The incident occurred @ 05.05 hrs. The aircraft landed at EIDW 17 minutes later @ 05.22 hrs.
The minimum recording duration required by the FAA for aircraft manufactured after April 7, 2010 [which does not describe the aircraft in question] of a CVR is 2 hours (
14 CFR 91.609 (i) (2)).
2.11 Lack of CVR Data
The non-availability of the CVR denied the Investigation the opportunity to fully understand the cockpit environment at the time of the occurrence and to accurately account for the communications, discussions and actions of the Flight Crew as they responded to the unfolding events.
As stated in Section 1.9.2 of this report, the Investigation notes and accepts the Co-Pilot’s statement that he thought the circuit breaker for the CVR had been pulled. The Investigation reviewed the Operator’s published guidance on the use of Flight Recorders. The guidance material might lead Commanders to believe that data from CVRs is to be used for accident investigation only, and that only Company officials (other than Flight Crew) may preserve Flight Recorders and authorise their removal. This could be interpreted in a way that is not consistent with the requirements of ICAO Annex 6, Section 6.3.4.2.2, Operation of Flight Recorders, and specifically Section 11.6, preservation of Flight Recorder records (responsibility of the operator).
Therefore, the Investigation makes the following Safety Recommendation to the Operator.
Safety Recommendation No. 8
United Airlines should review its Operations Manual to ensure that the procedures associated with the preservation of Flight Recorders following an Accident or Incident are in accordance with the provisions of ICAO Annex 6 (IRLD2016-011).