Serious incident Boeing 737-8K5 (WL) G-FDZF, Saturday 11 September 2021 (2024)

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Date:	Saturday 11 September 2021
Time:	12:40 UTC
Type:	Boeing 737-8K5 (WL)
Owner/operator:	TUI Airways
Registration:	G-FDZF
MSN:	35138/2499
Year of manufacture:	2008
Engine model:	CFM56-7B27/3
Fatalities:	Fatalities: 0 / Occupants: 73
Other fatalities:	0
Aircraft damage:	None
Category:	Serious incident
Location:	Aberdeen International Airport (ABZ/EGPD) - United Kingdom
Phase:	Approach
Nature:	Passenger - Scheduled
Departure airport:	Palma de Mallorca Airport (PMI/LEPA)
Destination airport:	Aberdeen International Airport (ABZ/EGPD)
Investigating agency:	AAIB
Confidence Rating:	Accident investigation report completed and information captured

Narrative:
TUI Airways flight BY1665, a Boeing 737-800 (G-FDZF), suffered a deviation from the expected flightpath during a go-around at Aberdeen Airport.

The crew of G-FDZF had operated a passenger flight from Newcastle International Airport to Palma de Majorca Airport before operating the incident flight from Palma to Aberdeen Airport. The aircraft departed Palma at 10:47 UTC with 67 passengers and 6 crew on board. At 12:30 the flight crew established contact with Aberdeen Radar for a radar vectored CAT I ILS approach to Runway 34 at Aberdeen. At 12:35, as the aircraft was descending through 5,100 ft amsl, the crew were informed by ATC that there was a possibility that they may have to discontinue the approach, in which case they should
expect a climb straight ahead to 3,000 ft amsl. This was because a search and rescue helicopter, which was currently on the ground at the airport, would take priority once airborne.

The crew established the aircraft on the localiser and glideslope at 3,000 ft amsl with the aircraft configured with the landing gear down and flap 15. A single autopilot was engaged, as was the autothrottle. At 2,600 ft amsl the aircraft was instructed by the radar controller to break off the approach, climb to 3,000 ft amsl and turn left onto a heading of 270°. Twelve seconds later the autopilot was disengaged and the autothrottle, which remained engaged, increased engine thrust to 97% N1. After another six seconds, at 2,250 ft amsl, the aircraft began to climb towards the cleared altitude and started a left turn towards the assigned heading. As the aircraft, which was being manually flown, approached 3,000 ft amsl, it began to descend. Further heading instructions were passed by ATC whilst the aircraft descended, with it reaching a minimum altitude of 1,780 ft, corresponding to 1,565 ft agl, before a climb was re-established. The descent rate peaked at 3,100 ft/min as the aircraft passed 2,160 ft amsl.
The tower controller noted on the radar repeater in the visual control room that the aircraft was descending unexpectedly and contacted the radar controller to advise him. This prompted the radar controller to contact the crew, instructing them to climb to 3,000 ft amsl.
This call came just as the crew began to pitch the aircraft back into a climb. During the recovery the aircraft speed reached 286 KIAS, whereas the speed the crew had selected was 200 KIAS. As the aircraft passed through 3,000 ft amsl the crew re-engaged the autopilot and the flight path stabilised. The entire event occurred with the aircraft in IMC.
The aircraft was then given a further climb, before being radar vectored for another approach to Runway 34 where it landed without further incident.

AAIB Conclusion
The crew of G-FDZF were instructed to go-around by ATC. After initially climbing towards the miss approach altitude, the aircraft began to descend. The descent continued for 57 seconds reaching a minimum of 1,565 ft agl before the aircraft was recovered to a climb.
A combination of an unexpected large increase in thrust when the go-around was initiated, instructions from ATC to fly a heading, a lack of manual pitch trimming, and the changes in the flap configuration, caused the crew to become overloaded, allowing the aircraft to descend unnoticed for a significant period. Both pilots had experienced significant periods away from flying the aircraft type during the pandemic.

Accident investigation:

Investigatingagency: AAIB Reportnumber: AAIB-27673 Status: Investigation completed Duration: 11 months Download report: Final report

Sources:

1. AAIB Final Report: https://assets.publishing.service.gov.uk/media/62e9040a8fa8f503312d7d06/Boeing_737-8K5_G-FDZF_09-22.pdf
2. AAIB Bulletin S2/2021: https://assets.publishing.service.gov.uk/media/61a73d1e8fa8f5038358c0d8/S2-2021_Boeing_737-8K5_G-FDZF.pdf
3. https://www.scotsman.com/news/transport/boeing-plane-to-aberdeen-airport-involved-in-serious-incident-after-plummeting-with-67-passengers-on-board-3479722
4. https://news.sky.com/story/plane-made-rapid-descent-because-pilots-grounded-during-pandemic-investigators-say-12484525
5. https://news.stv.tv/north/pilot-that-deviated-from-flight-path-had-not-flown-in-18-months?top
6. https://www.balpa.org/Media-Centre/Press-Releases/BALPA-response-to-AAIB-report-in-to-an-incident-on
7. https://www.flightglobal.com/safety/pilots-lack-of-flying-explored-after-serious-737-go-around-incident-at-aberdeen/146694.article
8. https://en.wikipedia.org/wiki/Aberdeen_Airport

Images:

Figure: AAIB

Media:

During a go-around at Aberdeen Airport in September 2021, a Boeing 737-8K5 (G-FDZF) started to descend suddenly after climbing towards the target altitude before subsequently climbing.

Read the report: https://t.co/MBr5SfoKGh#AviationSafety pic.twitter.com/BYWsbg5viJ

— AAIB (@aaibgovuk) August 18, 2022

Revision history: