The UK Air Accidents Investigation Branch (AAIB) has released its report into an approach incident London Stansted Airport on 4 December 2023.
The serious incident under review saw a Ryanair Boeing 737 MAX 8 descend below minimum altitude (a ‘level bust’) during a go around procedure following an unstabilised approach.
The aircraft had entered an uncommanded nose down attitude at around 4000 feet, after the pilots commenced a go around whilst on approach to land, they regained control at around 1700 feet and landed safely.
Incident Overview
The aircraft was operating a scheduled flight from London Stansted Airport to Klagenfurt Airport, Austria, with a subsequent return to London Stansted.
The aircraft involved was a Boeing 737-8 MAX, registered EI-HET. Is a five-year-old narrow body aircraft belonging to the carrier Ryanair.
The outbound leg to Klagenfurt was performed without incident. On their return to London Stansted, flight crew planned to conduct a radar vectored CAT I ILS approach to Runway 22.
After an unstable ILS approach, the flight crew initiated a manually flown go-around at an altitude of 1,940 feet above mean sea level (AMSL) and 3.6 nautical miles from touchdown.
A critical oversight occurred during the go-around procedure at London Stansted. The Mode Control Panel (MCP) altitude display should have been set to the Missed Approach Altitude (MAA) of 3,000 feet AMSL. Instead it had remained set at 100 feet.
This oversight led to a level bust as the aircraft climbed through the MAA, prompting the pilot flying to pitch the aircraft nose down to initiate a descent.
During this descent, the aircraft reached a nose-down attitude of 17.7 degrees and an airspeed of 295 knots with flaps 5 extended. The Enhanced Ground Proximity Warning System (EGPWS) activated as the aircraft approached its lowest recorded altitude of 1,740 feet above ground level (AGL) before the pilot initiated a recovery maneuver.
Contributing Factors
The AAIB investigation identified several factors that contributed to the incident:
Failure to Set MAA: The flight crew’s oversight in not setting the MAA on the MCP prior to the go-around was a primary factor. This oversight was likely due to their focus on intercepting the glideslope from above, which required setting the MCP altitude below the aircraft’s current altitude.
Fixation on Flight Directors: The pilot flying’s fixation on the flight directors during the go-around prevented them from recognizing the need to level off at the MAA.
Excessive Nose-Down Attitude: The pilot’s response to the level bust, which involved moving the thrust levers to idle, resulted in an excessive nose-down attitude, rate of descent, and airspeed for the aircraft’s configuration.
Safety Actions
In response to this serious incident, the aircraft operator has implemented several safety actions, including:
- Informing pilots about the event and its contributing factors.
- Introducing a Discontinued Approach procedure to provide clear guidance to pilots in similar situations.
Lessons Learned
This incident underscores the importance of adhering to standard operating procedures, maintaining situational awareness, and avoiding fixation on flight instruments.
It highlights the potential dangers of failing to set the MAA and the need for pilots to be vigilant during go-around maneuvers, especially in instrument meteorological conditions.
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