approaches with a 

required backup frequency to determine the FMS autotuning capability within an air carrier’s fleet, 

(2) identify those approaches that require an unusual or abnormal manual frequency input, and 

(3) either develop an autotune solution or ensure that the manual tune entry has sufficient salience 

on approach charts. The NTSB notes that, after the incident, Air Canada revised its procedures so 

that the FMS Bridge approach to runway 28R would be flown as an instrument approach. (More 

information about Air Canada’s postincident actions can be found in appendix B.)

The NTSB notes that the FAA, as part of its work with the Commercial Aviation Safety 

Team (CAST), would be in an ideal position to act on Safety Recommendation A-18-23 through 

the CAST safety enhancement process because of the team’s shared interest in mitigating 

commercial aviation safety issues.88 Also, according to the FAA, CAST is moving toward “a 

proactive approach that focuses on detecting risk and implementing mitigation strategies before 

accidents or serious incidents occur” (FAA 2017).

2.2.3 Initial Approach

Air Canada’s procedures allowed pilots to decide whether to descend using the managed 

or open descent autopilot mode. The first officer reported that the approach was conducted using 

the open descent mode. With the open descent mode, pitch control maintains the target speed/Mach 

number, and autothrust maintains idle thrust. The captain reported that he initially flew the 

approach using the selected descent mode, which, according to Air Canada, was synonymous with 

the open descent mode. However, the captain also reported that he subsequently flew the approach 

using the managed descent mode, which guides an airplane to the deceleration point along the 

 88 In addition, the FAA has a broader oversight role of ensuring that operational risks are appropriately evaluated 

under air carriers’ safety management systems (14 CFR Part 5, “Safety Management Systems”).
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flightpath that was computed by the FMGS and, unlike the open descent mode, considers speed 

and altitude constraints.

The NTSB was unable to determine whether the approach was flown using the open or 

managed descent mode because of the differing statements from the captain and the first officer

and the lack of FDR parameters to show flight mode annunciator indications. However, the first 

officer perceived that the descent was being flown using the open descent mode, which increased 

his workload during a critical phase of flight because he had to ensure, among other things, that 

altitude constraints were met. The first officer stated that he thought that it was unusual to use the 

open descent mode, but he did not notify the captain about his concern because the procedure was 

allowed (until reaching the final waypoint on the approach, F101D). This and other breakdowns 

in CRM during the incident flight are discussed in section 2.2.5.89

The captain flew the FMS Bridge visual approach to runway 28R with the autopilot 

engaged until just before F101D. After the airplane reached F101D and the autopilot was 

disconnected, the first officer began setting the altitude and heading for a missed approach, which

diverted his attention from monitoring the approach as the captain aligned the airplane with 

taxiway C.90 The NTSB recognizes that the first officer set the missed approach altitude and 

heading at an appropriate time (given his perception that the airplane was being flown in the open 

descent mode). However, his attention was further diverted from monitoring the approach when 

the captain requested that the first officer set the runway heading. The first officer stated that he 

had difficulty locating the runway heading information on the approach chart and had to find it on 

another chart, which extended the first officer’s heads-down time after the airplane passed F101D. 

If the first officer had been monitoring the approach at this point, he might have realized, 

among other things, that the ILS frequency and identifier and the runway 28R extended centerline

were not depicted on his PFD.91 The NTSB concludes that the first officer’s focus on tasks inside 

the cockpit after the airplane passed the final waypoint reduced his opportunity to effectively 

monitor the approach and recognize that the airplane was not aligned with the intended landing 

runway.

2.2.4 Final Approach Segment and Go-Around

The airplane passed F101D at an altitude of about 1,100 ft. Shortly afterward, the captain 

noticed lights going across what he perceived to be the runway surface. According to the first 

officer, between that time and the time that the airplane descended to an altitude of 600 ft, the 

 89 Other breakdowns in CRM indicated an apparent lack of preparation for the approach, including both flight 

crewmembers’ (1) ineffective review of the runway 28L closure NOTAM before the flight and when ATIS 

information Quebec was received and (2) lack of discussion about the runway 28L closure during the approach 

briefing.

90 Because the first officer perceived that the approach was being flown using the open descent mode, he would 

not have set the missed approach altitude until the airplane reached its minimum altitude for the descent (1,200 ft msl) 

or the captain was no longer using the autopilot and flight director for guidance.

91 Air Canada’s stabilized approach criteria for a visual approach included lateral tracking as close as possible to 

the extended runway centerline or the published inbound course. However, the flight crew could not have verified that 

the airplane was tracking close to the extended runway 28R centerline given that the extended centerline information 

would not have been electronically depicted (because the ILS/localizer frequency had not been tuned).
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captain requested that the first officer contact the tower controller to verify that the runway was 

clear. According to the ATC voice recording and the NTSB’s airplane performance study, when 

the flight crew transmitted, “we see some lights on the runway there, across the runway. Can you

confirm we’re cleared to land?” the airplane was passing through an altitude of 300 ft. 

The controller had scanned the runway just before receiving the flight crew’s transmission. 

While receiving the transmission, the controller scanned the ASSC and radar displays to check for 

conflicts and scanned runway 28R again. The controller confirmed that the airplane was cleared 

to land and stated that no other airplanes were on the runway. At that point, the airplane was 

passing through an altitude of 200 ft. 

The airplane performance study for this incident showed that ACA759 continued the 

approach and flew over the first airplane on taxiway C (UAL1) at an altitude of 100 ft and that the 

flight crew initiated a go-around when ACA759 was at an altitude of 89 ft.92 The airplane 

performance study also showed that ACA759 flew over the second airplane on taxiway C 

(PAL115) at an altitude of 60 ft before the airplane began climbing, which resulted in only 10 to 

20 ft of vertical separation between the ACA759 and PAL115 airplanes. The NTSB concludes that 

the flight crew-initiated, low-altitude go-around over the taxiway prevented a collision between 

the Air Canada airplane and one or more airplanes on the taxiway. Because of the lack of CVR 

data for the incident flight, the NTSB could not determine what information the pilots discussed, 

if anything, before and during the go-around. Nevertheless, the NTSB was able to determine the 

cues that likely led to the flight crew’s recognition of its alignment error and the crew’s initiation 

of the go-around maneuver, as discussed in section 2.3.2.2.

The controller recalled that, when ACA759 was about 1/10 mile on short final, the airplane 

looked “extremely strange” regarding its location relative to runway 28R, taxiway C, and the 

airplanes along the taxiway. When the UAL1 captain stated, over the tower frequency, “where is 

that guy going?” at 2355:59, the controller expressed confusion regarding who had made the 

transmission.93 (The UAL1 captain did not identify himself during the transmission.) At that point, 

the controller, who had just checked runway 28R twice, was likely trying to process what he was 

seeing and hearing. The controller stated, during a postincident interview, that the transmission 

seemed “out of context.” 

The controller had no reason to think that ACA759 was lined up with taxiway C before he 

observed the airplane looking “extremely strange.” The ACA759 flight crew had reported that the 

airplane was on approach to runway 28R, and the ASSC display had previously predicted that the 

airplane would be landing on runway 28R. Also, the controller had not previously seen an airplane 

align with taxiway C. Further, the distance and angle (parallax) of the tower cab relative to the 

approach end of runway 28R and taxiway C would have made it difficult for the controller to 

visually recognize that ACA759 was aligned with the taxiway instead of the runway, especially at 

night and with the lights from the construction on runway 28L and airport vehicle movements. 

 92 As previously stated, all altitudes in this report are agl (unless otherwise indicated).

93 The ATC voice recording indicated that, 2 seconds after the UAL1 captain stated, “where is that guy going?” 

and 2 seconds before he stated, “he’s on the taxiway,” the controller stated to himself, “who is...talk?” 
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When the UAL1 captain stated, 4 seconds after his first transmission, “he’s on the 

taxiway,” the controller might have realized what had happened with ACA759. Because the flight 

crew had already begun the go-around maneuver (at 2356:05), the airplane was climbing at the

time of the controller’s go-around instruction (2356:09). The controller subsequently told the 

flight crew that the airplane appeared to have been lined up with taxiway C. The NTSB concludes 

that the controller responded appropriately once he became aware of the potential conflict. A factor 

that precluded the controller from determining sooner that a potential conflict existed was the 

ASSC system’s lack of capability to detect a taxiway landing and provide an alert, as discussed 

further in section 2.5.2.

2.2.5 Crew Resource Management Breakdown

Air Canada’s CRM manual for pilots and the company’s CRM competency guide 

addressed, among other subjects, situational awareness, workload management, active monitoring, 

and threat and error management. Several crew actions/inactions during the incident flight

demonstrated breakdowns in CRM, many of which were manifested as noncompliance with 

Air Canada’s standard operating procedures. These crew actions/inactions included 

• the flight crew’s ineffective review of NOTAMs in the flight release; 

• the flight crew’s failure to identify the runway 28L closure information within the ATIS 

information;

• the flight crew’s failure to conduct a complete approach briefing;

• the first officer’s failure to manually tune the ILS frequency and the captain’s failure to 

verify the tuning of the ILS frequency; 

• the first officer’s failure to express concern about the perceived use of the open descent 

mode; and

• the captain’s request, at the final waypoint (F101D), for the first officer to set the runway 

heading, which took the first officer by surprise and prolonged his heads-down time while 

the airplane was aligned with the taxiway.

The captain’s and the first officer’s CRM skills were highly rated by other pilots who had 

flown with them. Also, a review of Air Canada’s CRM training program indicated that the 

crewmembers received comprehensive CRM training. Thus, although errors indicating 

breakdowns in CRM occurred during the incident flight, those errors did not appear to be consistent 

with both crewmembers’ performance during other flights (except for a check airman’s report of 

the first officer’s performance during a flight) and the CRM training that the crewmembers 

received.

94 Possible explanations for the breakdowns in CRM during the incident flight include 

 94 A check airman who had flown with the first officer when he was attempting to upgrade to captain expressed 

concern about the first officer’s situational awareness, as stated in section 1.2.2.
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fatigue (discussed in section 2.3.3) and the high workload associated with the approach, but the 

NTSB could not identify the source of the breakdowns due to the lack of CVR information.

Air Canada’s CRM procedures were designed to reflect a threat and error management 

model. According to the top level of the model, flight crews were expected to proactively brief 

and mitigate threats before they are encountered. Company procedures required crews to brief 

potential threats during the approach briefing. Because both flight crewmembers could not recall 

the runway 28L closure NOTAM in the flight release and did not assimilate the runway 28L 

closure information included in the ATIS information, they did not identify the runway 28L closure 

as a potential threat associated with the approach. (If the flight crew had recalled the runway 28L 

closure information and briefed it as a threat, that action should have made the information more 

readily accessible for future recall.)

According to the next level of the model, flight crews were expected to respond when an 

unexpected threat has occurred and manage the threat so that no error occurs. When the captain 

aligned the airplane with taxiway C, he did not have any lateral guidance to indicate that the 

airplane was off course because of the first officer’s failure to tune the ILS frequency and the

captain’s failure to verify that the approach was properly set up. Also, the first officer, as the 

monitoring pilot, was required to communicate all errors and situational awareness concerns to the 

captain. However, the first officer was heads down when the captain aligned the airplane with the 

taxiway because of the time that it took the first officer to locate the runway heading information 

(in response to the captain’s instruction to set the runway heading) and the time needed for the first 

officer to set the missed approach altitude and runway heading. As a result, neither crewmember 

realized, once the airplane passed the final waypoint, that the airplane was not aligned with the 

intended landing runway. 

