Analysis of the Air India Express Boeing 737-800 accident at Mangalore last May has shown that, despite the long landing, the jet could still have stopped within the remaining runway distance.
The runway was dry and winds were calm, and the aircraft's auto-brake was only armed at a moderate setting when it flew over the runway 24 threshold at 200ft, travelling at 160kt - 16kt higher than its target speed.
This high-speed approach had already triggered the 737's load relief system to retract the landing flaps from 40° to 30°, to prevent damage. As the aircraft slowed below 158kt, the system redeployed the flaps to 40°, contributing to a prolonged float as the aircraft flared for touchdown. It landed two-thirds of the way down the 8,033ft runway.
In its inquiry report the Indian civil aviation ministry cites a Boeing test pilot's evidence that, had the captain deployed détente reverse thrust and applied maximum manual braking at touchdown, the aircraft could have stopped 7,600ft beyond the runway 24 threshold - within the paved area.
"While such stoppage figures are demonstrable during controlled test flying scenarios, these cannot be considered for landings during routine line operations," it concedes, although it adds that, in theory, the accident "might have been averted".
But the captain exacerbated the crisis, it says, making the "grave mistake" of trying to abort the landing, within 6s of applying brakes, even though he had already activated reverse thrust. The ministry says Boeing standard procedures "categorically state" that reverse thrust should not be cancelled in an attempt to go around.
Reconstruction of the conditions on a flight simulator demonstrated that, with proper descent planning and use of the autopilot, the aircraft "could have intercepted the correct ILS profile and made a successful landing".
Source: Air Transport Intelligence news
