NTSB/RAB-18/06

National Transportation Safety Board

Railroad Accident Brief

Southeastern Pennsylvania Transportation 

Authority Trolley Collision

Philadelphia, Pennsylvania

January 4, 2017

The Accident

On January 4, 2017, at 12:47 p.m. eastern standard time, Southeastern Pennsylvania 

Transportation Authority (SEPTA) trolley 9101 (struck trolley), traveling northwest on trolley 

route 10 with an estimated 47 passengers on board, stopped near the intersection of Lancaster 

Avenue and 38th Street, in Philadelphia, Pennsylvania, to offload passengers.1 SEPTA trolley 9085

(striking trolley), with 6 passengers on board, was also traveling northwest on trolley route 10, and

struck stopped SEPTA trolley 9101 in the rear at an estimated impact speed of 10 mph. First 

responders transported 40 passengers and both operators to local hospitals for treatment of minor 

injuries. The total estimated equipment damage to both trolleys was $60,000. At the time of the 

accident, the sky was partly cloudy, visibility was 10 miles, and the temperature was 54°F. Figure 1 

shows the accident scene.

Figure 1. Overhead view of the accident scene. (Photo courtesy of WPVI-TV.)

The National Transportation Safety Board (NTSB) recorder division received two digital 

video discs containing video footage from both the striking trolley and the struck trolley. In 

 1 In this accident brief, all times are eastern standard time.
SEPTA Trolley Collision

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addition, the SEPTA video recording system installed on each trolley recorded eight video cameras 

in color at a rate of 10 frames-per-second. No audio was recorded, however. Video footage reveals 

at 12:42:41 p.m., when the striking trolley (trolley 9085) exited the portal at 36th Street, between 

Market and Chestnut Streets, trolley 9101 was not in view.2 The operator of the striking trolley 

said that when he stopped at the 36th Street portal transit stop, he could see trolley 9101 ahead of 

him, waiting at a red traffic signal at the intersection of 36th and Market Streets. He said that he 

decided to increase the space between the trolleys because he knew that the lead trolley would pick 

up all of the passengers. Forward-facing video footage from the striking trolley revealed that it

passed through a facing point switch at 36th Street and Lancaster Avenue, without stopping, at 

12:45:54 p.m.

3 (See figure 2.)

Figure 2. Forward-facing image of the facing point switch at 36th Street and Lancaster Avenue.

SEPTA operating rule RDR-65 requires trolley operators to bring the trolley to a complete 

stop before traversing a facing point switch to ensure proper switch point alignment. The facing

point switch is circled in red in figure 3. According to the video, at 12:45:59 p.m., the striking 

trolley turned left onto Lancaster Avenue. After rounding the corner onto Lancaster Avenue, 

trolley 9101 was visible. By 12:46:19 p.m., the alternating, flashing red brake lights, and the 

steady, red tail lights of the struck trolley are visible in the video. At this time, trolley 9101 was at 

the intersection of Powelton Avenue and Lancaster Avenue and trolley 9085 was at the intersection 

of 37th Street and Lancaster Avenue.

 2 SEPTA uses a communication-based train control system inside a 2.5-mile tunnel section. This system provides 

speed enforcement, overspeed protection, and safe train separation between cars inside the tunnel. However, when a 

trolley exits the tunnel at either the 36th Street portal or the 40th Street portal, the trolley operator regains sole control 

of the vehicle’s operation. 3 A facing point switch is a railroad switch that is set to allow a train to face points as it passes them.
SEPTA Trolley Collision

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The striking trolley’s operator said that he continued along the route and noticed that 

trolley 9101 was about 1 block ahead as he approached 37th Street. Video footage revealed that 

trolley 9085 stopped about 1 trolley-length behind trolley 9101 at the intersection of Powelton 

Avenue and Lancaster Avenue at 12:46:35. He said that the traffic light at Powelton Avenue turned 

green and he used the master controller to accelerate within the same city block as trolley 9101.