The threat and error management model further indicated that, if the flight crew 

mismanaged the threat, then a procedural, communication, or handling error could occur. If such 

an error occurs and the crew traps the error, then safety margins will be maintained. Even though 

the tower controller confirmed that runway 28R was clear, the flight crew recognized that 

something was not right with the approach about the time that the airplane passed over the seawall. 

According to the captain, the first officer called for a go-around at the same time as the captain 

initiated the go-around maneuver, thereby preventing a collision on the taxiway. 

Even though the flight crew performed a go-around at that point, safety margins were 

severely reduced given ACA759’s proximity to the ground (below 100 ft) before the airplane 

began climbing and the minimal distance between ACA759 and the airplanes on taxiway C. Thus, 

a flight crew-induced aircraft state that compromised safety—the bottom level of the threat and 

error management model——resulted from ineffective threat and error management. The NTSB 

concludes that errors that the flight crewmembers made, including their false assumption that 

runway 28L was open, inadequate preparations for the approach, and delayed recognition that the 

airplane was not lined up with runway 28R, reflected breakdowns in CRM and led to minimal 

safety margins as the airplane overflew taxiway C.
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2.3 Reasons for Flight Crew’s Misalignment With Taxiway C

The flight crewmembers had recent experience flying into SFO at night: the captain 

reported that he had flown into SFO one or two times during the previous 4 months, and the first 

officer was the pilot flying on a flight to SFO 2 nights before the incident. The flight crewmembers’ 

training records indicated no issues with identifying airport surfaces, flying stabilized approaches, 

and flying visual approaches. The incident occurred in night VMC, and no evidence indicated any 

obstructions or glare in the cockpit that would have affected the flight crew’s view outside of the 

cockpit windows. However, the flight crewmembers were unable to identify the runway 28R 

surface (despite the presence of approach and runway lighting) and instead aligned the airplane 

with parallel taxiway C. Also, neither crewmember recognized that the airplane was not aligned 

with the intended landing runway until the airplane was over the airport surface, at which time the 

flight crew initiated a low-altitude go-around. Sections 2.3.1 through 2.3.3 discuss reasons for the 

flight crew’s alignment error and the factors that led to the eventual recognition of this error, and 

section 2.3.4 discusses the mitigation of such errors.

2.3.1 Flight Crew Awareness of Runway Closure

The flight crew had opportunities before the approach to learn about the runway 28L 

closure. The first opportunity occurred before the flight when the crewmembers received the flight 

release. Both crewmembers stated that they reviewed NOTAMs in the flight release. However, the 

first officer stated that he could not recall reviewing the specific NOTAM that addressed the 

runway 28L closure. Also, even though the captain stated that he saw the runway closure 

information, his actions in misaligning the airplane demonstrated that he did not recall that 

information when it was needed, and he thought that runway 28R was runway 28L. The second 

opportunity occurred in flight during the crewmembers’ preparations for the approach to 

runway 28R. Both crewmembers recalled reviewing ATIS information Quebec, which they 

received via an ACARS message in the cockpit, but neither crewmember recalled reviewing the 

specific NOTAM in the ATIS information that described the runway 28L closure.

Because the flight crewmembers either did not review or could not recall the information 

about the runway 28L closure, they expected to see two parallel runways while on approach to 

SFO and further expected that they would need to fly the approach to the right-side surface.95 The 

flight crew’s recent experience flying into SFO would have reinforced these expectations. For 

example, when the first officer flew into SFO 2 nights before the incident, the airplane used for 

that flight landed on runway 28R at 2305, which was about 18 minutes before runway 28L was 

closed. Also, the captain stated that he had never seen runway 28L “dark” and that none of his 

previous landings at SFO occurred when a runway was closed. 

A runway closure marker with a flashing white “X” was placed at the threshold of 

runway 28L to indicate the runway closure. However, the flashing “X” would not have been in the 

flight crew’s direct field of view because the “X” was oriented toward the runway 28L final 

 95 Industry analysis of traffic patterns at SFO showed that airplanes landing on runway 28R tended to stay more 

to the right of course when runway 28L was open than when it was closed.
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approach corridor and the airplane was not aligned with runway 28L.96 Also, the flash rate might 

have been too slow to capture the crew’s attention.

97 (The conspicuity of the “X” to flight crews 

on final approach is further discussed in section 2.6.) The NTSB concludes that the flight 

crewmembers’ lack of awareness about the runway 28L closure and the crewmembers’ previous 

experience seeing two parallel runways at SFO led to their expectation to identify two runway 

surfaces during the approach and resulted in their incorrect identification of taxiway C instead of 

runway 28R as the intended landing runway.

The NTSB considered the presentation and priority of the runway 28L closure information 

compared with other information that the flight crew received. The flight release package was 

27 pages long and consisted of, among other items, route, weather, and NOTAM information. The 

NOTAM indicating the runway 28L closure (“RWY 10R/28L CLSD”) appeared on page 8 of the 

package, which was also the second page of NOTAM information, under the gray highlighted 

heading “DESTINATION” (which appeared on the previous page). Features of the NOTAM text 

emphasized the closure information, such as the use of bold font for the words “RWY” and 

“CLSD” and a “**NEW**” designation in red font with asterisks before the NOTAM text, as 

shown in figure 10.

98 However, this level of emphasis was not effective in prompting the flight 

crewmembers to review and/or retain this information, especially given the NOTAM’s location 

(toward the middle of the release), which was not optimal for information recall. A phenomenon 

known as “serial position effect” describes the tendency to recall the first and last items in a series 

better than the middle items (Colman 2006).

The ACARS message providing ATIS information Quebec, as displayed in the cockpit, 

was 14 continuous lines with all text capitalized in the same font. As shown in figure 11, the 

NOTAM indicating the runway 28L closure appeared at the end of line 8 and the beginning of 

line 9. The uniform presentation of the ATIS information could have contributed to the flight 

crew’s oversight of the runway closure information. The flight crew’s receipt of ATIS information 

Quebec via ACARS was consistent with Air Canada’s procedure to obtain ATIS information using 

either ACARS or VHF communications. Thus, effective presentation of information is important 

for flight crewmembers who obtain ATIS and other information via ACARS. The capability exists 

to make important information more conspicuous in an ACARS message by, for example, inserting 

line breaks within the text to group related information.

The NTSB concludes that, although the NOTAM about the runway 28L closure appeared 

in the flight release and the ACARS message that were provided to the flight crew, the presentation 

of the information did not effectively convey the importance of the runway closure information 

and promote flight crew review and retention. Multiple events in the National Aeronautics and 

Space Administration’s aviation safety reporting system (ASRS) database showed that this issue 

 96 The size of the “X,” 20.5 ft by 20.5 ft, would have appeared small along the 200-ft width of runway 28L. 

97 The “X” flashed on for 2.5 seconds and off for 2.5 seconds, equating to a frequency of 0.2 Hz. Although a 

0.2-Hz flash at the threshold of runway 28L might be effective at preventing the use of the runway when closed, the 

frequency might have been too low to have captured the attention of the ACA759 flight crewmembers unless they had 

explicitly focused their attention on the approach end of runway 28L.

98 Although the red text would have been visible during the crewmembers’ review of the flight release before 

departure, the low ambient lighting conditions in the cockpit would likely have made the red text less conspicuous.
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has affected other flight crews, indicating that all air carriers could benefit from improved 

information display in flight releases and ACARS messages.99

The way information is presented can significantly affect how information is reviewed and 

retained. Specifically, when pilots review information, their scan and retention of that information 

is influenced by the pilots’ perceived relevance of the information to a task. Thus, it is possible for 

a pilot to miss more relevant information when it is presented with information that is less relevant. 

Although human limitations (such as fatigue and time pressure/workload) may affect the review 

of information, these limitations can be overcome with effective information presentation. For 

example, items in the middle of a list can be better retained if the information is presented with 

“intensity” because a sharp, clear, or salient presentation has a better chance of being recalled 

compared with less visually stimulating information (FAA 2008). Therefore, the NTSB 

recommends that the FAA (1) establish a group of human factors experts to review existing 

methods for presenting flight operations information to pilots, including flight releases and general 

aviation flight planning services (preflight) and ACARS messages and other in-flight information; 

(2) create and publish guidance on best practices to organize, prioritize, and present this 

information in a manner that optimizes pilot review and retention of relevant information; and 

(3) work with air carriers and service providers to implement solutions that are aligned with the 

guidance. The NTSB notes that one way to ensure that air carriers effectively present and prioritize 

relevant information in flight releases and ACARS messages would be to develop an industry 

standard. 

2.3.2 Role of Expectation Bias

2.3.2.1 Initial Taxiway Misalignment

Because the flight crewmembers were not aware of the runway 28L closure, they were 

likely expecting SFO to be in its usual configuration, which would include runway 28L being open 

for departures and arrivals and airplanes using taxiway F (as shown in figure 3) to reach the 

departure end of runway 28L. Because of the runway 28L closure on the night of the incident, 

airplanes were using taxiway C to depart from runway 28R. 

The flight crewmembers stated, during postincident interviews, that the taxiway C surface 

resembled a runway, which they believed was runway 28R. A cue supporting the crewmembers’ 

perception that they were aligned with runway 28R was the lighting from the airplanes on 

taxiway C. Specifically, the airplanes’ wingtip navigation lights would have partially resembled 

(width-wise) runway edge lighting.

100 Also, the airplanes’ flashing red beacon lights would have 

 99 The NTSB conducted an ASRS search to identify reports since 2010 related to flight crew confusion resulting 

from the depiction of ACARS messages and/or predeparture flight plan information. The NTSB found multiple reports

of altitude and lateral deviations in which the pilot cited the formatting of information as a related issue, which further 

indicates that information display improvements are needed for text-based resources. For more information, see 

exemplar cases (ACNs [accession numbers] 1282309, 1409095, 1414185, 1447318, 1540033, 1544364, and 820437) 

in the ASRS database (https://asrs.arc.nasa.gov/search/database.html, accessed September 14, 2018).

100 The second and third airplanes on taxiway C, an Airbus A340 and a Boeing 787, respectively, had wing spans 

of about 200 ft, which was also the runway 28R width. (The first airplane on taxiway C, a Boeing 787, also had a wing 

span of 200 ft, but the airplane was oriented perpendicularly to the taxiway. Thus, those wingtip lights would not have 

created the illusion to the incident flight crewmembers that they had aligned ACA759 with runway 28R.)
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been consistent with features associated with approach lighting. Another cue that would have 

supported the crew’s perception was the presence of runway and approach lights on runway 28R, 

which would also have been present on runway 28L when open. However, the runway and 

approach lights on runway 28L were off, and the construction lighting that was reported on the 

runway 28L surface had features that were consistent with ramp lighting. 

A psychological concept associated with perception and decision-making that can allow a 

mistaken assessment to persist is expectation bias, which refers to the manipulation of perceived 

elements to values consistent with a person’s expectation (Bhattacherjee 2001). A similar concept, 

confirmation bias, results from a tendency to primarily seek out confirming evidence of a belief 

while spending less effort seeking out negative evidence that can disconfirm the belief (Nickerson 

1998). Thus, expectation bias and confirmation bias can cause a person’s incorrect belief to persist 

despite available contradictory evidence. Both biases occur as part of basic information processing, 

and a person may not be actively aware of such biases at the perceptual level. In this report, the 

term “expectation bias” also describes the effects of confirmation bias.

