Quote from IGh:"...this A320 lost 7-kts sometime in the flare. The PF controlled the PITCH-up response to the late sinker:
?? Was the A320's Thrust Mgt System suppose to respond with added POWER??"
[unquote]
Difficult to answer, as the published report leaves too many relevant questions unanswered, and we don't have the DFDR traces. These would be particularly helpful to establish the time span between the 2 reported touchdowns, and also to see if the main-wheels may have nearly left the ground a second time around the time the tail-strike occurred.
Quote from the report:
"At about 1202, as the flight was entering the DEN terminal area, the crew briefed an approach speed of 139 knots for a visual approach to runway 16L."
We do not know the SOPs in use. In A320 operations, however, it is not normal to brief a fixed approach speed, because in "managed speed" this will be reviewed constantly by the "GS-MINI" feature. What would have been briefed, however, is the VLS (VREF) for Flaps3. This figure is calculated by the FMGC, and displayed on the PERF page, but may be overridden there by the crew. Once the crew enters a surface-wind, the FMGC calculates and displays VAPP, which may be higher. This will be scrutinised for gross error. (CONF iture, please confirm?) With "managed" speed, GS-MINI never allows the airspeed target to fall below VAPP, but always increases it if necessary, to maintain a ground-speed not less than it has calculated for the threshold.
It is perfectly possible to fly approaches in "selected" speed, using the speed knob on the FCU; but inadvisable, because you lose the airspeed protection provided by GS-MINI.
The report (as published) does not cover any of these differences.
The stated LW was 140,000 lb (just under 64T). A VLS (VREF) for Flaps 3 of 139 sounds a bit on the low side to me, but my manuals are out of date. [Can anyone help?] We must assume that the crew had planned to land with Flaps 3, as the report does not state otherwise, but there is a small element of doubt in my mind.
The latest METAR available to the crew at the briefing stage appears to have given a wind of 240/4 kt, so it is likely that VAPP would have been the same as VLS.
The report continues:
"The First Officer (FO) was the pilot flying (PF) and reported the approach was stable at 1,000 feet above the runway threshold. At 1216:15 ATC cleared the flight to land and issued a wind advisory of 260 degrees at 5 knots. The flight crew extended the gear and selected flaps 3."
When the PF reported approach "stable", were gear and Flaps 3 already extended? The last sentence above seems to suggest otherwise, which seems odd. The final wind report (260/5 kt) from the Tower must have been due to change: about 30 mins later it was 330/13 kt, which may explain the tailwind they got on the approach from the north-west.
The displayed speed target should not have dropped below VAPP, whatever that was (139?). The A/THR should have tried to maintain that (or greater), until the PF selected idle thrust (during the bounce). The report says the DFDR indicated the tailwind was as high as 11 kt, late on the approach, but does not state a touchdown figure. If it had disappeared by the threshold, that would represent a headwind-shear...
The high VS of 800 ft/min at 50 ft probably reflects the high TAS (at over 5000ft amsl), plus the tailwind. If the flare was started at 45 ft, that should have been more than early enough.
So, to try and answer IGh's question, the facts are: the PF pulled hard to try and achieve a respectable touchdown; there was a loss of IAS; and the A/THR failed to arrest this. Why? The best I can come up with is: thrust would have been lower than normal, due to the high VS, and there may have been a further, sudden tailwind-shear during the flare. In my opinion, the loss of speed was not due to anything peculiar to Airbuses, or the CFM-56. As for any comments on sidesticks, and/or the ground-spoiler logic, I'll try to leave those to CONF iture. He and I have been there before...
For what it's worth, I would have preferred to use Flaps Full. Would also like someone to check, please, if that reported VAPP of 139 kt was enough for Flaps 3.
Chris