Must beg the forbearance of you military and ex-military types for one of my occasional intrusions into your forum. But, as you seem to be talking about the comparatively banal task of landing transports, I reckon we've all been playing the same ball-game. Like
RetiredBA/BY, since retirement I've been surprised by the increasing prevalence - judging from videos taken from near the approach lights - of guys making no noticeable attempt to de-crab. The
Boeing video from
Duchess Driver shows four landings, of which only the third shows a full de-crab. The fourth shows a partial de-crab with the simultaneous introduction of a little wing-down. When test pilots refrain from de-crabbing, they would no doubt tell us they were simply demonstrating that the L/G can cope with the sloppiest technique on a dry runway...
Plenty of good stuff here, but I'll take this one for discussion:
Originally Posted by
H Peacock
Wing-down will always work, ensuring you land with no lateral drift, but it does mean a podded engine may be too close to the ground. Conversly, if you elect to crab, then unless you get it exactly right you're either going to land with lateral drift (ie you kicked the drift off too soon) or you'll still be crabbed off (ie kicked the drift off too late).
Agreed, except that, as well as PPPP-PP, practice helps. Unfortunately, the long-haulers don't get much of that.
Originally Posted by
H Peacock
Of the various RAF ME types I've operated I've used both techniques, or even a blend of them (ie a bit of wing down but also some crabbing). The geometry of the tailwheel types requires them to be flown accurately aligned and with absolutely no lateral drift - so had to be flown wing-down, but also to a relatively low crosswind limit. The tricycle types will always yaw themselves straight after touchdown if you've not got it right, but it can feel very uncomfortable and can't do the gear much good.
Agreed, although
Onceapilot has a point.
Originally Posted by
H Peacock
Dont think I've ever seen a modern airliner using the wing-down technique.
Evidently not a 'plane-spotter!
IMO, the (roughly-speaking) three dry-runway techniques - [1] wing-down; [2] slight (late) wing-down during de-crab, and [3] wings-level (full) de-crab - are chosen as appropriate to the aircraft type.
Looking back on a short-list of various types, the following are my suggestions.
Heron [3] or [2], but minding the upwind prop.
C-47: [1], and wheel it on.
Dart Herald: [1], but avoiding wheel-barrowing and ensuring downwind wheels firmly on the ground before using any downwind brake
.
VC10: [2]. Although the only limiting factor was the outboard flaps, I never saw [1] demonstrated, and perhaps the tanker guys will comment, pod-wise;
B707-320 (JT3D turbofans): [3], due to outboard engine nacelles, but no doubt the experts could use [2]. The later KC-135s with CFM-56 engines presumably stick with [3]?
BAC1-11: [1] or [2].
A310: [2], bank slightly limited by engine nacelle;
DC-10: [2], although the auto-land adopted [1] at 138'R - but only enough for a 20-knot crosswind, if memory serves. Cockpit needed to be well upwind of the centreline prior to de-crab.
A320: [2], although - being FBW - the manufacturer recommended [3], claiming that the zero roll-rate command from the side-stick would prevent the upwind wing rising during de-crab, and that crossed controls were not recommended. But [2] works very well. I imagine the A330-200/Voyager (with similar FBW) would be comparable?