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Landing mode changes snared 777 go-around pilots

German investigators’ findings from the Singapore Airlines Boeing 777-300ER excursion at Munich, showing the crew was snared by landing mode logic, indicate parallels with the Emirates 777-300 accident at Dubai five years later.

The SIA aircraft was affected by ILS interference as it flared for landing on 1 November 2011, drifting to the left as a result.

While the crew was prepared for an automatic go-around, the touchdown of the main landing-gear switched the jet to ground mode, inhibiting the take-off/go-around switches which would have commanded full thrust.

The same logic similarly disengaged these switches on an Emirates 777-300 which touched down at Dubai in August 2016, before its crew attempted a late go-around.

United Arab Emirates investigators found the pilots had received a warning that the aircraft had landed long.

The crew attempted to execute a go-around but the aircraft became airborne with only idle thrust, rather than the full thrust which would have been provided through the take-off/go-around switches.

With no manual intervention to advance the thrust levers, the Emriates 777 sank back to the runway and was destroyed by fire. All those on board the jet survived.

Investigators have yet to reach final conclusions over the Emirates accident, and determine the precise crew response, but the inquiry has already pointed out that the take-off/go-around switches are inhibited once the aircraft is on the ground.

German investigation authority BFU states that flight-data recorder information, plus a sonogram intended to identify sounds in the cockpit, indicates the SIA 777 crew “simultaneously” pushed the take-off/go-around switch as the left-hand main landing-gear contacted the runway.

“The crew anticipated that the go-around mode would initiate a go-around, but nothing happened,” it says.

SIA was training its crews on three 777 simulators, one manufactured by Thales and two by CAE.

All three used the same system logic as features in the 777 in order to activate the ground mode, and all three demonstrated that the go-around switches were ineffective if ground mode was active.

BFU says the Thales simulator switched to ground mode “a little later” than the CAE simulators once the main landing-gear made contact, without elaborating.

The inquiry says both the SIA captain, being an instructor pilot, and the experienced first officer were sufficiently familiar with the go-around procedure.

But it nevertheless is recommending that additional go-around guidelines be implemented, and that crews should have improved simulator training on go-around procedures after the aircraft has switched to ground mode.

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