PPRuNe Forums - View Single Post - Emirates A380 crosswind at Schiphol today -- question about technique
Old 22nd Nov 2016, 15:48
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Chris Scott
 
Join Date: Jan 2008
Location: Blighty (Nth. Downs)
Age: 77
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Good morning in California, sshanky, and welcome to the PPRuNe madhouse of whingeing, armhair experts!

Is this the video you're referring to?
Emirates A380 lands at Schiphol Airport in Amsterdam during Storm Angus | Stuff.co.nz

If so, it was likely taken at the weekend, rather than yesterday, Easy for Dave Reid to talk, but in fact I entirely agree with him.

To be more specific, the handling pilot or autopilot (more likely the former, as autopilots traditionally have lower crosswind limits) has done a decent job in a fairly strong crosswind - as far as one can tell from the evidence of the low-positioned camera.

The runway could best be described as "very wet", which has a relevance to the landing technique in at least two respects:
1) Firm touchdown required to break through the water to the hard surface, ensuring main-wheel spin-up for subsequent directional control and braking;
2) Following from (1), no need to de-crab fully before main-wheel touchdown. The reaction of the tyres to the side load will be much less than on a dry runway.

In this case the pilot over-flares, and then seems to de-rotate slightly to settle the main-wheels on the runway.

You are right that, on a dry runway, landing without de-crabbing puts an unnecessary stress on the main gear assemblies and - coupled with the into-wind weather-cocking effect after touchdown - can potentially lead to the aeroplane veering upwind before nose-wheel touchdown. However, the great inertia of a big jet tends to mitigate that effect, and landing-gears are designed to withstand the drift angles involved.

Before someone pulls me up, must admit to no knowledge of the A380, but I notice that reverse is deployed on the inboard engines only. If all 4 engines are fitted with thrust-reversers, that may be a precaution in crosswinds? Judging from the resulting spray, which advances almost to the intakes, full reverse was used.

PS
I see RAT 5 has got in first while I got sidetracked. Yes, the other crosswind technique is to make the approach with the appropriate direction and amount of sideslip to enable the fuselage to be aligned with the runway centreline throughout. So the upwind wing is low, and the aircraft kept straight with enough downwind rudder. The upwind main gear lands first, after which the pilot allows the downwind wing to settle to wings level, keeping the fuselage straight with rudder. However, many big jets are limited in the bank angle at touchdown by outboard engine pods and/or trailing-edge-flap extremities. Also, any remaining coffee cups will slide off the side of the fold-down tables...
Nevertheless, as RAT 5 says, the compromise is for the pilot to fly a crabbed approach, but to lower the upwind wing slightly during the flare and de-crab. That normally works well.
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