Expectation bias is not a new phenomenon in aviation. The NTSB investigated numerous 

accidents and incidents that involved pilot errors resulting from expectation bias, particularly in 

night VMC when fewer cues were available to pilots to aid in airport and runway identification. 

For example, in January 2014, a Boeing 737 landed at the wrong airport in Branson, Missouri, in 

night VMC. The flight crew expected that the visually identified airport and runway were the 

intended destination and did not reference cockpit displays to verify the airport and runway. As a 

result, the airplane landed on runway 12 at M. Graham Clark Downtown Airport instead of 

runway 14 at Branson Airport. Also, in November 2013, a Boeing 747 landed at the wrong airport 

in Wichita, Kansas, in night VMC due to the flight crew’s expectation that the observed runway 

lights were from the intended landing runway at McConnell Air Force Base. Instead, the airplane 

landed at Colonel James Jabara Airport on a runway that was one-half the length of the intended 

landing runway. For both of these cases, cues that indicated the flight crew’s mistaken perception 

were available; however, those cues were not effectively used because the crewmembers’ 

expectation bias outweighed the available conflicting cues.101

For this incident, lighting aids generally associated with runways were not present on 

taxiway C. Specifically, although the flight crew perceived the taxiway to be the intended runway, 

the taxiway did not have a precision approach path indicator, touchdown zone lights, full-length 

edge lights, and approach lights.

102 However, the absence of these normally conspicuous features 

of a runway would have been difficult for the flight crewmembers to recognize because of their 

expectation bias and the inherent difficulty detecting omissions in the environment (the latter of 

which could have been mitigated if the flight crew had briefed the runway 28L closure). In

addition, features present along taxiway C were inconsistent with it being a runway. For example, 

although the presence of centerline lights along the full surface length was a cue that was consistent 

 101 For more information, see NTSB incident numbers DCA14IA037 and DCA14IA016, respectively. 

102 Air Canada’s stabilized approach criteria for a visual approach included vertical tracking on approximately a 

3° glidepath and using a visual approach slope indicator. Postincident interviews and airplane track data suggested 

that the captain used the precision approach path indicator located to the left of runway 28R for glidepath information, 

which was intended for airplanes approaching that runway. The availability of this glidepath information while the 

airplane was aligned with taxiway C would have supported the flight crew’s expectation that the airplane was aligned 

with runway 28R.
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with a runway, the taxiway centerline lights were green, as shown in figure 4.

103 (Runway 

centerline lights are white.) Also, flashing yellow in-pavement guard lights were present on 

taxiway C (also shown in figure 4), which would not have been present on a runway surface 

because the guard lights were designed to prevent a taxiing airplane from crossing onto a runway.

During postincident interviews, the flight crewmembers recalled seeing specific color 

cues, including the green taxiway centerline lights.104 However, the flight crew continued the 

approach despite this conflicting cue. Given that the general outline of airplane lights along 

taxiway C (in a straight line) had likely confirmed the crew’s expectation that the right-side surface 

was a runway, the omission of conflicting color cues in the crew’s assessment of the runway 

environment was consistent with the effects of expectation bias.105 The captain of DAL521 (the 

flight that immediately preceded the ACA759 into SFO) provided a similar assessment during 

postincident interviews. Specifically, the DAL521 captain stated that the airplane lights on 

taxiway C gave the impression that that surface could have been a runway.106

Although multiple cues were available to the flight crew to distinguish runway 28R from 

taxiway C, sufficient cues also existed to confirm the crew’s expectation that the airplane was 

aligned with the intended landing runway. As a result, once the airplane was aligned with what the 

flight crewmembers thought was the correct landing surface, they were likely not strongly 

considering contradictory information. The NTSB concludes that the cues available to the flight 

crewmembers to indicate that the airplane was aligned with a taxiway were not sufficient to 

overcome their belief, as a result of expectation bias, that the taxiway was the intended landing 

runway.

2.3.2.2 Flight Crew Recognition of Misalignment 

The captain stated that, while on final approach, he noticed lights going across what he 

thought was the runway 28R surface; this description is consistent with the in-pavement guard 

lights on taxiway C. Despite this cue indicating that the airplane was aligned with a taxiway, the 

captain’s expectation bias continued because of his assumption that the lights were associated with 

an airplane on the runway surface. The captain then asked the first officer to verify with the 

controller that the runway was clear. When the first officer looked up after prolonged heads-down 

time during the approach (see section 2.2.3), the airplane was lined up with the taxiway. However, 

the first officer presumed that the airplane was aligned with runway 28R due, in part, to his 

expectation that the captain would align the airplane with the runway, and the first officer did not 

 103 The NTSB is currently investigating a December 2017 incident involving a Horizon Air Bombardier Q400 

that was attempting to land on runway 6 at Pullman-Moscow Regional Airport, Pullman, Washington, at night. The 

runway was dark because its lights were out of service, and the airplane landed on the taxiway that was parallel to the 

runway despite the illumination of blue taxiway edge lights, which the flight crew perceived as dim white runway 

edge lights. For more information, see NTSB incident number DCA18IA081.

104 Taxiway lighting at YYZ, where the flight crew was based, was similar to the lighting on SFO taxiway C; 

both airports had green taxiway centerline lights and blue taxiway edge lights.

105 The airplanes’ wingtip navigation lights were red (left wing) and green (right wing), and the runway edge 

lighting was white.

106 The DAL521 captain also stated that, because the lights from the airplanes located on taxiway C were in a 

straight line, the airplane lights could have been perceived as centerline lights, which could confuse a flight crew.
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immediately recognize that the surface ahead was not the intended landing runway. When the first 

officer contacted the controller, the airplane was about 4,000 ft (0.66 nm) from the airport seawall.

As ACA759 continued to approach the airport seawall, the flight crew of the second 

airplane on taxiway C, PAL115, saw that ACA759 was lined up with taxiway C, and the PAL115 

crew turned on that airplane’s landing lights to alert the ACA759 crew. Video information showed 

that PAL115’s landing lights illuminated the surface in front of that airplane as well as the tail and 

side of the first airplane on taxiway C, UAL1. About this time, the UAL1 captain made the first of 

two transmissions, on the tower frequency, about the position of an airplane above the airport 

surface; these transmissions were also available cues for the incident flight crew to recognize 

ACA759’s misalignment.107

In addition, about this time, ACA759 descended to an altitude at which its landing lights 

would have illuminated the environment below. The appearance of airplanes on the surface

(especially given that the controller had just advised the flight crew that runway 28R was clear) 

and the lack of runway markings on the surface should have been additional cues indicating that 

the airplane was not aligned with runway 28R.

During postincident interviews, the captain and the first officer were unable to identify a 

specific triggering factor in the environment that led to the decision to initiate and call for, 

respectively, a go-around. However, all of the cues mentioned above occurred within 6 seconds 

before the initiation of the go-around (2355:59 to 2356:05). That period is consistent with the time 

for pilots to recognize a cue, make a decision, and execute an action. The NTSB concludes that 

multiple salient cues of the surface misalignment were present as the airplane approached the 

airport seawall, and one or more of these cues likely triggered the captain’s initiation of a 

go-around, which reportedly occurred simultaneously with the first officer’s call for a go-around. 

2.3.3 Role of Flight Crew Fatigue

The flight crew’s work schedule for the incident flight complied with the applicable 

Canadian flight time limitations and rest requirements (as discussed later in this section). Also, as 

previously stated, there was no evidence of sleep disorders or medical conditions that would have 

affected the quality of the captain’s and the first officer’s sleep in the days before the incident. 

During the 3 days before the incident, the captain had sleep opportunities of between 4.75

and 8 hours. The captain reported that he needed 6 to 7 hours of sleep to feel rested; thus, he did 

not likely have a chronic sleep debt, but might have had an acute sleep debt, at the time of the 

incident. Information about the first officer’s sleep opportunities was only available for the 2 days 

before the incident. During that time, the first officer had sleep opportunities of between 7 and 

7.5 hours (including naps). Because the first officer reported that he needed 8 hours of sleep to feel 

rested, it is possible that he was experiencing a slight acute or chronic sleep debt at the time of the 

 107 ACA759 was 500 ft (0.08 nm) from the airport seawall when the UAL1 captain made his first transmission 

about the position of an arriving airplane. When the UAL1 captain made his second transmission about the position 

of an arriving airplane, ACA759 was 450 ft (0.07 nm) beyond the seawall. The flight crewmembers recalled, during 

postincident interviews, that they did not hear specific transmissions on the tower frequency between the controller’s 

verification that the runway was clear and his go-around instruction.
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incident. However, other fatigue factors would have more strongly affected both crewmembers 

during the incident flight. 

The incident occurred about 2356, which was 0256 EDT according to the flight crew’s 

normal body clock time. The captain reported that he typically went to sleep after 0000 EDT, and 

the first officer reported that he typically began to feel tired about 2300 EDT. Thus, part of the 

incident flight occurred during a time when the flight crew would normally have been asleep. Also, 

0256 EDT approximates the start of the human circadian low period described in Air Canada’s 

fatigue information (0300 to 0500 body clock time). Even when a person is well rested, operating 

during this time of day increases the possibility of performance decrements (Caldwell 1997). 

Because the crewmembers were awake at a time that was opposite of their normal body clocks, 

they were more vulnerable to the effects of fatigue, which they reported experiencing after 

navigating through thunderstorms (about 0045 EDT on July 8) and between 0230 and 0300 EDT 

(on July 8). 

In addition, at the time of the incident, the captain had been awake for more than 19 hours, 

and the first officer had been awake for more than 12 hours. The first officer took advantage of an 

opportunity to nap for 1.5 hours before reporting for duty, but the flight crewmembers would likely 

not have been able to take advantage of controlled rest during the flight because they were dealing 

with thunderstorms during the first half of the flight and preparing for the approach during the 

second half of the flight.

108 The NTSB’s January 1994 study of flight crew-related major aircraft 

accidents indicated that fatigue related to lengthy periods of wakefulness could contribute to errors. 

Specifically, the study found that flight crewmembers who had been awake for more than 11 hours 

made significantly more procedural and tactical decision errors than those who had been awake 

for less time (NTSB 1994).

Among the performance decrementsresulting from fatigue is the inability to adapt behavior 

to accommodate new information, which could lead to higher susceptibility for expectation bias 

and increased difficulty of overcoming expectation bias once it occurs (Harrison and Horne 1999). 

The NTSB concludes that the captain and the first officer were fatigued during the incident flight 

due to the number of hours that they had been continuously awake and circadian disruption, which 

likely contributed to the crewmembers’ misidentification of the intended landing surface, their 

ongoing expectation bias, and their delayed decision to go around.

According to Canadian flight duty time and rest requirements (Canadian Aviation 

Regulations 700.16, “Flight Duty Time Limitations and Rest Periods”), the incident flight crew 

could have been on duty for 14 hours plus an additional 3-hour extension due to “unforeseen 

operational circumstances” (the delayed arrival of the inbound airplane due to weather).109 Thus, 

the incident captain and first officer could have been on duty until 0940 (1240 EDT) on July 8. 

