Ryanair B38M at London on Dec 4th 2023, rapid descent during go around

Last Update: November 21, 2024 / 11:10:03 GMT/Zulu time

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Incident Facts

Date of incident
Dec 4, 2023

Classification
Incident

Airline
Ryanair

Flight number
FR-1269

Departure
Klagenfurt, Austria

Destination
London Stansted, United Kingdom

Aircraft Registration
EI-HET

Aircraft Type
Boeing 737-800MAX

ICAO Type Designator
B38M

Airport
London Stansted Airport, London

Airport ICAO Code
EGSS

A Ryanair Boeing 737-8 MAX, registration EI-HET performing flight FR-1269 from Klagenfurt (Austria) to London Stansted,EN (UK), was on final approach to Stansted's runway 22 descending through about 1900 feet MSL (1525 feet AGL) at about 145 knots over ground about 3.2 nm before the runway threshold at 11:03L (11:03Z) when the crew initiated a go around due to an unstabilized approach. The aircraft accelerated and climbed through about 4000 feet at 197 knots over ground when the aircraft began to rapidly descend to 2175 feet MSL (1825 feet AGL) within 17 seconds accelerating to 280 knots over ground, climbed and descended a second time reaching a minimum height of about 1700 feet AGL. The aircraft subsequently climbed to and stabilized at 3000 feet, positioned for another approach and landed without further incident about 12 minutes after the initiation of the go around.

The British AAIB reported they have opened an investigation stating: "High speed and high nose down pitch attitude during go-around, London Stansted."

The Irish AAIU, participating in the investigation, stated a level bust.

The airline reported an unstable approach before landing, they are cooperating with the AAIB.

On Nov 21st 2024 the AAIB released their final bulletin concluding the probable causes of the serious incident were:

This serious incident occurred because the Missed Approach Altitude (MAA) was not set in the Mode Control Panel (MCP) before a go-around was performed. It was not set to the MAA because the flight crew were attempting to intercept the glideslope from above. This required the MCP selected altitude to be set to a height below the aircraft, and the MCP selected altitude was not adjusted to the MAA following the decision to go-around before it was executed.

The approach and go-around were flown in instrument metrological conditions (IMC) and hence the pilots had no external visual references. During the go-around the pilot flying was fixated on the Flight Directors and did not recognise that they did not command a level off at the MAA until it had flown through it.

The subsequent recovery manoeuvre from the level bust was probably exacerbated by the thrust levers being moved from a high-power setting to idle resulting in an excessive nose-down attitude, rate of descent and IAS for the aircraft’s configuration. Given the aircraft’s height during this descent the Enhanced Ground Proximity Warning System was triggered just after the commander had initiated a pitch up into a climb back to the MAA.

This serious incident involved a Boeing 737-8200 [MAX]. It could have occurred in any variant of the Boeing 737, or any other type of aircraft with similar autopilot and flight director systems. There have been other serious incidents, with similarities to the EI-HET that have been investigated.

The AAIB analysed:

Initial approach

EI-HET was conducting a radar vectored CAT I ILS approach in IMC to Runway 22 at Stansted Airport, where its crew were based. As the aircraft was in IMC throughout this serious incident, there were no external visual cues with which to assist the crew in maintaining spatial orientation. They were thus reliant on the aircraft’s flight instruments.

The volume of air traffic in the area at the time was described as low, and there was no perceived pressure on the flight crew or the ATCO’s. Between approximately 20 and 15.5 nm from touchdown the aircraft was close to being on a 3° CDA. During this period, believing that the aircraft was a little high for a CDA, the ATCO gave the aircraft a heading adjustment to give it more track mileage to lose some height.

By the time the aircraft was established on the LOC at 9 nm, the aircraft was at 3,863 ft aal, about 1,000 ft above the G/S, with Flaps 10 selected and with the G/S indicator showing 3-dots below. Had more stages of flaps been deployed, and possibly the landing gear lowered, prior to the LOC being captured this would have increased the aircraft’s drag, and rate of descent, assisting it to capture the G/S.

