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| Date: | Friday 26 February 1999 |
| Time: | c. 08:30 LT |
| Type: |  Gulfstream G-IV |
| Owner/operator: | MBNA Corporation |
| Registration: | N85M |
| MSN: | 1023 |
| Fatalities: | Fatalities: 0 / Occupants: 6 |
| Other fatalities: | 0 |
| Aircraft damage: | None |
| Location: | near Lambourne VOR -
 United Kingdom
|
| Phase: | En route |
| Nature: | Executive |
| Departure airport: | Istanbul-Atatürk Airport (ISL/LTBA) |
| Farnborough Airport (FAB/EGLF) | |
| Investigating agency: | AAIB |
| Confidence Rating: |  Accident investigation report completed and information captured |
This incident involved a loss of separation, in Class A controlled airspace IMC, between a Boeing 737-300 (B737, D-ABEK) and a Gulfstream IV (GIV, N77SW). The B737 was inbound to London Heathrow Airport from Munich and the GIV was inbound to Farnborough Airport from Istanbul. The two aircraft were under the control of different controllers The loss of separation generated an ACC Short Term Conflict Alert (STCA) and both aircraft received Traffic Alert and Collision Avoidance System (TCAS) Resolution Advisories (RA). Separation was regained after a TCAS manoeuvre by the B737 and a change of heading by the GIV.
The GIV commander first contacted the Lambourne Sector Controller (LAM SC) at 0824 hrs and reported "FLIGHT LEVEL 150, HEADING 270". The call was acknowledged and he was asked to fly a heading of 275° with which the co-pilot, who was the handling pilot, complied. The next contact with the GIV from LAM SC was made at 0828 hrs clearing the aircraft for descent to FL120. The GIV commenced descent at 2,000 feet/min and maintained an airspeed of 300 kt.
The B737, also with the co-pilot handling, contacted the Heathrow Intermediate North Director (LL INT N) at 0822 hrs and reported approaching the Lambourne hold levelling at FL120. At 0823 hrs LL INT N instructed the B737 to descend to FL110 in the hold. This instruction received no response but when it was repeated the pilot said "WOULD APPRECIATE TO MAINTAIN FL120 AS LONG AS POSSIBLE TO STAY CLEAR OF CLOUD". The request was approved and the B737 remained in the hold at FL120.
At 0830 hrs the B737 was turning outbound in the hold onto an easterly heading when the commander reported that he had TCAS traffic at one o'clock descending. The LL INT N controller responded immediately by giving an avoiding action descent to FL110. The B737 then transmitted again saying that he was executing a TCAS manoeuvre, climbing to FL125. At 0831 hrs the B737 was re-cleared by LL INT N for descent to FL120 after having been informed that he was now clear of traffic.
At 0830 hrs the LAM SC and the GIV commander transmitted almost simultaneously but the last part of a transmission from the GIV was heard saying that he had a "TRAFFIC WARNING" ahead.
The LAM SC gave the aircraft an "IMMEDIATE LEFT TURN" to a heading of 180°. He then repeated this instruction including the phrase "AVOIDING ACTION". The GIV commander replied that they were already in the left turn and climbing. Half a minute later the GIV reported that they were clear of the traffic and maintaining FL116. The GIV was subsequently cleared for a right turn to a heading of 240° and for a climb back to FL120.
Accident investigation:
 |
|
Sources:
https://assets.publishing.service.gov.uk/media/5422f5a8e5274a13170005b5/dft_avsafety_pdf_502222.pdf
https://www.jetphotos.com/photo/222590 (Photo)
History of this aircraft
Other occurrences involving this aircraft
| 30 June 2023 | N924MB | Evolution Development Partners LLC | 0 | Andrews-Western Carolina Regional Airport (KRHP), NC |  |
non |
| Runway excursion | ||||||
Location
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 05-Oct-2025 12:47 | Justanormalperson | Added |
| 05-Oct-2025 12:48 | Justanormalperson | Updated [Accident report, ] |
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