The flight crewmembers completed their duty periods at 0032 (0332 EDT) on July 8, which 

 108 In addition, no evidence indicated that either pilot filed a fatigue report, which Air Canada requests from 

flight crewmembers who use the controlled rest policy.

109 According to Canadian Aviation Regulations 700.17, the “maximum flight duty time referred to 

in...700.16(1) may be exceeded if...the flight is extended as a result of unforeseen operational circumstances” 

Transport Canada’s “Guidance Material Concerning Flight Time and Flight Duty Time Limitations and Rest Periods,” 

S740.17, indicated that “unforeseen operational circumstances” relate to circumstances, including weather, that result 

in delays to a planned schedule.
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complied with Canadian regulations, but the regulations would have allowed the crewmembers to 

remain on duty for another 9 hours. 

The NTSB compared the Canadian flight time and rest requirements with those required 

by 14 CFR Part 117, “Flight and Duty Limitations and Rest Requirements: Flightcrew Members.” 

This comparison showed that the incident first officer’s flight and duty time and rest requirements 

would have complied with the provisions of Part 117.110 However, the flight and duty time and 

rest requirements for the captain, as a company reserve pilot, would not have complied with 

Part 117 regardless of whether he would have been considered to have been on long- or short-call 

reserve.111 (Although Part 117 addressed long- and short-call reserve, Canadian regulations did 

not make this distinction.) In addition, once assigned a flight, Canadian reserve pilots do not have 

any limitations on flight and duty time beyond those for line pilots.112

For pilots on long-call reserve, 14 CFR 117.21(d) indicated that a flight crewmember must 

receive a 12-hour notice of report time if the assigned flight begins before, and operates into, a 

flight crewmember’s window of circadian low.113 The incident captain was assigned to the flight 

to SFO at 0849 (1149 EDT) and reported for the flight at 1640 (1940 EDT), resulting in a notice 

period of 7 hours 51 minutes. Thus, the notice period would not have complied with US regulations 

for long-call reserve. Canadian regulations do not include a limitation on minimum notice of report 

time.

For pilots on short-call reserve, 14 CFR 117.21(c)(3) indicated that the total number of 

hours that a flight crewmember spends on reserve and on duty cannot exceed 16 hours (from the 

beginning of the reserve availability period). The incident captain went on reserve call at 0813 

(1113 EDT) on July 7. If the captain had been subject to the flight and duty limitations of Part 117 

(and considered to be on short-call reserve), he could operate a flight as long as his duty period 

ended before 0013 (0313 EDT) on July 8. Because of the 49-minute takeoff delay, the flight was 

projected to arrive at the gate at SFO at 0002 (0302 EDT) with an estimated duty end time of 0017 

(0317 EDT), which would have exceeded Part 117 requirements by 4 minutes. To comply with 

 110 Specifically, 14 CFR 117, Table B, “Flight Duty Period: Unaugmented Operations,” provided the maximum 

flight duty period limits (in hours) for line pilots. According to the table, the first officer would have been limited to 

12 hours of duty. He worked from 1640 to 0032 (1940 to 0332 EDT), which was a total of 7 hours 52 minutes.

111 According to 14 CFR 117.3, long-call reserve meant that, before beginning the rest period required by 

section 117.25, a pilot is notified to report for a flight duty period after the completion of the rest period, whereas 

short-call reserve meant a period of time in which a pilot is assigned to a reserve availability period. Generally, pilots 

on long-call reserve can be on call for a 24-hour period but, when scheduled, are released from duty and put on rest 

for a particular assignment. Pilots on short-call reserve are typically on reserve for a set amount of time each day and 

can be required to report to work with short notice. 

112 Transport Canada’s “Guidance Material Concerning Flight Time and Flight Duty Time Limitations and Rest 

Periods,” S740.21, “Flight Crew Members on Reserve,” indicated the following: “When a flight crew member is on 

reserve, an air operator must provide the flight crew member with the opportunity to obtain at least 8 consecutive 

hours [of] sleep in any 24 hours by one of the 3 methods indicated in the standard. When that flight crew member is 

contacted and required to report for duty during the period of reserve duty, the flight crew member is no longer 

considered to be on reserve but on duty.... This means that at anytime during the reserve period, a flight crew member 

can be required to start a 14 hour duty period (or longer depending on the applicability of those sections of 700.16 and 

720.16 which permit extended flight duty times). A flight crew member therefore must remain rested while on reserve 

such that they are able to cope with a full duty day if called.”

113 This section previously described the human circadian low period as between 0300 and 0500 body clock time, which was consistent with Air Canada’s fatigue guidance and academic research. According to 14 CFR 117.3, the 

window of circadian low occurs between 0200 and 0559 body clock time.
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regulations, the flight would have had to take off by 1854 (2154 EDT); however, the airplane took 

off at 1858 (2158 EDT).114 

Transport Canada indicated that its current flight and duty time regulations have been in 

effect since 1996. In 2010, the Canadian Aviation Regulatory Advisory Council Working Group 

began to update Canada’s regulations relating to fatigue. In 2014, Transport Canada released a 

draft of proposed new regulations and, in 2017, revised the draft proposed regulations.115

According to Transport Canada, the proposed regulations would better address the challenge of 

fatigue mitigation for pilots on reserve duty who are called to operate evening flights extending 

into their window of circadian low. 

The NTSB is aware that the Air Canada Pilots Association and Safer Skies, which 

comprises five unions in Canada, have been advocating for stricter rest requirements and flight 

time limitations to address pilot fatigue. However, Transport Canada has not yet finalized its

rulemaking in this area. The NTSB concludes that current Canadian regulations do not, in some 

circumstances, allow for sufficient rest for reserve pilots, which can result in these pilots flying in 

a fatigued state during their window of circadian low. Therefore, the NTSB recommends that 

Transport Canada revise current regulations to address the potential for fatigue for pilots on reserve 

duty who are called to operate evening flights that would extend into the pilots’ window of 

circadian low. 

2.3.4 Mitigations to Overcome Expectation Bias

Expectation bias occurs automatically and can be difficult to overcome once established 

because of its inherent strength. One way to overcome expectation bias is through training that 

stresses active questioning of observations and recognizing the presence of conflicting cues. About 

3 months before this incident, Air Canada implemented training on plan continuation and 

expectation bias. The training, which was provided to company pilots during annual recurrent 

training, comprised a video titled “Understanding Gut Feel,” which explained that a gut feeling 

was a sense of knowing things before a person could consciously know, communicate, or explain 

them. The video also explained that a gut feeling indicated a potential threat resulting from a 

situation that was different or strange or had changed. The NTSB reviewed the video and the 

planned PowerPoint presentation (to be introduced during the 2018/2019 training cycle) and found 

that they provided a good overview of the hazards of expectation bias and stressed monitoring and 

active questioning to mitigate the hazards. 

The incident captain and first officer did not receive this training before the incident flight 

and were scheduled to receive the training during their next annual recurrent training. Such training 

might have provided the captain and first officer with techniques to actively question their 

expectations, recognize their error, and act sooner. For example, during postincident interviews, 

the first officer stated that, when he looked up after the captain asked him to contact the controller 

to verify that the runway was clear, he thought that something was not right but could not resolve 

 114 If the flight had taken off at 1854 (2154 EDT), the captain would have been in compliance with Part 117 

because the delay in his actual duty end time (0032/0332 EDT) occurred due to events after takeoff.

115 Information about the proposed regulations is available at http://www.gazette.gc.ca/rp-pr/p1/2017/2017-07- 01/html/reg2-eng.html (accessed September 14, 2018).
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what he was seeing. The training video provided pilots with a process for assessing such a feeling. 

Specifically, the video presented a basic strategy for listening to gut feelings when evaluating a 

situation, as expressed by the acronym “LIVE”: listen (to signals), investigate (what has changed 

or is different), validate (test and confirm a theory about what is different), and express 

(communicate the concern to others). Although the flight crewmembers eventually recognized

(just before initiating the go-around) that the situation was not what they expected, they missed 

opportunities earlier in the approach (as indicated in sections 2.3.1 and 2.3.2) to reassess their 

expectations.

In addition to active questioning to overcome expectation bias, which may be prone to 

human limitations such as fatigue impairment, cockpit systems to improve crew positional 

awareness could provide a conspicuous cue of a misalignment with an intended landing surface. 

For example, an EGPWS option developed by Honeywell (known as RAAS) provides 

supplemental information to a flight crew about an airplane’s position relative to a runway during 

final approach. Studies showed that RAAS was effective in improving pilot performance and 

recognition of potential conflicts related to positional awareness (Khatwa 2004). 

As a result of its investigation of the August 27, 2006, wrong runway takeoff at Blue Grass 

Airport, Lexington, Kentucky, the NTSB recommended (A-07-45) that the FAA “require that all 

14 Code of Federal Regulations Part 91K, 121, and 135 operators install on their aircraft cockpit 

moving map displays or an automatic system that alerts pilots when a takeoff is attempted on a 

taxiway or a runway other than the one intended” (NTSB 2007). In a July 13, 2010, letter regarding 

Safety Recommendation A-07-45, the FAA provided details about a program to determine the 

effectiveness of cockpit moving map displays and described RAAS as “a product intended to 

improve situational awareness by providing pilots with aural advisories.” On April 9, 2014, the 

FAA stated that it drafted policy changes based on the lessons learned from the program but that 

it had no plans to require the technology requested in the NTSB’s recommendation. As a result, 

the NTSB classified Safety Recommendation A-07-45 “Closed—Unacceptable Action” on 

July 23, 2014.

Although the FAA has not mandated a system that provides supplemental information to a 

flight crew about an airplane’s position relative to a runway during final approach, the 

investigation of this incident found a safety benefit of such a system. Specifically, the NTSB asked 

Honeywell to conduct a simulation of the incident circumstances with an EGPWS that had the 

SmartLanding option, which had some features not provided by RAAS, including an alert for a 

potential taxiway landing. The simulation showed that the flight crew would have received the 

aural alert “Caution Taxiway, Caution Taxiway” when the airplane was at a radio altitude of 235 ft. 

At that point, the airplane would have been 2,600 ft (0.43 nm) from the airport seawall, and the 

flight crew would have been required to conduct a go-around because landing could not have been 

accomplished within the touchdown zone. Thus, such technology, if it had been installed on the 

incident airplane, could have helped the flight crew identify the surface misalignment and could 

have resulted in a go-around that was performed at a safer altitude (before the airplane was 

dangerously close to other airplanes), thereby improving safety margins.
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FAA data (as of August 3, 2018) indicated that 85% of wrong surface landings involved

general aviation airplanes.

116 Thus, additional information about an airplane’s position relative to 

a runway on final approach would benefit all pilots of airplanes landing at primary airports within 

Class B and Class C airspace.117 The NTSB concludes that flight safety would be enhanced if 

airplanes landing at primary airports within Class B and Class C airspace were equipped with a 

cockpit system that provided flight crews with positional awareness information that is 

independent of, and dissimilar from, the current ILS backup capability for navigating to a runway.

Although Honeywell’s SmartLanding system provides an alert if a potential taxiway 

landing is predicted, the NTSB understands (from conversations with the FAA) that there are 

current limitations on the widespread implementation of taxiway mapping.118 However, for a 

system that provides an alert when an airplane is not aligned with a runway surface, only the 

airplane position and the runway location are required, which are currently available in many 

transport-category airplanes. As a result, the NTSB believes that developing a system that provides 

an alert for non-runway surface alignment would be feasible in the near term with existing 

technology.

