ASN Wikibase Occurrence # 232061
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| Date: | Wednesday 1 January 2020 |
| Time: | 19:31 LT |
| Type: |  Airbus A350-941 |
| Owner/operator: | Thai Airways International |
| Registration: | HS-THF |
| MSN: | 123 |
| Year of manufacture: | 2017 |
| Engine model: | Rolls-Royce Trent XWB-84 |
| Fatalities: | Fatalities: 0 / Occupants: 324 |
| Aircraft damage: | None |
| Category: | Serious incident |
| Location: | Frankfurt International Airport (FRA/EDDF) -
 Germany
|
| Phase: | Approach |
| Nature: | Passenger - Scheduled |
| Departure airport: | Phuket International Airport (HKT/VTSP) |
| Frankfurt International Airport (FRA/EDDF) | |
| Investigating agency: | BFU |
| Confidence Rating: |  Accident investigation report completed and information captured |
Thai Airways International flight TG926, an Airbus A350-900, made an unstable approach to Frankfurt-Main Airport Germany, and descended below the glideslope before a go around was initiated.
The captain was Pilot Monitoring (PM) on this flight. The co-pilot was the Pilot Flying (PF). During the approach two other co-pilots were in the cockpit as observers.
Around 19:15 the aircraft flew with activated autopilot on the southern approach route of Frankfurt/Main Airport. They followed an aircraft flying ahead during the approach. According to his statement, the PM assumed to land on runway 07R after the aircraft in front. At 19:24:26, the radar approach controller, responsible for "pick-up", asked the crew whether it was correct that a sick passenger was on board. This was confirmed by the crew. The pilot also asked whether additional assistance was needed. The crew confirmed that they had already requested medical assistance for the passenger at the parking position. This was preceded by a message that the cockpit crew had sent to the air carrier's OPS centre via the on-board ACARS system approximately 4 hours before the planned landing in Frankfurt Main. This message contained the information to provide an ambulance for a passenger at the parking position.
At 19:27:22 the radar approach controller instructed the PM to switch to the radio frequency of the Radar controller. At 19:27:38 he instructed the cockpit crew to accelerate the descent. At 19:27:59, the controller issued the ATC instruction to steer the aircraft towards 340° and to descend to an altitude of 3000 ft AMSL. With a further vector, the controller instructed the cockpit crew to fly in the direction of 040° and at the same time gave clearance for instrument approach ILS 07R Z. In addition, the crew was instructed to fly at a speed of 170 kt IAS or faster. Analysis of the flight recorder data showed that the landing flaps were set to position 1 at about 19:28:48, at a flight altitude of about 6000 ft AMSL, and to position 2 about 18 seconds later. Shortly thereafter the landing gear was extended at an altitude of about 5100 ft AMSL. During this flight phase the sink rate was about 2000 ft/min. After the aircraft turned to the approach baseline for runway 07R and reached a flight level of about 4000 ft AMSL, the sink rate increased continuously. At 19:30:42 the aural altitude announcement Two Thousand Five Hundred sounded, and at the same time the autopilot was switched off. At about 19:30:55, at a flight altitude of about 1900 ft AMSL, the Autopilot Localizer Engaged mode was recorded on the flight data recorder. About 9 seconds later the two Sink Rate warnings sounded. Another 5 seconds the altitude "One Thousand" was announced and 2 seconds later by "Glideslope". At 19:31:16 the PF gave the command to go around and the PM reported this to the tower controller shortly after. This was the first radio contact of the crew with Frankfurt Tower. At this time the aircraft was in 668 ft AGL (204 m). The distance to runway threshold 07R was 6.43 NM (11,9 km). The second approach to runway 07R was performed with the help of the instrument landing system. The height above the event location (6.43 NM) now was 2238 ft AGL (682 m).
The subsequent landing on runway 07R at 19:45 was performed without further problems.
Causes
After a shortened final approach, the Airbus A350-941 was flying at night in good visual meteorological conditions unstabilized on instrument approach to runway 07R of Frankfurt/Main Airport. The glide slope of the instrument landing system was flown through from above. Starting at 3,300 ft AMSL, the flight path was continuously below the glisdesope. The cockpit crew aborted the instrument approach and initiated a go-around procedure about 6 NM ahead of the runway threshold 07R at 668 ft AGL, i.e. far below the glide slope.
The investigation determined:
- Errors in the programming of the waypoints in the flight management system
- Errors in the handling of the auto flight system for the approach
- Reduced situational awareness of the pilots in regard to the spatial position
- Communications and cooperation deficiencies within the flight crew.
Accident investigation:
 |
|
Sources:
https://www.bea.aero/en/investigation-reports/notified-events/detail/event/serious-incident-to-the-airbus-a350-registered-hs-thf-operated-by-thai-airways-on-01012020-at-fran/
https://flightaware.com/live/flight/HSTHF/history/20200101/0540Z/VTSP/EDDF
https://www.bfu-web.de/DE/Publikationen/Bulletins/2020/Bulletin2020-01.pdf?__blob=publicationFile
Images:
Figure: BFU
Figure: BFU
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 11-Jan-2020 20:44 | harro | Added |
| 11-Jan-2020 20:44 | harro | Updated [Departure airport, Photo] |
| 31-Mar-2020 18:50 | harro | Updated [Source, Narrative, Photo] |
| 31-Mar-2020 18:51 | harro | Updated [Photo] |
| 10-Aug-2022 12:36 | harro | Updated [Total occupants, Location, Narrative, Accident report] |
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