At about 4 nm, and having recognised that they would be attempting to capture the G/S from above, the MCP altitude was incorrectly reset from their last descent clearance to 100 ft, about 10 seconds before the GA was initiated. It should have been set to 1,400 ft (1,000 ft AFE). Had it been reset earlier in the approach it would have offered the crew more time to notice the incorrectly set MCP altitude. This too would have avoided the aircraft entering ALT ACQ as it approached the last ATC cleared altitude of 2,000 ft amsl. This caused a distraction and a peak in the commander’s workload as he had to reset the MCP to a lower altitude and select LVL CHG to keep the aircraft descending. Given these multiple MCP selections it is possible that the commander set the MCP altitude in haste without checking it. Whilst the crew may have believed they could have captured the G/S within the limits specified in the operator’s OM, this was not achieved, and they correctly decided to conduct a GA. As the MCP altitude was still set to 100 ft, and not the MAA, the F/Ds would not have commanded a level off. Whist the operator’s Landing Procedure - ILS stated that the MAA should be set and checked at G/S interception, there was nothing explicit in the G/S from above technique to give the crew guidance on when to set the MAA. However, the operator commented that it was implicit given it is to be checked as part of the Landing Procedure.

At no point during the approach did either crew member share their mental model as to where they thought the aircraft was on the 3° CDA profile until the likelihood of a GA was mentioned by the commander at about 5 nm. It is essential that flight crew share their mental model throughout all phases of flight so that if there is a discrepancy this can be discussed in good time so prompt action can be taken to resolve the issue, before more positive action, like a GA, is required.

Missed Approach Procedure (MAP)

The initial part of the GA was correctly flown, despite the commander stating he was fixated on the F/Ds. This fixation was probably a result of the high workload experienced during the instrument approach, which subsequently increased, along with some startle factor, when the GA was initiated. Had the MAA been set correctly it is likely the commander would have followed the F/Ds and levelled the aircraft at the required altitude of 3,000 ft. However, with an MCP altitude below that of the aircraft, the F/D continued to command a climb until either an altitude above the aircraft was set or there was some manual flying intervention by the PF, with the latter being the case in this event. Once the crew recognised they had flown through the MAA they established a descent to correct the situation.

The GA was initiated at 3.6 nm and 1,940 ft amsl. Once the aircraft was in the climb, with GA power applied, there was little time to recognise the lack of guidance from the flight director to capture the altitude and level off at 3,000 ft without guidance from the F/Ds. However, as there was no urgency to commence the GA at this point, had the crew continued with the approach for about another 2 nm, it would have given them about 40 seconds to conduct a ‘mini-brief’ in which they could remind themselves of their actions in the GA and given them the opportunity to check the MAA was set correctly.

Whist the commander recognised he needed to lower the nose to descend, which he initially set between 5 and 10° nose-down, the subsequent nose-down attitude was probably a result of the push on the control column, a nose-down trim input and a pitch/power couple when the thrust levers were closed from a high-power setting to idle. At this time the MCP altitude was reset by the commander, initially to 5,600 ft, probably in haste, before being correctly set to the MAA of 3,000 ft. Had he requested the co-pilot to do this, as stated in the FCOM, he would have had more of his limited capacity available for his primary task of flying the aircraft.

During the descent the aircraft reached a maximum pitch of 17.7° nose-down, a descent rate of 8,880 fpm, and an airspeed of 295 KIAS with Flaps 5 extended; the lowest recorded height was 1,740 ft agl. The commander recognised the excessive nose-down attitude and initiated a recovery just before the EGPWS was triggered. Had he not initiated the recovery before the warning occurred, the EGPWS’s aural and visual warnings were a safety barrier that would have alerted the crew to the high rate of descent close to the ground, and this should have caused them to take appropriate recovery actions.