119 Therefore, the NTSB recommends that the FAA establish a requirement for 

airplanes landing at primary airports within Class B and Class C airspace to be equipped with a 

system that alerts pilots when an airplane is not aligned with a runway surface. 

The system described in Safety Recommendation A-18-25 would alert if an airplane was 

predicted to land on a non-runway surface, such as a taxiway. The NTSB recognizes that the 

technology for a system that provides an alert to pilots when an airplane is not aligned with the 

intended runway surface may not currently be available. Such a system would also need to define 

and compare information about the intended runway (from ATC clearance instructions and/or the 

airplane’s navigation system) with the airplane’s runway alignment on final approach.

 116 The FAA’s data also showed that 85% of wrong surface landings involved ATCT facilities that were 

considered to be between levels 4 and 9, indicating operations at small- or medium-sized ATCT facilities. These 

facilities might not have as many controllers and some of the equipment that level 10 through 12 ATCT facilities have. 

Thus, it is important for pilots operating at airports with level 4 through 9 ATCT facilities to have cockpit technology 

to aid in determining an airplane’s position relative to a runway on final approach.

117 According to the FAA, primary airports have more than 10,000 passenger boardings (enplanements) each 

year. Per the FAA’s Aeronautical Information Publication, Class B airspace is generally “surrounding the nation’s 

busiest airports in terms of IFR operations or passenger enplanements.” Class C airspace is generally “surrounding 

those airports that have an operational control tower, are serviced by a radar approach control, and that have a certain 

[minimum] number of IFR operations or passenger enplanements.”

118 The FAA indicated that one limitation is getting teams from (or contracted by) the FAA to every airport in 

the FAA’s database to survey taxiways, which would be a significant undertaking for a benefit that could be gained 

by installing a cockpit system that provides flight crews with positional awareness information by notifying them 

when an airplane is not aligned with a runway surface.

119 The NTSB is investigating the August 10, 2018, incident involving a Gulfstream IV airplane operated by 

Pegasus Elite Aviation as PEGJET flight 19 at Philadelphia International Airport, Philadelphia, Pennsylvania. The 

airplane, which was operating under 14 CFR Part 135 as a charter flight, was cleared to land on runway 35 about 

2050 EDT. During the visual approach, the airplane aligned with taxiway E. About 0.1 mile from the end of taxiway E, 

the pilot initiated a go-around, and the airplane overflew four air carrier airplanes on taxiway E during the climb. The 

incident airplane came within about 200 ft of the first airplane on the taxiway. At the time of the approach, the runway 

35 runway end identifier lights and the precision approach path indicator lights were out of service. The seven airplane 

occupants were not injured, and the airplane was not damaged. For more information, see NTSB incident number 

DCA18IA265. The circumstances of this incident demonstrate the importance of equipping airplanes with additional 

positional awareness technology when landing at primary airports in Class B and Class C airspace because of the risk 

to passengers in airplanes on a taxiway.
NTSB Aircraft Incident Report

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Honeywell’s systems are examples of existing technology that can accurately identify a 

runway surface when a pilot is on final approach.120 However, the NTSB is not aware of an 

automated system that has reliably demonstrated the ability to indicate whether an airplane is 

aligned with the specific runway for which it has been cleared. Such a system would further 

improve safety, especially at airports with parallel runways (which, according to the FAA’s wrong 

surface landing video, account for 75% of wrong surface landings), and provide a longer term and

more robust solution to wrong surface landings. Therefore, the NTSB recommends that the FAA 

(1) collaborate with aircraft and avionics manufacturers and software developers to develop the 

technology for a cockpit system that provides an alert to pilots when an airplane is not aligned with 

the intended runway surface and (2) once such technology is available, establish a requirement for 

the technology to be installed on airplanes landing at primary airports within Class B and Class C

airspace.

2.4 Reporting of the Incident Flight

Air Canada’s Flight Operations Manual stated that pilots were to report any accident, 

incident, emergency, or other safety-related event (which might require investigating, monitoring,

or tracking) to company flight dispatch as soon as possible. Examples of reportable events included

a significant navigation error, an unstable approach, a go-around, and any hazard that poses a direct 

threat to flight safety. Because all of these events occurred during the incident flight, the flight 

crew was required to report the incident, but Air Canada’s procedures at the time of the incident 

did not indicate what “as soon as possible” meant regarding the specific timeframe for reporting 

events.

The captain stated that he did not report the incident to company dispatch shortly after it 

occurred because he was “very tired” and it was “very late.”121 No available evidence indicated 

that the flight crew was aware at that point that ACA759 had overflown four air carrier airplanes

positioned along taxiway C; specifically, the crewmembers reported (during postincident 

interviews) that they did not see any airplanes on the taxiway, and the controller’s transmission to 

the crew about the misalignment did not mention any airplanes positioned on the taxiway. At 0747 

on the morning after the incident (July 8), the incident airplane (flown by another flight crew) 

departed SFO for Montreal, Canada. The incident captain and first officer met at 1100 on the 

morning after the incident to discuss the facts surrounding the event for the ASR. Air Canada 

records showed that the captain reported the event to dispatch at 1608. (At that time, the captain 

and the first officer would have been preparing for the flight from SFO to YYZ, which departed at 

1649.)

According to the dispatcher who received the initial notification about the event, the 

captain reported that the airplane was lined up with the wrong runway and that a go-around was 

performed. The dispatcher also stated that the captain’s report sounded “innocuous” given the 

amount of time (16 hours) that had elapsed since the event. However, Air Canada senior personnel 

first learned about the severity of the event—the proximity of the incident airplane to the airplanes 

 120 As stated in section 1.5.2, Garmin also has such a system available, and Rockwell Collins has a system in 

development.

121 The flight crew could have sent an ACARS message to report the event in a timely manner.
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on the taxiway—when the TSB sent an e-mail about 2200 EDT on July 9 that advised company 

personnel about the incident circumstances.122 The Air Canada A320 assistant chief pilot stated 

that, during a meeting on July 10, the flight crewmembers were told that ACA759 had overflown 

airplanes on a taxiway and that the crewmembers’ responses were “shock” and “surprise.” (The 

NTSB could not determine if the flight crew was aware, before this meeting, that ACA759 had 

flown over airplanes on taxiway C.) 

Air Canada’s director of corporate safety, investigation, and research stated that the 

incident airplane had flown about 40 hours before Air Canada senior officials became aware of the 

severity of the incident and realized that data from the airplane needed to be retrieved. However, 

by that point, the CVR information from the incident flight had been overwritten; the CVR 

installed in the incident airplane was designed to record 2 hours of operational data.123

CVR data for this incident would have provided additional information about the 

circumstances leading to the overflight, including the flight crew’s verbalized approach 

preparations (during approach set up and approach review) and the timing of pertinent 

conversations, such as when the captain asked the first officer to verify that the runway was clear

and when the first officer called for the go-around (compared with when the captain initiated the 

go-around). In addition, CVR information would have allowed the NTSB to (1) determine the 

timing and content of the flight crew’s conversations during final approach and for any 

conversations during and after the go-around and (2) assess the flight crew’s CRM, workload, and 

fatigue according to verbalized information and cockpit sounds. The NTSB concludes that, 

although the investigation into this incident identified significant safety issues, CVR information, 

had it been available, could have provided direct evidence regarding the flight crew’s approach 

preparation, cockpit coordination, perception of the airport environment, and decision-making.

2.5 Air Traffic Control Services

2.5.1 Air Traffic Control Tower Midnight Shift Staffing

On the night of the incident, the SFO ATCT was staffed with two controllers for the 

midnight shift, which began at 2230 and ended at 0630 the next day. Before the incident occurred, 

the controllers evaluated the traffic complexity and determined that the traffic volume would allow 

ATCT staffing to be reduced to a single-person operation (which was authorized for midnight shift 

staffing), with one controller working all positions in the tower cab and the other controller taking 

a recuperative break in the ATCT building. All control positions and frequencies were combined 

and operated from the local control position starting about 2349, which was 7 minutes before the 

incident occurred. 

The controller provided no indications, during a postincident interview, that the 

single-person operation affected his workload at the time of the incident. The controller stated that 

 122 As previously stated, the NTSB learned about this incident from the FAA at 1630 EDT on July 9 and notified 

the TSB at 1840 EDT the same day. 

123 In 2016, the International Civil Aviation Organization adopted a new standard calling for the installation of 

CVRs capable of recording the last 25 hours of aircraft operation on all aircraft manufactured after January 1, 2021, 

with a maximum certificated takeoff mass over 27,000 kg engaged in commercial transport.
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he would not combine positions unless he was comfortable and had some predictability about the 

tasks that he would need to perform. He also stated that the traffic volume on the night of the 

incident was normal and that he was not overly busy, even with the various frequencies that he 

was monitoring. The controller further stated that, if the traffic had become too busy or complex, 

he would have asked the other on-duty controller to return to the tower cab to assist. (The other 

on-duty controller returned to the tower cab at the end of his recuperative break at 0300 on July 8.)

In addition, analysis of the ATC voice recording indicated that the controller was calm and engaged 

during transmissions while ACA759 was on approach through the time that the UAL1 captain 

asked where the arriving airplane was going. Thus, the controller’s confusion that resulted from 

that transmission was most likely due to the situation and not his workload.

During postincident interviews, pilots of airplanes positioned along taxiway C suggested 

that ATCT staffing at the time of the incident was not adequate. Specifically, the UAL1118 captain 

stated that the tower controller “was performing way too many functions,” and a UAL863 pilot 

stated that the tower controller “should not have been the only controller working the entire 

airport.” Although no evidence indicated that ATC workload was a factor in this incident, the 

decision to combine local and non-local positions led to congestion on the tower frequency. 

Specifically, postincident interviews with the ACA759 flight crew indicated that the first officer 

waited to contact the controller (to confirm that the runway was clear) because the tower frequency 

was busy. The ATC voice recording showed that, during the 61 seconds before the flight crew’s 

query to the controller (from 2354:44 to 2355:45), there were ongoing communications between 

the tower and airplanes on the ground. 

Given the congestion on the tower frequency, it is possible that the ACA759 flight crew 

was waiting for a pause in the conversations between the controller and pilots of airplanes on the 

ground but then decided to break into a conversation to relay the crew’s concern about the 

perceived lights on the runway. The ATC recording showed that, when the ACA759 flight crew 

began its transmission to query whether runway 28R was clear, another pilot was talking to the 

controller. However, the controller clearly heard the transmission from ACA759 given that he 

checked the status of runway 28R and responded to ACA759’s query 1 second after the flight crew 

completed its transmission. 

According to postincident interviews, the captain’s request for the first officer to verify 

with the controller that runway 28R was clear occurred between the time that the airplane passed 

F101D (at an altitude of about 1,100 ft) and the time that the airplane reached an altitude of 600 ft. 

