By: Stephen Leaper, Curtiss-Wright Defense Solutions
Today, in the U.S., cockpit voice recorders (CVR) used on commercial aircraft are only required to capture and store two hours of audio information. After two hours, the most recent information is lost when the CVR, due its limited storage capacity, records over the previous cockpit conversations. Frequently, information of interest is lost because it was recorded early in a multi-hour flight. By the time the aircraft lands, the CVR may have rewritten over the desired critical information multiple times. It’s clear that limiting CVR recording capacity to two hours is insufficient. Timely examples include the recent Alaska Airlines flight during which a fuselage plug was lost. Following the incident, the flight continued on to Portland, Oregon, and by the time a mechanic was able to pull the recorder, the communication had been overwritten. In the case of a dramatic runway incursion last year at New York’s John. F. Kennedy International Airport, the pilots took off for a multi-hour trip to London after nearly hitting another loaded passenger jet. Again, inter-plane ATC communication was overwritten during the flight, significantly hindering a vital element of the ensuing investigation.
Mandating the use of CVRs with 25-hour recording capacity is not a new idea. In fact, 25-hour CVRs have been required by the European Union Aviation Safety Agency (EASA), the FAA equivalent in Europe, since January 2021 for European aircraft. Technically speaking, the requirement is that all EASA-registered aircraft with a maximum certified takeoff mass (MCTOM) of over 27,000 kg should be capable of recording 25 hours of audio3. However, today, this mandate is only applied to aircraft produced from 2021 and is not retroactive.
Now, for the first time, it is beginning to look like some aircraft in the US may soon be required to install 25-hour CVRs. In December 2023, the FAA proposed requiring 25-hour CVRs for newly manufactured planes. Some leading experts are demanding more. For example, NTSB Chair, Jennifer Homendy, recently called for the FAA to modify its proposal so that all aircraft currently flying will be retrofitted with a more capable 25-hour CVR.
Helping to drive this new regulatory activity are a number of recent incidents during which a two-hour CVR failed to retain important information. In January 2024, for example, when Alaska Airlines flight 1282 suffered a decompression event, in the chaos of landing and evacuating the CVR continued to record so that all of the audio leading up to and including the event was lost.
Flight recorders have continued to evolve since they were first introduced in the 1950s to help accident investigators determine the reasons for accidents and, in turn, enable authorities to recommend changes to help mitigate future incidents. Over time, flight authorities have mandated that certain aircraft have a recorder with a minimum set of functions. As we learn from new incidents, additional regulations are introduced to expand that set of mandated functions after investigators discover that contemporary FRs didn’t capture enough critical and useful communications.
Today, 25-hour CVRs are readily available and are currently in use on EASA-regulated aircraft and beyond. Some US airlines aren’t waiting for the FAA to act but are instead already installing 25-hour CVRs on their aircraft fleet. An example of a 25-hour CVR is provided by the HCR-25 (Honeywell Connected Recorder 25 hrs), which was developed in partnership by Honeywell and Curtiss-Wright. The HCR-25 cockpit voice recorder supports four high-quality communications channels and a CPDLC datalink recording channel, each of which records for 25 hours. The unit is fully ED-112A compliant and is designed to be installed into existing aircraft equipment trays, offering a simple upgrade path from current 2-hour voice recorders.
References
1 Federal Aviation Administration (FAA), 2023, Federal Register : 25-Hour Cockpit Voice Recorder (CVR) Requirement, New Aircraft Production, online, available from https://www.federalregister.gov/documents/2023/12/04/2023-26144/25-hour-cockpit-voice-recorder-cvr-requirement-new-aircraft-production
2 Wallace G., 2024, Cockpit voice recorders only record 2 hours at a time. The NTSB chair wants it to be 25 hours, CNN US, January 8, 2024, online, available from https://edition.cnn.com/2024/01/08/us/ntsb-chair-calls-for-longer-memory-in-cockpit-voice-recorders/index.html
3 EASA, 2016, New regulation, new timings, On Air, Issue 9 - Flight Tracking, online, available from https://www.easa.europa.eu/newsroom-and-events/news/new-regulation-new-timings