ASN Wikibase Occurrence # 364976
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| Date: | Wednesday 2 June 2010 |
| Time: | |
| Type: |  Airbus A318 |
| Owner/operator: | Air France |
| Registration: | F-GUGJ |
| MSN: | 2582 |
| Year of manufacture: | 2005 |
| Fatalities: | Fatalities: 0 / Occupants: |
| Aircraft damage: | None |
| Category: | Serious incident |
| Location: | OLRAK waypoint, Bordeaux FIR -
 France
|
| Phase: | En route |
| Nature: | Passenger - Scheduled |
| Departure airport: | Lyon Saint-Exupéry Airfield (LYS/LFLL) |
| Toulouse-Blagnac Airport (TLS/LFBO) | |
| Investigating agency: | BEA |
| Confidence Rating: |  Accident investigation report completed and information captured |
Air France flight AF850NE, an Airbus A318 and a Pilatus PC-12 (EC-ISH) were involved in an airprox incident in the Bordeaux FIR, France.
At 14:11, the pilot of the PC-12, en route from Buochs (Switzerland) bound for San Sebastian (Spain) contacted sector T of the en-route southwest ATC Centre at Bordeaux (CRNA/SO), stable at FL270. He was cleared on a heading for OLRAK.
At 14:15, the pilot of the PC-12 informed ATC that one of his altimeters was indicating FL 270 and the other FL 290. He asked the controller if the latter could help clear up this uncertainty by checking his altitude if he put the transponder on stand-by. The controller answered that he could not do that but that he was going to ask for information from the military ATC.
At 14:16, the controller contacted the military coordination and control centre (CMCC), call sign Marengo, also based in the CRNA/SO and asked them if there was a way to check the exact altitude of EC-ISH “other than by the use of secondary radar, with a primary radar for example“. Marengo answered that they only had a secondary radar image and that they would check it out.
At 14:17, the A318 crew contacted sector T of the CRNA/SO, in climb towards FL 230. The ATC answered that they would call back for a higher altitude. At 14:18, Marengo contacted the control and detection centre (CDC) at Lyon Mont Verdun and asked if they could read the altitude of a civil aircraft without an alticoder, in code 2742, east of Clermont (this related to the PC-12). The controller at of Lyon Mont Verdun CDC answered that he “reads FL 270 in mode C for this airplane“.
At 14:19:04, the A318 was cleared to climb to FL 290 on OLRAK. It was located behind the PC-12 on the same route. Its speed was about 170 kts more than that of the PC-12.
At 14:19:30, Marengo called back the controller at the CRNA/SO and relayed the information that indicated that the PC-12 was at FL 270.
At 14:19:48, the controller called PC-12 back to tell him that he was at exactly FL270 after a check via the military.
A 14:30:20, the pilot of the PC-12 informed the controller that an Air France airplane had passed very close to him and asked at what altitude this airplane was. The controller answered that this traffic was 2,000 feet above. The pilot answered that the traffic was just below and asked if the military were sure of the altitude that they had supplied.
At 14:31, the pilot of the A318 stated that he wanted to file an airprox as he had just overtaken an airplane at the same level while making an avoidance manoeuvre to the left. He stated that he had had no TCAS information.
The pilot of the PC 12 asked to descend to a level where he would be separated from all traffic. He stated that he had a problem with his 2 altimeters, which showed a variation of 2,000 feet and that the altitude displayed on the ATC control screens was apparently false.
There was no triggering of the Short Term Conflict Alert (STCA) system at the control position or a TCAS alert on either of the 2 airplanes.
The minimum separation between the 2 airplanes could not be measured on the recording, the 2 radar plots being mixed together. The crews estimated that the separation was between 15 and 30 metres horizontally and about 100 feet vertically.
CONCLUSION:
This incident was due to a leak at level of the static pressure line supplying the left side barometric and speed unit. This leak caused erroneous altitude and speed information to be supplied and led the PC 12 to fly at a level that was in conflict with flight AF 850 NE, without the risk of collision between the 2 airplanes being detected either by the ATC, or by the anti-collision systems such as the STCA or the TCAS.
The flight level displayed on the ground systems did not make it possible to dispel the doubt and thus led all of those involved (crew and controllers) to believe a flight level for the airplane that was erroneous. Due to this, the crew did not search any further for the causes of the inconsistency in the speed observed on the left side unit.
Accident investigation:
 |
|
Sources:
https://bea.aero/en/investigation-reports/notified-events/detail/incident-to-the-airbus-a318-registered-f-gugj-operated-by-air-france-and-the-pilatus-pc-12-registered-ec-ish-on-02-06-2010-near-bordeaux/
Location
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 19-Mar-2024 20:52 | ASN | Added |
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