The airplane descended below 600 ft at 2355:07, so the flight crew did not break into the 

conversation until 38 seconds later. The airplane performance study for this incident found that, 

when the flight crew acknowledged the controller’s transmission that the runway was clear, the 

airplane was about 500 ft (0.08 nm) from the airport seawall. If the local (tower) and ground control 

positions had not been combined, the flight crewmembers would likely have had the opportunity 

to communicate their concern earlier. The NTSB concludes that, once the flight crewmembers 

perceived lights on the runway, they decided to contact the controller to ask about the lights; 

however, their query was delayed because of congestion on the tower frequency, which reduced 

the time available for the crewmembers to reconcile their confusion about the lights with the 

controller’s confirmation that the runway was clear.
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At the time of the incident, the SFO ATCT’s standard operating procedures described 

staffing requirements between 0630 and 2200 but did not provide such requirements between 2200 

and 0630 the next day. After the incident, the SFO ATCT acting air traffic manager issued 

guidance that stated that the local and ground control positions could not be combined before 0015. 

In response to the NTSB’s June 2018 query about the significance of the 0015 time (which is 

26 minutes after the reported time that all positions were combined on the night of the incident), 

the SFO ATCT operations manager indicated that 0015 was determined to be the earliest time that 

the positions could be combined based on normal traffic patterns, runway closures, administrative 

duties, and fatigue guidance. 

The SFO ATCT’s standard operating procedures also did not describe the procedures to be 

used (and not to be used) during the midnight shift, including those for single-person operations 

with combined positions. While working single-person operations on the night of the incident, the

controller applied LUAW procedures. However, FAA Order JO 7210.3Z stated that, when 

conducting LUAW operations, the local control position should not be combined with any 

non-local control position. Thus, LUAW procedures should not have been used at that point.

The controller was aware that LUAW operations should not be conducted when the local 

and ground control positions were combined. However, during a postincident interview, the 

controller stated, “when aircraft were on a 5-mile final and compressing, it was hard to fit in a 

departure from runway 1, without using LUAW.” The SFO acting air traffic manager stated that, 

if LUAW procedures were needed to efficiently move traffic, then traffic was “too busy to combine 

positions” into a single-person operation. Thus, the NTSB concludes that, although the use of 

LUAW procedures during single-person ATC operations was not a factor in this incident, the tower 

controllers should have delayed consolidating local and non-local control positions until LUAW 

procedures were no longer needed. The SFO acting air traffic manager stated that, after the 

incident, ATCT management had been reemphasizing the correct application of LUAW 

procedures. 

2.5.2 Airport Surface Surveillance Capability System

The ASSC system was designed to detect aircraft, vehicles, and other objects on the surface 

of an airport and present those images on a tower display. If the ASSC system detected a situation 

involving two tracks on a runway (aircraft/aircraft, aircraft/vehicle, or aircraft/other tangible 

object) and predicted an imminent collision, the system would produce a visual and an aural alarm. 

However, the ASSC system was not designed to predict an imminent collision involving an 

arriving airplane lined up with a taxiway, so the system functioned as designed and did not produce 

an alarm as ACA759 approached taxiway C. The system also functioned as designed during the 

12-second period when the ACA759 data block was not shown on the ASSC display (while the 

airplane was on short final) because the airplane was not in the system’s depiction area (coverage 

cone) during that time.

The controller stated that he noticed that the ACA759 data block had disappeared from the 

ASSC display, but he was not concerned about that because he could see the airplane out of the 
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tower cab windows.

124 The ACA759 data block reappeared on the ASSC display just before the 

flight crew initiated a go-around. Although the disappearance of the ACA759 data block from the 

ASSC display did not contribute to the incident, the current design of the ASSC system does not 

assist a tower controller in detecting potential taxiway landings. Such capability would be 

especially critical during nighttime and poor visibility conditions when a controller might not be 

able to visually observe an airplane lining up with a taxiway. 

The ASSC system was one of three ASDE systems in the national airspace system; the 

other two were ASDE-3 and ASDE-X. As a result of an October 2009 taxiway landing involving 

a Boeing 767 at Hartsfield Jackson Atlanta International Airport, Atlanta, Georgia, the NTSB 

recommended in March 2011 that the FAA expand ASDE-X capabilities to detect taxiway 

landings by taking the following actions:125 

Perform a technical review of Airport Surface Detection Equipment—Model X to 

determine if the capability exists systemwide to detect improper operations such as 

landings on taxiways. (A-11-12) 

At those installation sites where the technical review recommended in Safety 

Recommendation A-11-12 determines it is feasible, implement modifications to 

Airport Surface Detection Equipment—Model X to detect improper operations, 

such as landings on taxiways, and provide alerts to air traffic controllers that these 

potential collision risks exist. (A-11-13) 

On May 13, 2011, the FAA stated that “the ability to accurately predict that an aircraft is 

arriving to a taxiway is not possible without significant degradation in performance, timeliness, 

and accuracy of safety logic alerts for the more likely event of an aircraft arriving to a closed or 

occupied runway.” The FAA also stated that those performance tradeoffs existed at some airports 

with close parallel and offset threshold runways. The FAA further stated that implementing the 

recommended actions could (1) degrade the ASDE-X’s ability to provide correct and timely 

predictions to the associated parallel runway, (2) result in additional false alerts due to incorrectly 

predicting an aircraft landing on a taxiway, and (3) cause an actual alert to be missed if a runway 

is occupied at the time of an incorrect taxiway landing prediction. The FAA planned no further 

action regarding the recommendations. 

On September 14, 2011, the NTSB noted the FAA’s intent not to implement the 

recommended actions and recognized that the recommended review would need to consider 

performance tradeoffs, including those that the FAA discussed in its letter. However, the NTSB 

stated that the FAA determined, without performing the recommended review, that the 

performance tradeoffs would outweigh the safety benefits of providing the recommended 

 124 The primary responsibility of the local controller was to observe traffic outside of the tower cab window. The 

local controller could use the ASSC display and the radar display in the ATCT to augment visual observations of 

departing and arriving aircraft as well as aircraft and vehicle movements on runways, taxiways, and other parts of the 

movement area.

125 (a) For more information about this incident, see NTSB incident number OPS10IA001. (b) When these 

recommendations were issued, the ASSC system had not yet been developed.
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capabilities, which was not an acceptable response to the recommendations. Accordingly, the 

NTSB classified Safety Recommendations A-11-12 and -13 “Closed—Unacceptable Action.”

Since that time, technology has advanced considerably. The FAA’s February 2018 tests at 

SEA provided promising results regarding the potential of the ASDE-X system to detect and 

predict taxiway landings with only a negligible number of nuisance or false alarms. As previously 

stated, the ASDE-X system at SEA was configured to apply the same parameters that are used to 

predict a landing on a closed runway, and the tests showed that the system predicted the potential 

taxiway landings and provided an ASDE-X alarm when the airplane was within 20 seconds or 

3,000 ft of landing. The tests also showed that the alarm occurred with enough time for ATC 

personnel to respond, and no false alarms occurred during any of the approaches and taxiway 

landing scenarios. Thus, the results of the tests at SEA demonstrated that the concernsthat the FAA 

expressed in its response to Safety Recommendations A-11-12 and -13 appear to have been 

resolved. According to the FAA, a software enhancement, the taxiway arrival prediction capability,

was implemented at SEA in May 2018, and the FAA has a schedule to evaluate the remaining 

ASDE-X-equipped airports and implement the software enhancement, where feasible, by the end 

of fiscal year 2020.

The NTSB concludes that, if an airplane were to align with a taxiway, an automated ASDE 

alert would assist controllers in identifying and preventing a potential taxiway landing as well as 

a potential collision with aircraft, vehicles, or objects that are positioned along taxiways. The 

taxiway arrival prediction capability that was implemented at SEA (and was scheduled to be 

evaluated and implemented at other feasible ASDE-X locations) could be expanded to other ASDE 

system models (ASDE-3 and ASSC). Therefore, the NTSB recommends that the FAA modify 

ASDE systems (ASDE-3, ASDE-X, and ASSC) at those locations where the system could detect 

potential taxiway landings and provide alerts to air traffic controllers about potential collision 

risks.

2.6 Runway Closure Markers

A runway closure marker with a lighted flashing white “X” appeared at the approach and 

departure ends of runway 28L when it was closed, including on the night of the incident. The 

lighted “X” was consistent with the specifications in FAA AC 150/5345-55A, “Specification for 

L-893, Lighted Visual Aid to Indicate Temporary Runway Closure.” Although the runway closure 

marker might have been effective at preventing a takeoff from or a landing on runway 28L when 

it was closed (the specific risks that the lighted “X” was designed to address), the runway closure 

marker did not capture the attention of the incident flight crew as the airplane approached the 

airport while aligned with taxiway C. 

The lighted “X” runway closure marker was not designed to address the possibility that a 

flight crew could misidentify a runway surface due to ineffective signaling of a runway closure.

Although air traffic controllers can provide instructions to pilots about the closure of a runway, 

NOTAMs and ATIS broadcasts/messages are the primary means to inform pilots about runway 

closures. However, the information about runway closures provided in NOTAMs and ATIS 

broadcasts/messages is not necessarily a reliable means for ensuring that pilots are aware of the 
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closure information.126 As previously stated, although the runway 28L closure on the night of the 

incident was indicated in NOTAM and ATIS information that the incident flight crew received, 

that information was not effective in preventing the flight crew from misaligning the airplane 

during the approach to runway 28R.127 

The incident flight crew and the flight crew of DAL521 (which landed on runway 28R 

about 4 minutes before the incident occurred) stated that they did not see a lighted “X” on

runway 28L to indicate that it was closed. Given the current specifications for the runway closure 

marker, these flight crews likely did not see the “X” because their airplanes were not aligned with 

runway 28L. This situation highlights the need for a surface-based system with conspicuous and 

unambiguous visual cues that clearly indicate when a runway is closed, even if an approaching 

airplane is not aligned with the closed runway. Such a system would provide redundancy in case 

a flight crew does not review or retain runway closure information presented in NOTAMs or ATIS 

broadcasts/messages. Such a system would also be especially critical in situations involving the 

closure of a runway at an airport with parallel landing and taxiway surfaces (such as SFO). 

As previously discussed, cockpit mitigations (such as the use of navigational aids to back 

up a visual approach to the intended landing runway, as used by the DAL521 flight crew, and a 

system to provide additional positional awareness information) and ATC systems to alert 

controllers about a potential runway misalignment or taxiway alignment can provide multiple 

layers of protection to prevent a flight crew surface alignment error. In addition, when closed 

runways are marked conspicuously, the view outside the cockpit (during VMC) of an airport 

environment can assure flight crews that an airplane is correctly aligned with a parallel landing 

runway. 

If the incident flight crewmembers had observed the runway 28L closure marker early in 

the approach, their mistaken perception of the airport environment and alignment with taxiway C 

might not have occurred. Further, if the runway 28L closure marker had captured the incident 

flight crew’s attention later in the approach, that information might have been sufficient for the 

crewmembers to detect their mistaken perception and respond to the situation before the airplane 

reached the seawall. 

The NTSB is not aware of any operational or human factors research to improve the 

conspicuity of L-893 runway closure markers during the 31 years since the FAA issued a technical 

report about its research on runway closure markers (other than subsequent research on the use of 

light-emitting diode bulbs). During that time, widespread advances in lighting and control 

 126 The NTSB investigated a September 25, 2001, incident in which a Boeing 757 took off from a closed runway 

at Denver International Airport, Denver, Colorado. A system failure affected the availability of a NOTAM about the 

runway closure, and a controller cleared the airplane to take off from the closed runway. After that incident, the flight 

crewmembers stated that they were unaware that the runway was closed, and the captain did not recall if the runway 

closure information was included in the ATIS broadcast. As a result of the incident, the NTSB recommended that the 

FAA “require the use of physical devices or other means to clearly indicate to flight crews of arriving and departing 

aircraft that a runway is closed” (A-03-5). In response, the FAA issued AC 150/5370-2F, “Operational Safety on 

Airports During Construction,” which indicated that airports should use physical devices or other means to indicate 

to flight crews that a runway is closed. The NTSB classified Safety Recommendation A-03-5 “Closed—Acceptable 

Action” on January 30, 2012.

