Overwritten or Unrecorded: A Study of Accidents & Incidents in Which CVR Data Were not Available

Abstract

In recent years there have been numerous accidents and incidents for which investigators were unable to retrieve pertinent cockpit voice recorder (CVR) data. As a result the International Civil Aviation Organization and the European Union are introducing new requirements so that, from 2021, newly-manufactured transport aircraft over 27,000 kg must be equipped with 25-hour CVRs. This study examined 15 accidents and incidents that occurred between 2014 and 2017. Five reasons were identified for CVR data not being available for these events. The study indicates that in a majority of the events relevant data would have been retained if 25-hour CVRs had been used. In addition, the study highlights the lack of standardization in the presentation of CVR data in accident and incident reports. In order to facilitate a comprehensive assessment of the new CVR requirements, recommendations are made about the CVR metadata that should be included in future reports.

Appendices

Appendix 1: Information About the Safety Events

Table 2 below contains further information about the safety events in this study. The 15 events featured a total of 17 aircraft. Events #10 and #11 each involved two aircraft. Events #1-3 featured aircraft with an MCTOM of less than 27,000 kg, which is the threshold for the new 25-hour CVR requirements.

Table 2. Further information about the safety events.

Appendix 2: Results of the Study

Table 3 below summarizes the results of the study. The key for RQ1 is as follows:

Table 3. Summary of results.

• (A) remaining flight time after the safety event exceeded CVR recording duration;

• (B) CVR not promptly deactivated when the aircraft was on the ground after the safety event;

• (C) delay in notifying investigating agency about the safety event;

• (D) CVR deactivated before the safety event occurred;

• (E) no CVR on the aircraft.