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The southbound aircraft, BA 11, was cruising at FL330. The northbound aircraft, MH 24, had been cleared to climb to and cruise at Flight Level(FL) 350, with a requirement to reach the assigned level by 1801 hours local. Shortly afterwards BA 11 requested a diversion to the right of track. The aircraft was cleared to divert up to 90 kilometres to the right of track. The tracks flown by the aircraft were laterally separated by approximately 80 kilometres. About five minutes after being given approval to divert from his cleared track, the pilot of BA 11 requested a clearance to climb to FL 350. This request was denied by the Perth controller and the aircraft was given approval to divert either to the left or right of track, as required. At 1811 hours local the Perth controller gave BA 11 a clearance to climb to FL 350, at 1816 hours local. The aircraft acknowledged the clearance and during the subsequent climb advised sighting another aircraft, MH 24, an estimated two kilometres to the right and 1400 feet above his level. The investigation determined that the Perth controller had mistaken the time MH 24 had been required to reach FL350, 1801 hours, for the time he had calculated that the aircraft would pass. He had thus applied the required separation standard to this time instead of the calculated time of passing of 1818 hours local.

Download Final Report
[ Download PDF: 22KB]
 
 
 
 
General details
Date: 14 May 1987 Investigation status: Completed 
Time: 1818 Investigation type: Occurrence Investigation 
Location:450km North-west of Learmonth Occurrence type:Loss of separation 
State: Western Australia Occurrence class: Airspace 
Release date: 23 June 1987 Occurrence category: Incident 
Report status: Final Highest injury level: None 
 
Aircraft 1 details
Aircraft manufacturer: The Boeing Company 
Aircraft model: 747 
Aircraft registration: G-AWNO 
Type of operation: Air Transport High Capacity 
Damage to aircraft: Nil 
Departure point:Singapore
Departure time:N/A
Destination:Perth WA
Aircraft 2 details
Aircraft manufacturer: McDonnell Douglas Corp. 
Aircraft model: DC-10 
Aircraft registration: 9M-MAT 
Type of operation: Air Transport High Capacity 
Damage to aircraft: Nil 
Departure point:Perth WA
Destination:Kuala Lumpur, Malaysia
 
 
 
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