Flight International and Future A350 pilots `learn by doing`

[CONF iture]

Originally Posted by Owain Glyndwr

There is no way you are going to get – 0.5deg glide slope, or even the -1deg of the actual certification demonstration, with no thrust.

Absolutely you could. What matters is the vertical speed at splashdown.

That being so, why pick out 11deg pitch as being optimum for the engines out case?

11 degrees attitude is optimum for all cases, thrust or none.

The rate of descent though is more or less independent of AoA at impact because the aircraft, being thoroughly on the back of the drag curve, has a much worse L/D at higher AoA and the increased glide slope angle offsets the speed reduction.

Again, what matters is the vertical speed at touchdown. Don't flare too high and forget about the negative effect of the drag. That's where experience matters, and Sully had some.

I suggest that rather than restricting the actual pitch or AoA, the system actually attenuates the pilot input by changing the stick/elevator gearing. Somewhere I have either read or heard that in early flight test the aircraft was prone to PIO in the flare and that the laws were changed to eliminate this tendency. Reducing system gain would be a classic way of doing this. Such a feature would certainly have the effect of reducing the pilot’s ability to flare in a short period, but would not in fact be a hard limit on AoA.

If electronic cannot deliver the needed accuracy, experience is still a very valuable option. In his final attempt to improve the touchdown, Sully may have been better served with a direct law with no interference.

Those sentences make a nonsense of any assertion that the attenuation of pilot's control input in some mysterious way condemned the aircraft to never bettering - 3.5 deg FPA in the engine out ditching case.

Who made such assertion ?

[Owain Glyndwr]

Originally Posted by Owain Glyndwr
There is no way you are going to get – 0.5deg glide slope, or even the -1deg of the actual certification demonstration, with no thrust.
Absolutely you could.

I agree- my bad - I take that back.

Who made such assertion ?

Sorry, I thought you were from your remarks. If you aren't then that's OK isn't it

[Linktrained]

Water "landings"

Owain Glyndwr

I was told that the Solent ( and other?) flying boats used a very slow rate of descent (100ft/min? or less) from 300ft. to the surface, and at a suitably slow ASI. This helped with a calm (or obscured surface). No radar altimeter, then, but plenty of landing distance, usually.
Perhaps this was somewhat similar to the test pilot's -0.2 degree touchdown reported, but he had a radar altimeter.

I recall that the B47 was said to be rather fussy about its touch-down speed, NO " sit-up and beg" !

I tried to join Aquila, twice, but only flew on four sectors as SLF shortly before they ended in 1958.

[Centaurus]

I was told that the Solent ( and other?) flying boats used a very slow rate of descent (100ft/min? or less) from 300ft. to the surface, and at a suitably slow ASI

That sounds about right. Back in the mid- Fifties we flew Long Nose Lincoln Mk 31 on maritme recce. The aircraft carried lots of flame-floats and we would make a practice approach to ditching at night. It assumed we had not run out of fuel but would ditch before that happened. The flame-floats would be dropped in a line then the aircraft manoevred for approach. The technique was full flap, airspeed accurate at Vref and rate of descent adjusted by power at no more than 200 feet per minute until simulated impact. Glad it never happened for real because the Pacific had big waves out there.

Part of the standard instrument rating test in the Lincoln was to make a simulated ditching run on instruments at a safe altitude of around 2000 ft.

Gave a student a similar effort in the 737 simulator recently and it was clear the pilot was out of his depth (literally) and he would have torpedoed under on impact due lack of instrument flying raw data skills while attempting to fly in landing attitude at 300 fpm on instruments. That's what automation dependency does for you.