National Transportation Safety Board

Washington, D.C. 20594

Safety Recommendation Report

Extended Duration Cockpit Voice Recorders 

Accident Number: Multiple (see tables 1 and 2)

Location: Multiple (see tables 1 and 2)

Date: Multiple (see tables 1 and 2)

Adopted: October 2, 2018

The National Transportation Safety Board (NTSB) is providing the following information 

to urge the Federal Aviation Administration (FAA) to take action on the safety recommendations 

issued in this report. These recommendations address the need to install cockpit voice recorders 

(CVR) with a minimum 25-hour recording capability on all newly manufactured airplanes required 

to have a CVR and retrofit these CVRs on existing aircraft required to have flight recorders. These 

recommendations are derived from the NTSB’s experiences with investigations that lacked access 

to relevant CVR data. Information supporting these recommendations is discussed below.

Background and Analysis

The NTSB has longstanding concerns about the availability of CVR information following 

events that meet the reporting criteria of 49 Code of Federal Regulations 830.5. The availability 

of relevant CVR data is also a recurring issue in our safety investigations of events that don’t meet 

reporting criteria but turn out to have safety significance (for example, the July 7, 2017, incident 

at San Francisco International Airport in which the flight crew of an Airbus A320 lined up to land 

on a taxiway and overflew four air carrier airplanes on the taxiway awaiting takeoff).

CVRs are among the most valuable tools used for accident investigation. Information such 

as flight crew verbalizations of intentions and coordination, as well as pilots’ awareness of the 

state of the aircraft and cockpit information, allows investigators to more comprehensively assess 

accident/incident factors. These factors include flight crews’ procedural compliance, distraction, 

decision-making, workload, fatigue, and situational awareness. Ultimately, CVRs provide unique 

information with which the NTSB can conduct more thorough investigations to more effectively 

target safety recommendations. CVRs have a current standard recording duration of only 2 hours 

and, unfortunately, recent safety investigations have been hampered because relevant portions of 

the recordings were overwritten.1

 1 In response to instances of overwritten data on CVRs with a required recording duration of 30 minutes, the 

NTSB issued Safety Recommendation A-96-171 on December 20, 1996, which superseded A-95-23, asking the FAA 

to “require that all newly manufactured [CVRs] intended for use on airplanes have a minimum recording duration of 

2 hours.” As a result of the final rule implementing the recommended requirement, Safety Recommendation A-96-171 

was classified “Closed—Acceptable Action” on October 14, 2008. On March 9, 1999, the NTSB issued A-99-16, 
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58452 ASR-18-04

In 2013, the European Aviation Safety Agency (EASA) proposed an amendment that, after 

January 1, 2019, requires newly manufactured, large commercial aircraft to carry a CVR capable 

of recording the last 15 hours of aircraft operation.2 Considering the comments received on the 

proposed amendment and after technical review, the European Union, in 2015, extended the 

requirement to 25 hours with an implementation date of January 1, 2021.3 In 2016, after receiving 

recommendations from member states to extend the required duration of CVRs, the International 

Civil Aviation Organization (ICAO) 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. In its rationale, ICAO emphasized the value of CVR recordings in analyzing human 

factors and other sounds. ICAO also noted that extended duration CVRs are necessary to cover the 

longest duration flights, including pre- and postflight activities, delays, and the time required to 

secure the recordings. The CVR technical standard for flight recorders already has provisions for 

a 25-hour CVR.4

As discussed in this report, the NTSB believes that our ongoing experience with 

overwritten CVR recordings demonstrates the limitations of the current 2-hour recording 

requirement, particularly in cases where relevant data were overwritten due to (1) a delay in 

reporting a safety event that was not immediately recognized to be of a serious nature until further 

data review; (2) a failure to immediately deactivate the CVR following arrival after a safety event;

or (3) the time remaining in the flight after a safety event, which exceeded the CVR’s 2-hour 

recording duration.