Event recorder information from the striking trolley revealed that it had reached 23 mph within the 

same city block prior to impact. SEPTA Operating Rule RDR-61: Distance Spacing, prohibits 

trolleys from moving at speeds greater than 20 mph when there are other vehicles on the same city 

block. The rule states:

Under normal conditions outside of subway, light rail vehicles must operate at 

restricted speed not exceeding 20 mph when following another light rail vehicle 

within a city block. When closer than 200 feet (1/2 city block), light rail vehicles 

must operate at restricted speed not exceeding 5 mph. When conditions ahead 

require that a vehicle advance closer than the prescribed distance, operators must 

exercise extreme caution and operate at a speed that will enable them to stop their 

vehicle at least 2 car lengths behind the vehicle ahead.

The operator of the striking trolley told NTSB investigators that it was at this point that he 

began to feel groggy. He said that he blinked his eyes and saw trolley 9101, that was stopped 

behind a delivery truck, immediately in front of him. Although he slammed on his foot brake,

trolley 9085 struck the rear of trolley 9101 at a speed of 10 mph. (See figure 3.)

Figure 3. The view from the struck trolley's forward-facing camera, 2 seconds before impact.
SEPTA Trolley Collision

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Emergency Response

At 12:47:42 p.m., the operator of the struck trolley reported the accident to the SEPTA 

Control Center. Video recordings from the struck trolley revealed that a Philadelphia Fire 

Department vehicle, with emergency lights activated, appeared less than 5 minutes later. A 

Philadelphia Police Department car also arrived on scene.

The following events occurred from 12:52:41 p.m. until 1:17:19 p.m.:

• Multiple emergency services personnel and vehicles arrived on scene

• Emergency services personnel entered and removed passengers from trolleys 9101 

and 9085

• SEPTA’s transportation manager arrived on scene

• Police and firefighters spoke with the operator of the struck trolley

Forty people, including the two operators, were transported to local area hospitals in 

Philadelphia for treatment.

Operator of Struck Trolley

The operator of the struck trolley was qualified and was fully rested prior to going on duty 

at 6:54 a.m. on the day of the accident. He said the ground was wet in the early morning when he 

started his shift, and then dry after the sun came out.4

Operator of Striking Trolley

The operator of the striking trolley was working an additional shift for overtime on the day 

of the accident. The regular days off for the operator of the striking trolley were Tuesday and 

Wednesday; however, he called the dispatcher-in-charge the previous day to see if extra work was 

available.

5 After taking some cold medicine in tea around 9:00 a.m. that morning, he arrived at 

work at 11:30 a.m., checked in with the dispatcher, and confirmed with the transitioning operator 

that the trolley was in good condition before leaving the trolley depot at 11:54 a.m. A review of 

the trolley’s forward-facing video showed that the striking trolley operator was compliant with 

wayside signals in the tunnel.

SEPTA records reflected that the operator of the striking trolley was fully qualified. He had 

a Class B commercial driver’s license, which was due to expire on January 2, 2018. Vehicles 

included on the license were bus and “other rail”. He began working as a trolley operator for

SEPTA in 2014, and had an authority date of January 27, 2014, on his “Operator Qualification 

Record” for the Suburban/Light Rail Training section. SEPTA records documented the training 

 4 According to the Record of Decision for Federal Transit Administration (FTA)/SEPTA Postaccident Drug and 

Alcohol Testing form, the criteria for postaccident testing were not met. In addition, Federal Railroad Administration 

(FRA) toxicology testing was not performed on the operator of the struck trolley. 5 The area of responsibility for dispatchers at SEPTA differs some from the traditional “dispatcher” role. At 

SEPTA, dispatchers assign routes and check employees in to work.
SEPTA Trolley Collision

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history of the operator of the striking trolley. His primary routes included route 10 on the weekends 

and the route 15 on weekdays.

Human Performance Factors

The operator of the striking trolley reported feeling ill, with cold symptoms and a persistent 

cough, on the day prior to the accident. But, he said that after using a nighttime over-the-counter 

(OTC) cough and cold medication containing the sedating antihistamine diphenhydramine before 

going to sleep, he “felt a whole lot better” upon waking on the morning of the accident.6 At around 

9:00 a.m., prior to reporting for duty on the morning of the accident, he reported taking another 

dose of the same sedating medication. Although the day of the accident was one of his normal days 

off, the operator of the striking trolley had volunteered to work to earn overtime pay.

The SEPTA dispatcher said that he interacted with the operator of the striking trolley briefly 

on the morning of the accident when he verified the operator’s attendance, indicating that “I didn’t 

have a conversation with him, just checked him off.”