127 The NTSB has investigated other events in which pertinent NOTAM information was missed; for example, 

see NTSB accident numbers DFW07CA092, CEN12LA229, and CEN14FA505. 
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technology have occurred. These advances could allow more conspicuous attentional capture 

features to be incorporated into a runway closure marker’s design. Such features, which include 

varying the flash pattern, incorporating strobe lights, and/or creating apparent movement, might 

direct a pilot’s attention to a closed runway better than the current design of the lighted “X.”

The NTSB concludes that increased conspicuity of runway closure markers, especially 

those used in parallel runway configurations, could help prevent runway misidentification by flight 

crews while on approach to an airport. Therefore, the NTSB recommends that the FAA (1) conduct 

human factors research to determine how to make a closed runway more conspicuous to pilots 

when at least one parallel runway remains in use and (2) implement a method to more effectively 

signal a runway closure to pilots during ground and flight operations at night.
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3. Conclusions

3.1 Findings

1. None of the following were factors in this incident: (1) flight crew qualifications, which 

were in accordance with Canadian and US regulations; (2) flight crew medical conditions;

(3) airplane mechanical conditions; and (4) airport lighting, which met US regulations.

2. The first officer did not comply with Air Canada’s procedures to tune the instrument 

landing system (ILS) frequency for the visual approach, and the captain did not comply 

with company procedures to verify the ILS frequency and identifier for the approach, so 

the crewmembers could not take advantage of the ILS’s lateral guidance capability to help 

ensure proper surface alignment.

3. The flight crew’s failure to manually tune the instrument landing system (ILS) frequency 

for the approach occurred because (1) the Flight Management System Bridge visual 

approach was the only approach in Air Canada’s Airbus A320 database that required 

manual tuning of a navigation frequency, so the manual tuning of the ILS frequency was 

not a usual procedure for the crew, and (2) the instruction on the approach chart to manually 

tune the ILS frequency was not conspicuous during the crew’s review of the chart.

4. The first officer’s focus on tasks inside the cockpit after the airplane passed the final 

waypoint reduced his opportunity to effectively monitor the approach and recognize that 

the airplane was not aligned with the intended landing runway.

5. The flight crew-initiated, low-altitude go-around over the taxiway prevented a collision 

between the Air Canada airplane and one or more airplanes on the taxiway.

6. The controller responded appropriately once he became aware of the potential conflict.

7. Errors that the flight crewmembers made, including their false assumption that runway 28L 

was open, inadequate preparations for the approach, and delayed recognition that the 

airplane was not lined up with runway 28R, reflected breakdowns in crew resource 

management and led to minimal safety margins as the airplane overflew taxiway C.

8. The flight crewmembers’ lack of awareness about the runway 28L closure and the 

crewmembers’ previous experience seeing two parallel runways at San Francisco 

International Airport led to their expectation to identify two runway surfaces during the 

approach and resulted in their incorrect identification of taxiway C instead of runway 28R 

as the intended landing runway.
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9. Although the notice to airmen about the runway 28L closure appeared in the flight release 

and the aircraft communication addressing and reporting system message that were 

provided to the flight crew, the presentation of the information did not effectively convey 

the importance of the runway closure information and promote flight crew review and 

retention.

10. The cues available to the flight crewmembers to indicate that the airplane was aligned with 

a taxiway were not sufficient to overcome their belief, as a result of expectation bias, that 

the taxiway was the intended landing runway.

11. Multiple salient cues of the surface misalignment were present as the airplane approached 

the airport seawall, and one or more of these cues likely triggered the captain’s initiation 

of a go-around, which reportedly occurred simultaneously with the first officer’s call for a 

go-around.

12. The captain and the first officer were fatigued during the incident flight due to the number 

of hours that they had been continuously awake and circadian disruption, which likely 

contributed to the crewmembers’ misidentification of the intended landing surface, their 

ongoing expectation bias, and their delayed decision to go around.

13. Current Canadian regulations do not, in some circumstances, allow for sufficient rest for 

reserve pilots, which can result in these pilots flying in a fatigued state during their window

of circadian low.

14. Flight safety would be enhanced if airplanes landing at primary airports within Class B and 

Class C airspace were equipped with a cockpit system that provided flight crews with 

positional awareness information that is independent of, and dissimilar from, the current 

instrument landing system backup capability for navigating to a runway.

15. Although the investigation into this incident identified significant safety issues, cockpit 

voice recorder information, had it been available, could have provided direct evidence 

regarding the flight crew’s approach preparation, cockpit coordination, perception of the 

airport environment, and decision-making.

16. Once the flight crewmembers perceived lights on the runway, they decided to contact the 

controller to ask about the lights; however, their query was delayed because of congestion 

on the tower frequency, which reduced the time available for the crewmembers to reconcile 

their confusion about the lights with the controller’s confirmation that the runway was 

clear.

17. Although the use of line up and wait (LUAW) procedures during single-person air traffic 

control operations was not a factor in this incident, the tower controllers should have 

delayed consolidating local and non-local control positions until LUAW procedures were 

no longer needed.
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18. If an airplane were to align with a taxiway, an automated airport surface detection 

equipment alert would assist controllers in identifying and preventing a potential taxiway 

landing as well as a potential collision with aircraft, vehicles, or objects that are positioned 

along taxiways.

19. Increased conspicuity of runway closure markers, especially those used in parallel runway 

configurations, could help prevent runway misidentification by flight crews while on 

approach to an airport.

3.2 Probable Cause

The National Transportation Safety Board determines that the probable cause of this 

incident was the flight crew’s misidentification of taxiway C as the intended landing runway, 

which resulted from the crewmembers’ lack of awareness of the parallel runway closure due to 

their ineffective review of notice to airmen (NOTAM) information before the flight and during the 

approach briefing. Contributing to the incident were (1) the flight crew’s failure to tune the 

instrument landing system frequency for backup lateral guidance, expectation bias, fatigue due to 

circadian disruption and length of continued wakefulness, and breakdowns in crew resource 

management and (2) Air Canada’s ineffective presentation of approach procedure and NOTAM 

information.
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4. Recommendations

As a result of this investigation, the National Transportation Safety Board recommends the 

following:

To the Federal Aviation Administration:

Work with air carriers conducting operations under Title 14 Code of Federal 

Regulations Part 121 to (1) assess all charted visual approaches with a required 

backup frequency to determine the flight management system autotuning capability 

within an air carrier’s fleet, (2) identify those approaches that require an unusual or 

abnormal manual frequency input, and (3) either develop an autotune solution or 

ensure that the manual tune entry has sufficient salience on approach charts.

(A-18-23)

Establish a group of human factors experts to review existing methods for 

presenting flight operations information to pilots, including flight releases and 

general aviation flight planning services (preflight) and aircraft communication 

addressing and reporting system messages and other in-flight information; create

and publish guidance on best practices to organize, prioritize, and present this 

information in a manner that optimizes pilot review and retention of relevant 

information; and work with air carriers and service providers to implement 

solutions that are aligned with the guidance. (A-18-24)

Establish a requirement for airplanes landing at primary airports within Class B and 

Class C airspace to be equipped with a system that alerts pilots when an airplane is 

not aligned with a runway surface. (A-18-25)

Collaborate with aircraft and avionics manufacturers and software developers to 

develop the technology for a cockpit system that provides an alert to pilots when 

an airplane is not aligned with the intended runway surface, and, once such 

technology is available, establish a requirement for the technology to be installed 

on airplanes landing at primary airports within Class B and Class C airspace. 

(A-18-26)

Modify airport surface detection equipment (ASDE) systems (ASDE-3, ASDE-X, 

and airport surface surveillance capability) at those locations where the system 

could detect potential taxiway landings and provide alerts to air traffic controllers 

about potential collision risks. (A-18-27)
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Conduct human factors research to determine how to make a closed runway more 

conspicuous to pilots when at least one parallel runway remains in use, and 

implement a method to more effectively signal a runway closure to pilots during 

ground and flight operations at night. (A-18-28)

To Transport Canada:

Revise current regulations to address the potential for fatigue for pilots on reserve 

duty who are called to operate evening flights that would extend into the pilots’ 

window of circadian low. (A-18-29) 

BY THE NATIONAL TRANSPORTATION SAFETY BOARD

ROBERT L. SUMWALT, III

Chairman

EARL F. WEENER

Member

BRUCE LANDSBERG

Vice Chairman

T. BELLA DINH-ZARR

Member

JENNIFER HOMENDY

Member

Adopted: September 25, 2018
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Board Member Statements

Vice Chairman Landsberg filed the following concurring statement on October 4, 2018:

Vice Chairman Bruce Landsberg

Concurring Statement – Air Canada Taxiway Overflight Investigation

Concurring statements for SFO 

This incident report should be required reading for all pilots. Only a few feet of separation 

prevented this from possibly becoming the worst aviation accident in history. I have some 

reservations about some of our recommendations where we may have gone farther than necessary 

in some cases and not far enough in others. Time will tell if we got it right.

Recommendation A-18-24 to the FAA on Preflight Information:

From a human factors perspective, the preflight briefing system is archaic and poorly designed. 

This Air Canada crew missed two warnings about the closed runway in SFO, first in pre-departure 

and secondly, via ACARS before landing. Concerns about legal liability rather than operational 

necessity, drive the current system to list every possible Notice to Airmen (Notam) that could, 

even under the most unlikely circumstance, affect a flight. 

The current system prioritizes protecting the regulatory authorities and airports. It lays an 

impossibly heavy burden on individual pilots, crews and dispatchers to sort through literally 

dozens of irrelevant items to find the critical or merely important ones. When one is invariably 

missed, and a violation or incident occurs, the pilot is blamed for not finding the needle in the 

haystack! 

GPS and TFR notices often fall into the same category of overly complex and geographically 

irrelevant. The legalistic descriptions of TFRs and poorly-descriptive GPS outage areas are 

worthless to pilots and dispatchers without tremendous and time-consuming effort. A graphic 

presentation of where a flight might be restricted or impacted should be easily found on FAA’s 

website and suffice as an official brief. It should also be disseminated to other preflight or 

electronic Flight bag providers and be both accurate and timely. FAA should not be allowed to 

hide behind FSS using this disclaimer which currently appears on the official FAA TFR website. 

“Depicted TFR data may not be a complete listing. Pilots should not use the information on this website for flight planning 

purposes. For the latest information, call your local Flight Service Station at 1-800-WX-BRIEF.” 

The problem of hard-to-read codes and irrelevant information has been pointed out to the FAA for 

more than 15 years. In 2012 it was even put into Public Law 112-153 (Pilot’s Bill of Rights) and 

FAA was given one year to address. This incident makes it clear that there is much more work to 

be done. This is a safety issue that calls for urgent action. 

