Quote
from Linktrained (January 13th):
"The flight had been briefed to be at 100 ft along R/W 34 L.
Perhaps due to the realignment with grass R/W 34 R the aircraft used some of its potential energy (now only height and airspeed, with flight idle having been set at 12.44.14) the descent to 46 ft became inevitable. This required more of a climb than hadbeen planned - or an earlier selection of TOGA by a few seconds ( 10 ?)."
Sorry to respond so late. First, perhaps it's worth reminding ourselves and others again that the fly-past was ill-conceived by the airline, with no provision made for a recce-flight or a ground inspection, and minimal preparation by both the airline and the crew. The notion of making an approach with a load of commercial passengers to a platform of 100ft QFE on an unknown non-runway (in A320 terms) - followed by a level-off, during which the a/c would be decelerated to within a couple of degrees of the stall AoA; followed by a high-alpha go-around - must rate as one of the most irresponsible in public-transport ops since the flying circuses of the 1920s and 30s.
Once committed, there would be little room for even one technical failure or significant crew-misjudgement. This crew seems to have made at least three serious errors in the execution of the briefed game-plan.
(1) The a/c arrived at the airfield boundary with far too much energy - kinetic and potential - to achieve the briefed game-plan of establishing stable flight at high AoA, using thrust to maintain speed in level flight during the transit of the airfield.
(2) The a/c levelled off at an indicated barometric height of about 60 ft above the reference altitude of the airfield - on both the pilots’ altimeters. (This assumes they had been correctly set to the QFE of 984 hPa, as announced in the CVR transcript). During the next 14 seconds before first impact, the barometric height fell slightly to about 50 ft, finally recovering to about 60 ft. Allowing for pressure-altimeter tolerances, together with the forward position of the static-pressure port and the aircraft’s high pitch-attitude, as much as 20 feet could be subtracted from the above values to “guess-timate” the actual heights.
It seems clear that, however foolish the airline and the captain were to plan the flypast at 100 ft on the QFE, the a/c would in all probability have cleared the trees had it been flown thus.
(3) The go-around was initiated too late to achieve any significant climb before the tree line was reached. In the event, insufficient time was allowed for the certificated time of engine acceleration from idle thrust, and the a/c was carrying a negligible surplus of kinetic energy to convert to any increase in altitude.
Prior to selecting TOGA thrust, the crew may have neither been aware of the horizontal distance to the tree line; nor the fact that the engine nacelles, landing-gear, and rear fuselage were lower than the tree tops. Their opportunities to recognise the hazard of the trees may have been limited: due initially to the rushed approach, and later to the visibility restrictions of the high pitch-attitude.