Investigators of a serious “operational error” last year said in their recently released report that air traffic controllers at the Yangon International Airport allowed a crowded passenger plane to land on a runway that was already occupied by another aircraft and then failed to report the incident until nearly two weeks later.
The incident occurred on Dec. 18, 2017, when a trainee air traffic controller cleared a Bangkok-bound Thai Smile Airlines Airbus A320 to line up and wait in position for takeoff on runway 21 just as a Mann Yadanarpone Airlines ATR-72-600 from Sittwe was in its final landing approach, heading toward the same runway.
The A320 had 51 passengers and six crew members on board, while the ATR had 71 passengers and four crew members.
Two minutes the initial instruction, after the A320 was already in position, the trainee controller gave its crew a conflicting instruction, telling them to “line up and wait behind” the entrance to the runway until the ATR had landed. The crew responded that they were already on the runway.
According to the report published by Myanmar’s Aircraft Accident Investigation Bureau (AAIBM) on Monday, the trainee had forgotten that she had already cleared the A320 to line up on the runway.
Within the next 20 seconds, the A320’s crew contacted the air traffic control tower three times to inform them that they were occupying the runway, but they received no immediate response. The trainee controller later told investigators that she “did not know what to do.” Furthermore, her supervisor “went to the coffee bar to make coffee” a few minutes prior and did not hear the trainee’s mix-up.
Nearly 15 seconds after the third call from the A320, another trainee controller – who was only on his sixth day on the job – cleared the A320 for take-off and told the ATR to continue its approach.
According to radar evidence, the ATR crossed the runway threshold before the A320 had cleared the runway.
Though the second trainee’s decision averted a collision, it violated standard operating procedures, which dictate that he should have cancelled the A320’s takeoff clearance, instructed the ATR to execute a go-around or missed approach, and informed the pilot of the ATR about the obstruction so that he could have exercised judgement as a last resort.
In addition to these lapses, the controllers also did not report the incident to AAIBM until 11 days later, on Dec. 29.
In response to the error, AAIBM ordered all three controllers to take a series of three courses on aerodrome traffic control, safety, and reporting.