An airmiss incident between British Airways L1011 and Bulgarian T-154
On 6 February 1988, a British airways flight number BA305 Tri-Star L1011 was reroute from Paris De Gaulle airport to London Heathrow was decent and approach from Lydd radio navigation beacon. In the same time, another Bulgarian airline flight number LAZ967 a Tupolev 154 was left the holding path from navigation beacon reroute to London Gatwick airport. Both aircraft was cleared to descend to same flight level 180(18000 feet’s). The air miss happened when BA305 turn heading to Biggin Hill while LAZ967 heading to Eastwood. The pilot on Tristar BA305 saw the LAZ T154 aircraft, and made a violent right turn to avoid the collision. The main cause in this accident of “human error” between ATC(air traffic controller and air traffic controller, air traffic controller and pilot)
History of the Flight
At1000hours on 6 February 1988, both Gatwick airport and London Heathrow airport was temporary closed. The reason for Gatwick was close runway 26L for the runway light repair. At Heathrow airport, after the detection of runway surface damage on 27L, it also close for repair and only one runway in operation at 27R. The rare of close in both airport runway circumstances has largely increase the airflow at London Air Traffic Control Centre (LATCC) between 1100 and 1200hours local time, the air traffic was in a complex and unusual situation. Inbound aircraft for landing in Gatwick aiport was holding in Eastwood, for inbound aircraft to Heathrow was holding in Lydd and Biggin Hill.
The Bulgarian airlines LAZ967 a Tupolev aircraft was on at schedule service flight from Capital Sofia to London Gatwick, the aircraft entered London air traffic control zone at 1122 local time through waiway UG106 in Lydd/Dover sector. LAZ967 was cleared to descend from cruising attitude to FL280. The initial radiotelephony (RTF) was cleared the aircraft enroute via Lydd VOR to Eastwood and land in Gatwick. Lydd controller was guiding the aircraft holding in FL210 then decent to FL180. Due to the high traffic load, the air traffic controller on Lydd (frequency 127.1MHZ)relocate LAZ967 contact London controller at 132.45Mhz. at 1138hours, LAZ decent and maintain at FL180 and turn heading 270, during the turn in Biggin Hill, LAZ967 crossed very close in front of and slightly above the Britisih Airways Tristar(BAW305).
The BA305 was operate by British airway as schedule service from Paris to London Heathrow by a Tri-star airliner, at 1129 hours, BA305 through airway A20 entre London Air traffic Control centre(LATCC). The initial contact was on VHF frequency 127.1Mhz at Lydd, the sector controller guiding BAW 305 maintain FL240 enroute to Abbeville, Biggin Hill and intercepted and landing into Heathrow runway 27R. At 1136hours, Lydd Sctor controller cleared BA305 descend and maintain FL180 at Biggin Hill with heading 300 degree. At 1138 hours, the British Tri-Star BA305 pilot saw the Tupolev LAZ967 on his right, he immediately put the aircraft into a steep right hand descending turin and passed very close and above the LAZ967 aircraft.(Aircraft accident Report no 1/89)
In an unusual circumstances of both runway in repair in Heathrow and Gatwick had caused large traffic flow at London Air Traffic Control zone, at the period of high workload, there seems a big problem of co-ordination and cross checking between air traffic controller in London centre and Lydd sector controller, it has direct cause two traffic controller was controlling two different aircraft at the same airspace with different radio frequency such as London VOR132.45MHz and Lydd VOR(127.1Mhz).
Lack of ATC simulator training, at the time 1989, ATC was continuous “on the job” assessment of each Air Traffic Controller, and the condition of ATC licence renewal one relay on medical check as well as short oral examination, the controller can stay in the job for years without any training for air miss emergency situation, this may cause stress during the time of high traffic load.