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Old 30th Jul 2018, 19:27
  #15 (permalink)  
pattern_is_full
 
Join Date: Jan 2008
Location: Denver
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@John_Reid - on the serious side, it comes down the geometry of the specific aircraft type: length of wings relative to landing gear, additional "obstructions" such as below-wing engines, large airline flaps, etc. etc. And manufacturers' recommendations for each of their aircraft types.

When you get the type rating, you learn to do it "the Boeing way" or "the Airbus way" or "the Embraer way" for that aircraft. These days, that is most commonly (but not always) - crab until the flare, and de-crab with rudder while flaring.

Crosswind Landings

Some aircraft require weight-on-wheels for both wheels, or for the wheel that will touch down last in a slip to one side or the other, to activate the deceleration systems (auto-brake, spoilers, reverse thrust). And in some FBW aircraft, aileron control is intentionally limited at low radio altitudes, specifically to prevent a dangerously large bank at touchdown.

Now, that doesn't mean a given pilot can't botch the technique in a given landing, or get caught by a strong gust in the flare that raises a wing or leaves one heading for the grass.

In your post #8 videos, the famous Hamburg incident (video 3) was in winds 28/29 knots gusting to 47 knots, at 60° right of runway heading. Here's a report of what happened, which also quotes the technique recommended by Airbus in the A320 operating manual, and the Airbus limitation of aileron travel to 50% of "full" above 80 knots. Once the wind pushed a wing up, they had little authority to get things back to level.

Report: Lufthansa A320 at Hamburg on Mar 1st 2008, wing touches runway in cross wind landing

In your video 2, could be a gust, or just overdeflection of the rudder, resulting in too much swing with a super-heavy (A380) aircraft with a lot of inertia - it goes past center and zigzags to get back on track.

Video 1, I can't analyze due to distance, but it appears the crew missed the turn to final at old Kai Tak (probably also due to stronger wind than expected) and had little time to get lined up to begin with, and may have also caught a change in the winds in the flare (hilly terrain in 3 quadrants, lot of wind changes in the last 1000 feet down.)

None of those are excuses. Given the conditions or lack of a stable approach, a go-around (as opposed to a slip) may have been the right "corrective action." But the technique of crab/de-crab is used 1000s of times a day - successfully, and appropriately.

Last edited by pattern_is_full; 30th Jul 2018 at 20:00.
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