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B738, vicinity Memmingen Germany, 2012

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Summary
On 23 September 2012 a Ryanair Boeing 737-800 made a premature descent to 450 feet agl in day VMC whilst turning right onto visual finals for runway 24 at Memmingen after the FMS selected altitude had been set to a figure only 44 feet above runway threshold elevation of 2052 feet amsl. EGPWS Alerts of ‘Sink Rate’ and ‘Caution Terrain’ prompted initiation of a go around which, as it was initiated, was accompanied by a an EGPWS ‘TERRAIN PULL UP’ warning. The go around and a second successful approach to runway 24 were uneventful. The Investigation is not yet complete.
Event Details
When September 2012
Actual or Potential
Event Type
Controlled Flight Into Terrain (CFIT), Human Factors
Day/Night Day
Flight Conditions VMC
Flight Details
Aircraft BOEING 737-800
Operator Ryanair
Domicile Ireland
Type of Flight Public Transport (Passenger)
Origin Manchester International Airport
Actual Destination Memmingen Airport
Take off Commenced Yes
Flight Airborne Yes
Flight Completed Yes
Flight Phase Descent
ENR / APR
Location - Airport
Airport vicinity Memmingen Airport
General
Tag(s) Approach not stabilised
CFIT
Tag(s) Into terrain,
Vertical navigation error
HF
Tag(s) Manual Handling
Outcome
Damage or injury No
Investigation Type
Type Independent

Description

On 23 September 2012, a Boeing 737-800 being operated by Ryanair on a scheduled passenger flight from Manchester to Memmingen commenced a day visual approach to runway 24 at Memmingen but as the aircraft turned right to regain the extended runway centreline at a continued high rate of descent, a series of Terrain Avoidance and Warning System (TAWS) alerts warnings triggered by terrain proximity occurred and a go around was flown to a subsequently uneventful second approach to the same runway followed by a normal landing.

Investigation

An Investigation was commenced by the Bundesstelle für Flugunfalluntersuchung (Germany) (BFU). QAR data was made available but the relevant Cockpit Voice Recorder (CVR) record was not. It was noted that the aircraft commander had been designated as [PF] for the incident flight and that both pilots were experienced on aircraft type in proportion to rank. It appeared that both had gained all their jet transport operating experience on the type being flown.

It was noted that whilst with Munich Radar during descent from the north, the flight crew had confused the clearance for a procedural Instrument Landing System (ILS) approach to runway24 at Memmingen with clearance for a visual approach as well as demonstrating a tendency to non standard R/T phraseology. However the visual clearance was subsequently approved and frequency change to Memmingen TWR was completed as the aircraft passed approximately 5400 feet QNH.

The aircraft rate of descent remained high and a speed of 250 KCAS was maintained until shortly before a very short base leg and turn onto final was attempted at 220 KCAS with the speedbrake out and a rate of descent of around 3000 fpm. Soon after the aircraft passed south of the extended centreline, still at high speed, the EGPWS ‘Sink Rate’ Alert had been activated and as the speedbrake was stowed and the AP disconnected, an EGPWS ‘Caution Terrain’ was activated. At this point, the aircraft was at 480 ft agl and the rate of descent had been arrested to about 500fpm, although the airspeed was still 210 KCAS. As a turn to regain the centreline was continued, an EGPWS Hard Warning ‘TERRAIN, TERRAIN, PULL UP, PULL UP’ quickly followed with the aircraft approximately on the centreline at 3nm from the threshold. A go around had been commenced from 460 feet agl with the vertical speed already around +600 fpm and the rest of the flight was uneventful.

The Investigation noted that the QNH at the time was 1012 hPa and that the elevation of the aerodrome was 2079 feet amsl. It was also found that the FMS selected altitude during the descent which led to the close ground proximity had been 2096 feet.

An Interim Report BFU EX002-12 on the Investigation with factual content only was published in December 2012. The Investigation is continuing.


Further Reading