India's Directorate General of Civil Aviation (DGCA) has issued its final report into a loss of separation incident between a British Airways Boeing 787-9 and a Thai Airways International 777-300 on 7 October 2017.
As the British Airways 787 (G-ZBKF), operating flight BA143 from London Heathrow to New Delhi, commenced its final approach to runway 29, the Thai 777 (HS-TKC) was lining up on the same runway for takeoff, operating flight TG316 to Bangkok Suvarnabhumi.
The report, which labels the incident serious, discovered that the relatively high speed of the 777 saw the mandated distance between arriving and departing aircraft breached – but air traffic control appears not to have noticed the evolving situation. As the Thai 777 commenced its takeoff roll, the BA 787 conducted a go around.
"This simultaneous going around of the BA143 and TG316 from runway 29 resulted in a breach of standard separation," says the report.
Lateral separation was reduced to less than 1nm (1.8km), while vertical separation was less than 200ft (60.9m). The incident occurred at 18:24 UTC, or nearly midnight local time. Weather was not found to be a contributory factor.
As a result of the incident, the DGCA made two recommendations to the Airports Authority of India. It called on the AAI to reemphasise situational awareness for tower controllers, specifying that non-standard language should be avoided.
It also suggested that the approach arrival controller "be made aware of inter-arrival spacing, speed control techniques, and use of standard language during inter-unit coordination."
The British Airways 787 was carrying 14 crew and 216 passengers, while the Thai 777 was carrying 24 crew and 234 passengers.