In the event of a major or catastrophic accident, the CVR is typically deactivated due to a 

loss of electrical power (without manual intervention), and the relevant audio that was recorded 

before the accident is preserved.5 However, following less severe events in which the airplane’s 

electrical system remains functional, pilots or others must act to deactivate the CVR as promptly 

as possible after landing to preserve the most relevant audio. Sometimes a delay in reporting an 

event to the FAA, the NTSB, or the operator also results in a significant delay in actions to 

safeguard recorder data. Lacking these data means that an investigation may not identify issues 

that played a role in the event, which could result in a similar—or worse—occurrence in the future. 

 asking in part, that the FAA “require retrofit after January 1, 2005, of all [CVRs] on all airplanes required to carry 

both a CVR and a flight data recorder with a CVR that...is capable of recording the last 2 hours of audio.” As a result 

of the final rule, which the NTSB believed represented an acceptable alternate method of compliance with the 

recommended action, Safety Recommendation A-99-16 was classified “Closed—Acceptable Alternate Action” on 

October 14, 2008.

2 Notice of Proposed Amendment 2013-26, “Amendment of requirements for flight recorders and underwater 

locating devices.”

3 Official Journal of the European Union. Commission Regulation (EU) 2015/2338 of 11 December 2015 

amending Regulation (EU) No 965/2012 as regards requirements for flight recorders, underwater locating devices and 

aircraft tracking systems.

4 “Minimum Operational Performance Specification for Crash Protected Airborne Recorder Systems,” ED-112A,

European Organization for Civil Aviation Equipment.

5 Most CVR installations are designed to operate whenever the airplane’s electrical system is on, and the CVR 

continually overwrites the oldest data stored on the tape or memory module.
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In an August 2002 safety recommendation letter to the FAA, the NTSB identified delays 

or failures to deactivate CVRs after reportable events as a major factor in the systemic problem of 

retaining relevant data. As a result, the NTSB recommended the following to the FAA:

Require that all operators of airplanes equipped with a [CVR] revise their 

procedures to stipulate that the CVR be deactivated (either manually or by 

automatic means) immediately upon completion of the flight, as part of an approved 

aircraft checklist procedure, after a reportable incident/accident has occurred. 

These procedures must also ensure that the recording remains preserved regardless 

of any subsequent operation of the aircraft or its systems. Any doubt as to whether 

or not the occurrence requires notification of the [NTSB] must be resolved after 

steps have been taken to preserve the recording. (A-02-24)

In response, the FAA issued Notice N8400.48, “Cockpit Voice Recorder Deactivation 

After a Reportable Event,” advising air carriers to add a checklist line item stipulating that the 

CVR be deactivated (either manually or automatically) immediately upon completion of a flight 

having a reportable incident/accident. The expanded checklist procedures also included an item 

for flight crews to notify maintenance personnel if the CVR is deactivated so CVR data aren’t lost 

on a subsequent flight. The notice also specified that any doubt as to whether an occurrence 

required NTSB notification be resolved after steps have been taken to preserve the recording. On 

October 6, 2003, noting that the FAA’s actions met the recommendation’s intent for Part 121 and 

Part 135 operators (but not Part 91 operators), the NTSB classified Safety 

Recommendation A-02-24 “Closed—Acceptable Alternate Action.”

The NTSB notes that even with the issuance of Notice N8400.48, several NTSB 

investigations have lacked access to pertinent CVR data following safety events; fourteen such 

instances have occurred since 2003 (see table 1). The NTSB recognizes that preserving CVR data 

is often challenging because the significance of an event is not readily apparent to the flight 

crew or air traffic controllers when it occurs. In some cases (examples identified in the following 

table), the aircraft operation time between the event’s occurrence and NTSB notification or the 

NTSB’s full awareness of the nature of the event exceeds 25 hours, so even an extended duration 

CVR wouldn’t retain the pertinent data. However, such cases highlight the need for layers of 

protection in mitigating the loss of CVR information.