A review of recordings from the striking trolley’s inward-facing video recorder revealed 

performance decrements on the part of the operator of the striking trolley that could be contributory

with fatigue:

• While operating the trolley prior to the collision, the operator failed to open a door 

for a passenger, even though the passenger had pulled the stop request cord to 

indicate she needed to get off the trolley. The passenger had to speak to the operator 

to get his attention so that he would open the door.

• The operator of the striking trolley was traveling north on 36th Street when he was 

stopped by a red traffic light at the intersection of 36th Street and Lancaster Avenue, 

behind trolley 9101. When the light turned green, he proceeded through the light, 

following trolley 9101 west onto Lancaster Avenue, failing to maintain the required 

separation between the two trolleys.

• The operator of the striking trolley failed to stop and confirm the correct position

of the facing point switch at 36th Street and Lancaster Avenue.

• Inward-facing video of the striking trolley revealed that about 1 minute prior to the 

accident, the operator of the striking trolley was propping his head up with his hands 

while stopped at the Powelton Avenue traffic light. When the light turned green, he 

moved the trolley forward, but continued to rest his head on his hands. The operator 

of the striking trolley remained in this position until a few seconds before the 

collision with trolley 9101, at which point he sat up with his back fully against his 

seatback—a movement consistent with a bracing position, looked out the front 

window, and activated the trolley brake.

 6 Diphenhydramine is an antihistamine drug with useful sedative and anti-itching properties. It is a constituent in 

many OTC cough and decongestant remedies. Robert M. Youngson, Collins Internet-linked Dictionary of Medicine, 

2nd ed., (Glasgow, Scotland: Collins, 2005). According to Drugs.com, this is an ingredient in many over-the-counter 

medications such as Benadryl, Sudafed, and Theraflu.
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Medical Review and Toxicology

The 62-year-old operator of the striking trolley reported that he had head congestion and 

had not been sleeping well for about 5 days before the accident. He also reported feeling unwell

the day prior to the accident. He self-treated with an OTC nighttime cold medication containing 

the sedating antihistamine diphenhydramine the evening before and again in the morning about 

4 hours before the accident. He reported he was otherwise in good health and took no other 

medications. Postaccident alcohol breath testing and urine drug testing were negative for alcohol 

and other tested-for substances.7 Federal Transit Administration (FTA)-required postaccident urine 

toxicology protocol does not test for diphenhydramine.

The OTC sedating nighttime cold medication packet has warnings including “marked 

drowsiness may occur” and “be careful when driving a motor vehicle or operating machinery.”8

Diphenhydramine is a sedating impairing medication and peak drug levels (the highest levels of 

the sedating medication present in the blood after taking a dose of medicine) generally occur about 

2.5 hours following ingestion. The drug is eliminated from the body at various rates, but can take 

as long as 14 hours to eliminate half the dose of the drug in elderly adults.9 Compared to other 

antihistamines, diphenhydramine causes marked sedation; this is the rationale for its use as a sleep 

aid. Altered mood and impaired cognitive and psychomotor performance may also be observed. In 

fact, in a driving simulator study, a single 50 mg dose of diphenhydramine resulted in significant 

reported drowsiness and impaired driving ability more than a blood alcohol concentration of 

0.100 gm/dl.10 In the United States, drivers with blood alcohol concentrations of 0.08 gm/dl or 

greater are considered legally intoxicated.

Prior to the accident, the operator of the striking trolley demonstrated degraded operating 

performance consistent with fatigue. Therefore, it is likely that the driver’s degraded performance 

was the result of a combination of fatigue from the effects of his recent illness, not sleeping well 

the 5 nights prior to the accident, and the sedating effects of diphenhydramine. This combination 

of factors negatively affected his medical fitness for duty. The video recording from his trolley 

revealed the operator failed to apply the trolley brakes in time to avoid the collision.

The trolley operator had received training on restrictions for over-the-counter medications 

during initial training on January 27, 2014, almost 3 years before the accident, but refresher 

information was not provided. Since the accident, the SEPTA medical department has distributed 

and posted an advisory notice for OTC medications.