Finding 15 - Cockpit Voice Recorder: The Cockpit Voice Recorder (CVR), which would have 

provided much more information on what happened, unfortunately, was overwritten during normal 

operations. We are unable to say that the delay in reporting was deliberate and may never 

understand all the reasons behind the several other procedural failures that allowed this incident to 

get so close to catastrophe. The CVR would have provided a much better picture.
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As of this writing, the Board is considering a recommendation to extend CVR recording time to 

25 hours so that valuable data are not lost. However, cockpit image recording investigators provide 

another source of critical information, which will help to ensure that NTSB’s findings are 

comprehensive, and recommendations are well targeted. An image recorder recommendation was 

originally issued in 2000 (A-00-031). 

Non-punitive response - Image recording technology currently exists in every other mode of public 

transportation except commercial aviation. Some pilot groups are concerned about the right to 

privacy and that the information gathered will be used punitively. Workplace right-to-privacy has 

been extensively litigated but in safety-critical positions, it must take a backseat to human life. 

Most importantly, the data, gathered routinely before an accident, will be invaluable in preventing 

the next tragedy. This approach has been highly effective in FOQA. There may be some technical 

challenges to address but the payoff in increased safety and accountability will be significant. 

One of the strongest attributes of aviation is the concept of just culture or non-punitive corrective 

action. When a mistake is made, most people put their best foot forward and attempt to minimize 

a critical error, which is perfectly understandable. Some supervisors want to mete out sanctions to 

“teach a lesson” or to make an example of the crew. Unless someone is habitually error prone and 

they shouldn’t be in a safety-critical position, punitive response is completely ill-suited to critical 

performance environments. 

It’s almost a certainty this crew will never make such a mistake again and my hope is that they 

will continue to fly to the normal end of their careers. 

Everyone will gain much more from being introspective rather than judgmental on this incident. 

We should reward all aviation personnel and celebrate when someone self-confesses a mistake and 

learns from it. More importantly, the system learns from it and can take steps to eliminate event 

precursors. This is a key factor in the decades-long decline in commercial aviation’s accident rate. 

Fortunately, we’ll get another chance to put some fixes in place to make a highly improbable event 

even less likely to reoccur.

Recommendation A-18-25 – Automatic Warning of Wrong surface landing: The 

recommendation to require an automatic warning system for runway alignment for all aircraft is 

redundant. All commercial aircraft and nearly all GA aircraft flying into Class B and C airports 

are already equipped with runway alignment equipment – ILS, RNAV or FMS. Although Air 

Canada requires their crews to use systems that would have prevented the misalignment, the crew 

on the incident flight failed to program the system for unknown reasons. If the command bars and 

raw data do not align by 500 feet above ground level – something is clearly wrong, and a goaround is in order. This is basic checklist discipline – especially for night visual approaches.

In modern air carrier aircraft, the FMS autotunes the final approach aids so the pilots don’t have 

to. In this incident, the Bridge Visual Approach was the only one in Air Canada’s FMS system that 

did not have the autotune function. That certainly could have been misleading to a crew that was 

used to always having the approach tuned for them. It was an unusual procedure; charts for such 

procedures should highlight the need for verifying that electronic guidance is tuned. It might also 

be mentioned in the dispatch package.

Recommendation A-18-26 – New Equipment or Software: The recommendation to require a 

separate warning system in addition to the primary navigation system and be applicable to ALL 
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aircraft flying into Class B and C airspace (especially light, non-turbine Part 91) is far too broad 

and fails to put the focus on the heavier airplanes that are most likely to cause loss of life in a 

ground surface collision. 

I concur because safety takes preference but there should be reasonable risk management behind 

recommendations. There was not enough data to fully support a dissenting view at the Board 

meeting. An FAA risk assessment study was cited as the justification for this recommendation by 

noting that 85% of taxiway or wrong runway landings occurred during Part 91 operations. 

However, this study discussed before the Board meeting, noted in passing that GA incidents almost 

always occurred in daylight visual conditions when collision was highly unlikely. FAA’s 

assessment was that risk of a collision was “extremely improbable.”

My hope is that forthcoming software design will allow this recommendation to be implemented 

without much added complexity of additional hardware added to cockpits. Perhaps it can be a part 

of the Electronic Flight Bag (EFB). 

Recommendation A-18-29 to Transport Canada on Fatigue Rules: Fatigue continues to be a 

recurring factor in accidents and incidents. This captain had been awake for 19 hours. It’s estimated 

that he awoke around 0800 Eastern time; the incident occurred at 0300 ET the following day. 

While not technically on duty all that time, under Canadian regulations for reserve crew members, 

he could have been available for duty for another nine hours. Adjusting circadian rhythm, even 

with naps, is not a precise activity.

The captain’s statement as to why he did not make a timely incident report to dispatch after landing 

was that “It was very late” and he “was tired.” The captain was too tired to make a phone call to 

report the incident, but the rules required him to be able to fly a challenging night approach with 

139 passengers and crew behind him. If we expect solid human performance where lives are at 

stake, fatigue rules need to be based on human factors science and not on economic considerations. 

Member Weener joined this statement.
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Member Weener filed the following concurring statement on October 4, 2018:

Member Earl F. Weener, Ph.D.

Concurring 

As a longtime pilot and flight instructor, I understand that mistakes are inevitable for even the best 

aviators. Thus, it is critical that safety systems are instilled with redundancy and multiple layers 

which work effectively to mitigate, correct, or prevent these errors. I agree with findings and 

conclusions but wonder if they go far enough. We have focused on what can be done in the future 

to preserve the cockpit voice recorder. An opportunity to review a voice recording of events 

leading to an incident is invaluable but does not serve the same function as an immediate evaluation 

of a flight crew’s fitness for duty. 

In this event a commercial aircraft filled with passengers came within feet of striking another 

aircraft and causing a collision with several others on the ground. Over 1000 people were at 

imminent risk of serious injury or death. The commercial operator had policies in place that 

required the reporting of serious incidents and that would have removed the flight crew from 

service immediately and until they could be evaluated for flight readiness. However, the subjective 

observations of the crew as they flew over the aircraft on the ground and executed a go-around did 

not prompt them to report anything to their operational control until the next day. Moreover, they 

reportedly did not perceive the gravity of the situation, stating to NTSB investigator they did not 

descend below 400ft prior to initiating a go-around. According to the crew, they did not realize 

just how near they were to striking another aircraft.

In reality, the overflying crew may have been in a poor position to fully understand their proximity 

to disaster because of their perspective, looking down at night, and their workload, as they executed 

functions necessary to landing then undertook a go-around. And, although Air Canada procedures 

required incidents be reported as soon as possible, the crew was apparently unclear on the meaning 

of ASAP. They did not report the event to their Air Canada point of contact until the following 

day. The bottom line is that reliance on self-reporting in this instance resulted in a flight crew that 

only stopped flying that night because they had finished a shift. Had that not been the case, nothing 

would have stopped them from flying additional trips immediately following this incident. In this 

case, there turned out to be no medical issues or competency concerns with the crew. And, because 

they happened to be at the end of shift, any fatigue issues were resolved. However, I am not 

comforted because that despite a lack of immediate action, everyone made it home safely. I believe 

more robust measures should be in place to intervene when a dangerous situation become apparent. 

There was only one controller in the tower that night and his work load was significant. Yet, while 

he was expected to continue his solo operation, he also had unique knowledge of the events that 

had just occurred. It was the controller who called for the go-around, knew the Air Canada flight 

almost landed on an active taxiway, reported the Air Canada crew was shaken, and stated that he 

himself was other than calm after the event. When a pilot on the ground contacted the controller 

to report the Air Canada flight had gone right over him, the controller replied that he had seen it 

happen. Yet, the controller did not report the event in the system until the end of his shift. When 
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he did so, it was only as a go-around and he chose not to mark the event as significant when 

prompted by his reporting software. 

The pilots on the taxiway that evening had perhaps the best perspective of what occurred, and one 

even went so far as to switch on extra lighting to warn the approaching Air Canada flight away. 

Yet, faced with the need to continue their own flights and without any requirement for immediate 

reporting, the pilots on the ground took no immediate action prompting an intervention and 

evaluation of the Air Canada crew.

I am left concerned that post-incident forensic analysis of a cockpit voice recorder, while vital, 

cannot replace immediate, safety-focused interventions designed to take crews involved in near 

miss situations out of service until they can be assessed as safe to continue. Whether it is industry, 

the FAA, or airports that stand up a more effective “if you see something, say something” style 

system regarding dangerous operational behavior, it is clear to me that the need exists. 

Vice Chairman Landsberg and Member Dinh-Zarr joined this statement.
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5. Appendixes 

Appendix A: Investigation

The National Transportation Safety Board (NTSB) was notified of this incident at 

1630 eastern daylight time on July 9, 2017, by the Federal Aviation Administration (FAA). Two 

NTSB investigators traveled to San Francisco International Airport (SFO) on July 15. Investigative 

groups were formed in the areas of air traffic control and operations/human performance. 

Specialists were assigned to perform the readout of the flight data recorder at the NTSB’s 

laboratory in Washington, DC; conduct an aircraft performance study; and gather airport-related 

information.

Parties to the investigation were the FAA, the National Air Traffic Controllers Association, 

and Honeywell. In accordance with the provisions of Annex 13 to the Convention on International 

Civil Aviation, the Bureau d’Enquêtes et d’Analyses pour la Sécurité de l’Aviation Civile (BEA),

the NTSB’s counterpart agency in France, participated in the investigation as the representative of 

the state of design and manufacture, and Airbus participated in the investigation as a technical 

advisor to the BEA. Also, the Transportation Safety Board of Canada (TSB), the NTSB’s 

counterpart agency in Canada, participated in the investigation as the representative of the state of 

the operator and registry, and Air Canada, the Air Canada Pilots Association, and 

Transport Canada participated in the investigation as technical advisors to the TSB.
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Appendix B: Air Canada Postincident Actions

Air Canada reported, in e-mails to the NTSB dated April 17 through 20, 2018, that it took 

the following actions after the incident: 

• Developed a means for flight crews to use company tablets to highlight areas and make 

notes on digital flight releases. 

• Modified its procedures for the Flight Management System (FMS) Bridge approach to 

runway 28R at SFO. The instruction to tune the instrument landing system frequency was 

replaced with the instruction to use lateral and vertical navigation guidance to align an 

airplane with the runway centerline on short final. Also, the FMS automatically sequences

the missed approach procedure when the thrust levers are advanced to the

takeoff/go-around detent.

• Began assessing the use of airplane systems to provide aural and visual alerts if an airplane 

is not aligned with a runway. This capability is currently installed in company simulators 

as part of an effort to determine the appropriate system settings to be used during normal 

operations. 

• Upgraded the Airbus A320 simulator and increased its fidelity so that the simulator 

graphics could be set to replicate specific airports, including SFO. 

• Implemented familiarization training for operations to and from SFO for all pilots during 

recurrent training. 

• Implemented a learning management system module for all airports on the FAA’s Special 

Pilot-in-Command Qualification Airport list (including SFO), Air Canada restricted entry 

airports, and unique airports within Air Canada’s system.

• Reiterated the requirement to back up all approaches with electronic means when available. 

• Explained the meaning of “as soon as possible” (in revision 33 of the Flight Operations 

Manual, which was issued in May 2018) for reporting aircraft accidents, incidents, 

emergencies, and other safety events.

• Amended the arrival and approach briefing procedures (in revision 33 of the Flight 

Operations Manual) to ensure that the approach and runway lighting and visual aids 

expected for a runway are briefed.
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