Table 1. Safety Events for Which Pertinent CVR Data Were Overwritten

Date Event type NTSB # Location Length of 

CVR

Event Description

6/21/2018 Incident OPS18IA015 Chicago, IL 2 hr Runway excursion

4/18/2018 Accident DCA18LA163 Atlanta, GA 2 hr Engine fire

7/7/2017 Incident DCA17IA148 San Francisco, CA 2 hr Taxiway line-up and 

overflight of 4 air carrier 

airplanes by an Airbus 

A320

(46-hour notification delay)

5/9/2014 Accident CEN14LA239 Columbus, OH 2 hr Ground engine fire

9/12/2013 Incident CEN13IA563 Austin, TX 2 hr Loss of pitch control during 

takeoff

(4-day notification delay)
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Date Event type NTSB # Location Length of 

CVR

Event Description

7/31/2012 Incident CEN12IA502 Denver, CO 2 hr Bird strike

12/1/2011 Accident WPR12LA053 Oakland, CA 2 hr Enroute turbulence

2/9/2011 Incident ENG11IA016 Minneapolis, MN 2 hr Tailpipe fire following push 

back

11/23/2010 Accident WPR11LA058 Salt Lake City, UT 2 hr On ground collision with 

tow tractor

6/21/2011 Incident ENG11IA035 Atlanta, GA 2 hr Engine fire

6/28/2010 Accident CEN10LA363 Pioneer, LA 2 hr En route turbulence

12/13/2009 Incident DCA10IA015 Charlotte, NC 2 hr Wing tip strike during 

landing

6/29/2007 Incident LAX07IA198 Los Angeles, CA 2 hr Blown tires on takeoff

3/21/2006 Incident DEN06IA051 Denver, CO 2 hr Tail strike on landing

10/16/2003 Accident MIA04LA004 Tampa, FL 2 hr Taxiway excursion

6/3/2002 Accident DCA02MA039 Subic Bay, 

Philippines

2 hr Abrupt maneuver due to 

ground proximity warning 

system alert and elevator 

damage

6/2/2002 Accident DCA02MA042 Subic Bay, 

Philippines

2 hr Flight control malfunction 

during approach

Although delayed event notifications and delayed deactivation of CVRs following safety 

events remain an ongoing problem, there is a limit to the efficacy and reliability of procedures to 

preserve these data because they are predicated on timely human action. The required use of 

extended duration CVRs on all aircraft currently required to be equipped with a CVR would better 

accommodate the variances resulting from the current procedural protections to safeguard these 

data by providing another layer of protection (additional recording time), particularly in cases 

where a crew does not deactivate the CVR in a timely manner after the event.

The NTSB has also conducted investigations of safety events for which CVR data were 

overwritten because of continued operation of the flight beyond 2 hours after the event. A 

particularly notable case was the October 21, 2009, incident involving Northwest Airlines

flight 188. The flight crewmembers did not communicate with air traffic control (ATC) for about

1 hour 17 minutes, during which time they overflew the intended destination at a cruise altitude of 

37,000 ft.6 The flight eventually landed without further incident after radio communication was 

reestablished. The event information on the airplane’s Honeywell solid-state 30-minute CVR was 

overwritten by the remaining 2 hours and 11 minutes of the 4-hour flight; the duration of the 

remaining flight time means that the result would have been the same if the aircraft had been 

equipped with a 2-hour CVR. Both pilots later reported that neither had fallen asleep during the 

flight and that “cockpit distractions” led to the event. Without a CVR recording covering the period 

the flight crewmembers weren’t in communication with ATC and overflew the intended 

destination, the NTSB was not able to determine the nature of the distraction, the sequence of 

events leading to the distraction, why the distraction lasted for such a long period of time, and 

appropriate procedures and actions to mitigate the safety risk. 

 6 For more information about this incident, see NTSB case number DCA10IA001.
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In 2017, about 56% of US block times consisted of long and medium haul flights with 

durations longer than 2 hours, including some international flights lasting over 12 hours.7

Therefore, in some cases, it may take longer than 2 hours to safely land and secure the airplane 

following an in-flight incident, and overwriting some of or all the pertinent audio is unavoidable. 

The NTSB also investigates many cases involving aircraft encounters with en route weather for 

which the CVR is sometimes not even requested due to the amount of time between the event and 

the completion of the flight. For in-flight weather events, CVR information can provide insight 

into flight crewmembers’ understanding of impending weather, including verbal descriptions of 

what they see on radar or outside the aircraft; weather sources and whether they were used; how 

weather information was used to make in-flight decisions; flight crew coordination with the cabin 

crew before the encounter; and the effect of the encounter on workload/cockpit task management.8

Table 2 lists incidents and accidents since 2002, including in-flight encounters with 

en route weather, in which the CVR was overwritten by continued operation of the flight beyond 

2 hours after the event. In situations such as these, an extended duration CVR would have the 

capacity to capture information during the remainder of the flight, a return to the airport (or 

diversion), landing, and taxi to the gate before relevant audio would be erased.