 7 LabCorp laboratory conducted FTA-mandated postaccident urine drug testing. Urine was tested for 

amphetamines, cocaine metabolites, opiates, phencyclidine, and marijuana metabolites. The cutoff levels are defined 

in Title 49 Code of Federal Regulations (CFR) 40.87. https://www.transportation.gov/odapc/part40/40-87. Accessed 

April 24, 2018. 8 CVS Health Severe Cough & Cold Drink Packets. http://www.cvs.com/shop/health-medicine/cough-coldflu/cough-cold-medicine/cvs-health-severe-cough-cold-drink-packets-prodid-1011693#!#Directions. Accessed 

July 25, 2017. 9 R.C. Baselt, “Diphenhydramine” in Disposition of Toxic Drugs and Chemicals in Man, 10th ed. (Seal Beach, 

California: Biomedical Publications, 2014), 684-687. 10 (a) Blood alcohol content is measured this way in the United States, Canada, and Australia. (b) J.M. Weiler, 

J.R. Bloomfield, G.G. Woodworth, A.R. Grant, T.A. Layton, T.L. Brown, D.R. McKenzie, T.W. Baker, and 

G.S. Watson, “Effects of fexofenadine, diphenhydramine, and alcohol on driving performance, a randomized, 

placebo-controlled trial in the Iowa Driving Simulator,” Annals of Internal Medicine 132, no. 5 (March 2000): 

354-363.
SEPTA Trolley Collision

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SEPTA Rail Operations Division Authority Standard Rules-4 “Fitness for Duty” states the 

following:

Employees must not perform any service while affected by any condition that could 

impair their ability to perform their duties properly. Such conditions include fatigue, 

use and effect of OTC medications, personal situations that impact alertness or 

one’s ability to concentrate, etc. Employees must notify the Authority Medical 

Department of any condition not already on record that could impair their ability to 

perform their duties.

The SEPTA Drug Free Workplace Manual provides employees with information about 

prescription and OTC medications, but does not specifically discuss the generic name of the 

medications used by the trolley operator. Further, the manual instructs employees to pay attention 

to labels indicating drowsiness or restrictions regarding driving and/or working around machinery, 

and to adjust their dosage and work schedule accordingly.

Collision Avoidance Systems

The communication-based train control (CBTC) sytem used inside of the tunnel to control 

the speed of the trolleys is not feasible in a roadway where the traffic flow of trolleys and vehicles 

intermingle. CBTC and positive train control sytems require track and wayside components that 

cannot be mounted in the roadway. The gross vehicle weight of a commercial vehicle can be up to 

80,000 pounds, while the weight of a trolley is about 58,000 pounds without passengers. Members 

of the NTSB investigative team researched the applicability of modern collision avoidance 

systems, such as those presently being used in the highway vehicle operating 

environment⸺⸺particularly those used by commercial carriers—to the trolley and streetcar 

operating environment. Currently, none of the collision avoidance systems technologies reviewed 

by the NTSB are being used in the trolley or streetcar operating environment. However, the NTSB 

believes that highway collison avoidance sytems may also be applied to trolleys.

There are several advanced collision avoidance technologies currently available in the 

marketplace that employ on-board sensor technologies such as cameras, radar, or lidar, to monitor 

the vehicles’ surroundings.11 Cameras, radar, and lidar that are installed on a vehicle can gather 

information directly by sensing their surroundings. These are called “vehicle-resident” systems 

because they are installed on one vehicle and do not communicate with other vehicles. These 

vehicle-resident collision avoidance technologies can use that information to warn the driver of 

impending danger so the driver can take appropriate action to avoid or mitigate an accident.

Automatic emergency braking (AEB) includes a range of systems that are designed to 

address rear-end accidents in which drivers do not apply the brakes or fail to apply sufficient 

braking power to avoid or mitigate a collision. AEB systems use vehicle-resident sensors—such 

 11 A lidar device detects objects and determines their position, velocity, or other characteristics by analysis of 

pulsed laser light reflected from their surfaces. 
SEPTA Trolley Collision

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as radar, cameras, or lidar—to detect an imminent collision, warn the driver, and engage the brakes, 

should the driver take insufficient action.

12

The technology in these collision avoidance systems have proven to be effective and are 

currently being installed in some new motor vehicles.13 NTSB believes if the applicable avoidance 

technologies are also applied to trolley systems, the occurrences of rear-end collisions, such as this 

one, will be significantly reduced.