The co-pilot’s first call of “speed” was during the descent from 4,000 ft, when the aircraft was at about 235 KIAS and accelerating. This was about 40 kt greater than the OM requirement to call “speed” at 195 KIAS (VFLY +10). This delay in calling “speed” could be explained by the co-pilot experiencing some form of startle and surprise by the dynamic nature of the manoeuvre. His attention may also have been focused elsewhere in the cockpit before he recognised the situation.

The GA was initiated at 3.6 nm. Given there was no urgency to initiate it, the crew could have elected to continue with the approach until about 1 nm from touchdown, assuming the MCP altitude had been reset to the MAA. Given the aircraft was flying at about 180 kt, it gave the crew about 40 seconds in which to compose themselves and brief what actions they were each going to perform during the GA, including a check that the MAA was set correctly. Had it been set when the GA was initiated this serious incident probably would not have occurred.

There are three SIDs, from Runway 22, that route to the north of the airport, all with an initial climb clearance of 4,000 ft amsl. Had an aircraft departed close to the time EI-HET initiated the GA there was a possibility that the two aircraft may have come into conflict with each other.

Somatogravic illusion

The manufacturer’s study of this event suggested that there was potential for spatial disorientation during this GA. However, given that the commander was predominately fixated on the F/D during the GA and there was no significant pitch down input until after the level bust, it is more likely that the push on the control column was a response to the PF realising they had flown through their cleared altitude of 3,000 ft amsl, rather than any perceived visual illusion. Hence it is unlikely that the commander experienced spatial disorientation.

Metars:
EGSS 041320Z AUTO 11009KT 090V150 5000 BR OVC003 06/05 Q0996=
EGSS 041250Z AUTO 11010KT 090V150 7000 OVC003 06/05 Q0996=
EGSS 041220Z AUTO 11010KT 080V150 7000 OVC003 06/05 Q0996=
EGSS 041150Z AUTO 11009KT 090V150 3500 BR OVC003 06/05 Q0996=
EGSS 041120Z AUTO 11009KT 090V150 6000 -RA OVC003 05/05 Q0997=
EGSS 041050Z AUTO 12010KT 6000 -RA OVC004 05/05 Q0997=
EGSS 041020Z 13012KT 9999 OVC004 06/05 Q0997=
EGSS 040950Z 13012KT 9999 OVC004 05/05 Q0997=
EGSS 040920Z AUTO 13012KT 9999 OVC004 05/04 Q0997=
EGSS 040850Z AUTO 13011KT 110V170 9999 OVC003 05/05 Q0997=
Aircraft Registration Data
Registration mark
EI-HET
Country of Registration
Ireland
Date of Registration
Hdffhp kbkcqcpipp Subscribe to unlock
Manufacturer
THE BOEING COMPANY
Aircraft Model / Type
BOEING 737-8200
ICAO Aircraft Type
B38M
Year of Manufacture
Pbqc Subscribe to unlock
Serial Number
Ihhib Subscribe to unlock
Maximum Take off Mass (MTOM) [kg]
B pmf Subscribe to unlock
Engine Count
A Subscribe to unlock
Engine
Fkmdcknndmlk Subscribe to unlock
Main Owner
Alcmlpbcilmbqiihgm j jgnnebflpcqjmiq bgmbfnqgjA nmAkpjjnejekibbnb Subscribe to unlock
Incident Facts

Date of incident
Dec 4, 2023

Classification
Incident

Airline
Ryanair

Flight number
FR-1269

Departure
Klagenfurt, Austria

Destination
London Stansted, United Kingdom

Aircraft Registration
EI-HET

Aircraft Type
Boeing 737-800MAX

ICAO Type Designator
B38M

Airport
London Stansted Airport, London

Airport ICAO Code
EGSS

This article is published under license from Avherald.com. © of text by Avherald.com.
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