AAIB investigation to BAE Systems (Operations) Ltd ATP, SE-MHF
Autopilot difficult to disconnect, on approach to East Midlands Airport, 14 December 2017.
Summary:
The aircraft was conducting an ILS approach to Runway 27 at East Midlands Airport (EMA). At around 800 ft agl (approximately 670 ft aal) the co-pilot attempted to disconnect the autopilot but it did not appear to disconnect. The crew made several further attempts to disconnect the autopilot before initiating a go-around at 230 ft aal. An uneventful, manually flown, circuit and landing was completed afterwards.
Although the crew perceived that the autopilot disconnected while the aircraft was climbing during the go-around, recorded flight data indicated that it disconnected at approximately 425 ft aal during the approach.
No defects or abnormalities were identified with any units associated with the autopilot.
Following this incident (and two earlier similar events), the manufacturer decided to review the Emergency Checklist to see whether it should be amended to address the condition where crews are unable to disengage an autopilot.
Bulletin correction
Prior to publication information was received from the aircraft manufacturer resulting in a correction being made to the report.
The amended report and full details of the correction can be viewed below.
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