Previous NTSB Reports

NTSB has a long history of investigating rear-end-collisions amongst highway vehicles. 

Since 1995, NTSB has encouraged technicological countermeasures to mitigate such accidents. In 

2001, NTSB released a Special Investigation Report on this subject and made several safety 

recommendations to federal agencies and vehicle manufacturers.14

Continued technological advancements in collision avoidance systems and delays in the 

implementation of previous NTSB safety recommendations prompted another Special 

Investigation Report in May 2015.15 In this report, the NTSB “examined the prevalence of rear-end 

crashes, their cost in lives lost, and the extent to which collision avoidance systems could have 

prevented or mitigated such crashes.”16 As a result of this special investigation report, the NTSB 

issued the following recommendation to the National Highway Traffic Safety Administration

(NHTSA):

Complete, as soon as possible, the development and application of performance 

standards and protocols for the assessment of forward collision avoidance systems 

in commercial vehicles. (H-15-5)

Although NHTSA has advised the NTSB that it is researching the development of collision 

avoidance systems and supporting technologies, the NTSB has responded that it believes that 

NHTSA has not done enough to address this issue. Hence, the NTSB has reiterated 

Safety Recommendation H-15-5 in August 2015, March 2017, and October 2017.17 This safety 

recommendation is currently classified Open—Unacceptable Response.

 12 National Highway Traffic Safety Administration, “Manufacturers make progress on voluntary commitment to 

include automatic emergency braking on all new vehicles,” news release, December 21, 2017. 

https://www.nhtsa.gov/press-releases/nhtsa-iihs-announcement-aeb, accessed May 24, 2018. 13 National Highway Traffic Safety Administration, “Automatic emergency braking.” 14 National Transportation Safety Board, Vehicle- and Infrastructure-based Technology for the Prevention of 

Rear-End Collisions, SIR-01/01 (Washington, DC: National Transportation Safety Board, 2001). 15 National Transportation Safety Board, The Use of Forward Collision Avoidance Systems to Prevent and 

Mitigate Rear-End Crashes, SIR-15/01 (Washington, DC: National Transportation Safety Board, 2015). 16 NTSB Safety Recommendation Letter to Passenger Vehicle, Truck-Tractor, Motorcoach, and Single-Unit Truck 

Manufacturers for NTSB Safety Recommendations H-15-8 and H-15-9, June 8, 2015. 17 (a) National Transportation Safety Board, Multivehicle Work Zone Crash on Interstate 95, Cranbury, 

New Jersey, June 7, 2014, HAR-15/02 (Washington, DC: National Transportation Safety Board, 2015); (b) National 

Transportation Safety Board, Motorcoach Collision With Crash Attenuator in Gore Area, US Highway 101, San Jose, 

California, January 19, 2016, HAR-17/01 (Washington, DC: National Transportation Safety Board, 2017); 

(c) National Transportation Safety Board, Motorcoach Collision With Combination Vehicle After Traffic Break on 

Interstate 10, Palm Springs, California, HAR-17/04 (Washington, DC: National Transportation Safety Board, 2017).
SEPTA Trolley Collision

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This technology is also applicable to the trolley-streetcar operating environment. 

Therefore, the NTSB recommends the American Public Transportation Association develop 

performance standards for the use of forward collision avoidance systems technology for light-rail 

vehicles operating on an urban street environment.

NTSB Postaccident Actions

On January 8, 2017, NTSB investigators completed sight distance observations and four 

brake performance tests on the striking trolley at the accident location. NTSB investigators 

observed that the track brake did not function when using the emergency brake push-button during 

brake performance tests.

18 Although this defect was discovered during the postaccident testing of 

the braking systems, this flaw did not contribute to the accident because the operator used the brake 

pedal to apply the emergency brake, as indicated on video from inside the trolley.

After postaccident brake performance testing, NTSB investigators released the striking 

trolley to the Elmwood maintenance facility to troubleshoot the inoperative track brake. They

removed the inspection panel under the operator console and found a broken electrical switch no 

longer attached to the emergency brake push-button. NTSB investigators contacted the 

manufacturer of the emergency brake push-button electrical switch, WABTEC Corporation 

(WABTEC), concerning this issue. WABTEC published a service bulletin that explained the proper 

installation and adjustment of the electrical switch and distributed it to its customers who use that

design in rail transit vehicles.