Table 2. Events for Which Pertinent CVR Data Were Overwritten During Remainder of Flight

Date Event 

type

NTSB # Location Length of 

CVR

Event Description

3/9/2017 Accident DCA17CA079 Dallas-Fort Worth 

(DFW), TX

Unknown 

(2 hr req)

En route Turbulence

10/2/2015 Incident ENG16IA001 Russian 

airspace/diversion 

to Tokyo, Japan

Unknown 

(2 hr req)

Engine failure

6/17/2012 Incident DCA12IA096 Las Vegas, NV Unknown 

(2 hr req)

Loss of 2 of 3 hydraulic 

systems

7/29/2011 Accident DCA11FA091 Tangshan, China Unknown En route Turbulence

1/3/2011 Accident DCA11FA050 Los Angeles, CA Unknown Tail strike upon takeoff

10/21/2009 Incident DCA10IA001 Minneapolis, MN 30 min Overflight of intended landing 

airport

6/23/2009 Incident DCA09IA064 Kagoshima, Japan Unknown Flight deck anomalies

11/26/2008 Incident DCA09IA014 Bozeman, MT Unknown Uncommanded thrust 

reduction

12/25/2007 Accident SEA08LA051 Honolulu, HI Unknown En route Turbulence

2/23/2007 Accident CHI07LA078 Chicago, IL Unknown En route Turbulence

9/16/2006 Accident NYC06LA223 Hastings, NE Unknown En route Turbulence

3/15/2006 Accident CHI06LA099 Omaha, NE Unknown En route Turbulence

10/22/2005 Accident NYC06LA016 Atlantic Ocean Unknown En route Turbulence

7/25/2004 Accident DCA04MA061 Miami, FL Unknown En route Turbulence

6/4/2004 Accident CHI04LA148 Liberal, KS Unknown En route Turbulence

4/21/2003 Accident CHI03LA113 Lithonia, GA Unknown En route Turbulence

4/22/2002 Accident NYC02LA088 Atlantic Ocean Unknown En route Turbulence

 7 ICAO defines block time as the time encompassing “the moment the aircraft is pushed back from the gate or 

starts taxiing from its parking stand for take-off to the moment it comes to a final stop at a gate or parking stand after 

landing.” Block time data obtained from http://web.mit.edu/airlinedata/www/Aircraft&Related.html.

8 For example, for a 2007 in-flight weather event in which two flight attendants and one passenger received 

injuries (NTSB case number MIA07LA086), CVR information showed that the captain had both provided verbal 

warning of potential turbulence and had activated the fasten seatbelt sign well in advance of the turbulence event. 
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Summary

The NTSB concludes that despite current FAA regulations to require 2-hour CVR 

recording capability and guidance intended to operationally safeguard CVR data after an accident

or incident, valuable CVR data continue to be overwritten and are unavailable for safety 

investigations. Therefore, the NTSB recommends that the FAA require that all newly 

manufactured airplanes that must have a CVR be fitted with a CVR capable of recording the last 

25 hours of audio. The NTSB also recommends that the FAA require retrofit, by January 1, 2024,

of all CVRs on all airplanes required to carry both a CVR and a flight data recorder with a CVR 

capable of recording the last 25 hours of audio. We recognize that the scope of these 

recommendations exceeds ICAO’s standard (which applies only to airplanes that weigh more than 

27,000 kg engaged in commercial transport), but the risk of lost CVR data is equal in accidents 

and incidents involving airplanes with a maximum takeoff weight under 27,000 kg, which include 

many regional airplane models.

Therefore, the National Transportation Safety Board recommends that the Federal Aviation 

Administration: 

Require all newly manufactured airplanes that must have a cockpit voice 

recorder (CVR) be fitted with a CVR capable of recording the last 25 hours of 

audio. (A-18-30)

By January 1, 2024, require retrofit of all cockpit voice recorders (CVR) on all 

airplanes required to carry both a CVR and a flight data recorder with a CVR 

capable of recording the last 25 hours of audio. (A-18-31)

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: October 2, 2018