|Title:||Proximity conflict, Boeing 737-2D6, 7T-VEY, 21 December 1995|
|Micro summary:||A misinterpreted GPWS and automated tower warnings motivates ATC to command a just-departed DC-9 to maintain 500', expecting a landing airplane to do a go-around. It did not, and landed normally.|
|Event Time:||1995-12-21 at 1352 UTC|
|Publishing Agency:||Aircraft Accident Investigation Board (AAIB)|
|Publishing Country:||United Kingdom|
|Site of event:||London Gatwick Airport, West Sussex|
|Latitude/Longitude:||737: Landing; MD-87: Takeoff, Runway 08R|
|First Airplane||Second Airplane|
|Departure:||Oran, Algeria||Gatwick Airport, London, England|
|Destination:||Gatwick Airport, London, England||Madrid Barajas International Airport, Madrid, Spain|
|Airplane Type(s):||Boeing 737-2D6||McDonnell Douglas MD-87|
|Type of flight:||Charter||Revenue|
|Executive Summary:||The Boeing 737, registration 7T-VEY, was on a charter flight from Oran (Algeria) to London Gatwick. Approaching from the direction of SELSI reporting point, the aircraft was transferred to Gatwick Approach control at 1345 hrs. The controller advised that it had 30 nm to run for a straight in approach to Runway 08R and requested confirmation that the crew could lose the necessary height in that distance remaining. The reply was in the affirmative. Radar information indicated that the aircraft was passing FL100 at that time. The aircraft was cleared to descend to 4,000 feet on the QNH of 1006 mb and was requested to remain on its present heading until established on the localiser. |
At 1347 hrs, the preceding aircraft (also a Boeing 737, flight number BA2573) was becoming established on the localiser for 08R and advised ATC that in its current position the wind was 242° at 27 kt, stating that there was a 27 kt tailwind in the approach area. The aircraft was advised that the surface wind at Gatwick was from 070° at 5 kt. The controller passed the upper wind information to the Gatwick Aerodrome controller, but did not advise 7T-VEY specifically of this information.
At 1349 hrs, 7T-VEY was cleared to descend to 3,000 feet and to descend further with the glidepath. The crew reported that the aircraft was fully established on the ILS at 1350 hrs and was requested to transfer to the Gatwick Aerodrome controller and to advise him of the speed at that time (although no specific speed control had previously been requested by ATC). On transfer, the crew reported that the current speed was 200 knots. The Aerodrome controller requested the aircraft to reduce speed to 160 knots.
The Aerodrome controller had already cleared EC-FFA (departing on a scheduled flight to Madrid) to line upon Runway 08R after the landing Boeing 737 (BA2573) and to be ready for an immediate departure when cleared. The controller was aiming to get it airborne ahead of 7T-VEY landing. At 1351 hrs, 7TVEY was requested to reduce speed to minimum approach speed. When the aircraft was slowing through 180 knots,the controller instructed the aircraft to come back to minimum approach speed "as fast as you can please". Immediate take-off clearance was issued to EC-FFA, and 7T-VEY was advised to expect a late landing clearance.
At 1352 hrs, a GPWS "PULL UP" warning was transmitted over the radio. The controller assumed that 7T-VEY was about to initiate a go-around, as the aircraft also activated the alert on the Approach Monitor Aid (AMA) in the Tower. He requested EC-FFA to "stop immediately", but the crew responded that they were already airborne. The controller then instructed EC-FFA to "maintain five hundred feet", which was responded to by the crew. Five hundred feet indicated with QNH set on the aircraft's altimeters would have been about 300 feet above the local terrain level at the departure end of Runway 08R, significantly below the Minimum Safe Altitude in that area.
Shortly after this, the crew of 7T-VEY stated that they had the runway in sight and the aircraft was cleared to land, which it did uneventfully. Re clearance on the original Standard Instrument Departure was then issued to EC-FFA. Post-incident radar data analysis indicated that EC-FFA had initiated its climb while within 0.5 nm from the upwind end of Runway 08R.
|Learning Keywords:||Operations - Airspace - Air Traffic Control|
|Operations - Airspace - GPWS|
|Systems - Automation Design|
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