In response to the SEPTA push-button electrical switch failure, the NTSB issued a safety 

alert to warn rail transit agencies, the Federal Transit Administration, (FTA) and the state safety 

oversight agencies (SSOA) of the potential failures for similar vehicles of a comparable design.19

This safety alert helps rail transit operators:

• identify vehicles that may use comparable designs

• prevent or reduce the severity of accidents that may result from an emergency brake 

push-button electrical switch failure

In addition, the NTSB issued the following early safety recommendation to the FTA on 

May 17, 2017.

Utilize your authority under Title 49 Code of Federal Regulations 670.25, and issue 

a general directive that would require all state safety oversight agencies to direct 

rail transit agencies to periodically test the performance of all of their rail transit 

vehicle braking systems to detect potential latent system failures. (R-17-04)20

On August 8, 2017, the executive director of the FTA told the NTSB that the FTA plans to 

develop and issue a general directive that will be published in the Federal Register. Safety 

Recommendation R-17-04 is currently classified Open—Acceptable Response.

 18 For more information, see the Mechanical Factual Report in NTSB Docket DCA17FR003.

19 National Transportation Safety Board, Rail Transit Vehicle Emergency Brake Push-button Electrical Switch 

Failure, SA-063, April 2017. 20 National Transportation Safety Board, Rail Transit Vehicle Safe Braking, RSR 17/01 (Washington, DC: 

National Transportation Safety Board, 2017).
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SEPTA Postaccident Actions

Since the accident, SEPTA has implemented or began the process of implementing the 

following:

• Included a review of SEPTA Rail Division Rule 61 – Following Light Rail Vehicles 

in future recertification classes to ensure that all trolley operators are familiar with 

the spacing requirements associated for following trolleys in street operation.

• Created an engineering modification for the trolley emergency brake push-button 

to correct the switch failure discovered during testing. Installing the modification 

in both the single-end and double-end fleets.

• Issued a notice to all employees discussing best practices and reiterating SEPTA’s 

requirements for being mindful of taking OTC medications and the potential effects 

of their use on safety-sensitive employees.

• Modified the reporting windows at operator reporting locations so that district 

dispatchers and/or clerk receivers can observe operators without a glass divider in 

place.

• Trained all clerk receivers in drug and alcohol recognition so that they may assist 

district dispatchers in observing operators as they report for duty.

• Worked with third party vendors on the development of a collision avoidance 

warning system for the current street-running trolley fleet. Investigating the 

technology for future trolley procurements.

• Posted advisory notices that discuss the hazards associated with OTC medication, 

specifically identifying diphenhydramine, the sedating medication used by the 

operator of the striking trolley.21

Probable Cause

The National Transportation Safety Board determines that the probable cause of this 

accident was the failure of the operator of the striking trolley to slow and stop his trolley before 

colliding with the stopped trolley because of his impairment from fatigue and the sedating effects 

of the repeated doses of over-the-counter antihistamine diphenhydramine. Contributing to the 

operator’s fatigue was his illness, which negatively affected his medical fitness for duty.

 21 “Notice Medical Department Advisory for Over the Counter Medications” can be found in the Medical Factual 

Report – Attachment 2 in the accident docket, DCA17FR003.
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Safety Recommendation

The National Transportation Safety Board makes the following safety recommendation:

To the American Public Transportation Association:

Develop performance standards for the use of forward collision avoidance systems 

technology for light-rail vehicles operating on an urban street environment.

(R-18-023)

BY THE NATIONAL TRANSPORTATION SAFETY BOARD

ROBERT L. SUMWALT, III EARL F. WEENER

Chairman Member

BRUCE LANDSBERG T. BELLA DINH-ZARR

Vice Chairman Member

JENNIFER HOMENDY

Member

Adopted: September 11, 2018

For more details about this accident, visit www.ntsb.gov/investigations/dms.html and 

search for NTSB accident ID DCA17FR003.

The NTSB has authority to investigate and establish the facts, circumstances, and cause or 

probable cause of a railroad accident in which there is a fatality or substantial property damage, or 

that involves a passenger train. (49 U.S. Code § 1131 - General authority)

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 Code of Federal Regulations, Section 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 United States Code, 

Section 1154(b).