SWBKCB, basically the problem on take-off is that the aeroplane will try to weathercock into wind before it is travelling fast enough for the rudder to be effective - so the pilot will need to rely upon nosewheel steering early in the take-off roll - and that has limited authority as speed increases. The skill comes in transferring smoothly from nosewheel steering to rudder during the take-off roll.
For that reason, I always chose a full power take-off in strong crosswinds to minimise the time on the runway.
Another problem is that the into-wind wing will try to lift in a strong cross-wind; this can be worse in swept wing aeroplanes if the pilot needs to use a lot of rudder quickly in the downwind direction to counteract an unexpected gust causing weathercocking. So in conventional aircraft, a significant amount of into-wind control column deflexion is also needed, which will change as the aircraft acclerates.
All-in-all, there will be a fair bit of fancy footwork and skilled coordination going on during a crosswind take-off! Then, when the aeroplane becomes airborne, the pilot has to turn the aircaft into wind to maintain the required track as well as coping with turbulence before the autopilot can be safely engaged. Perhaps more of a challenge in conventional aircraft than in 'fly-by-wire' Airbus aircraft whose flight control computers assist the pilot extremely well as soon as the aircraft becomes airborne and the 'control law' blends from 'ground' to 'normal' flight in the first 5 seconds of flight.
However, the crosswind limit takes into account handling by an 'average' pilot - so you can rest assured that if the wind is less than the limit, conditions will be more demanding than on calm days, but not impossibly so.
I note that there are already differing opinions on various met websites regarding the threat posed by tomorrow's weather - fingers crossed that the lurid picture being painted by the BBC will turn out to be somewhat exaggerated!
Last edited by BEagle; 9th Mar 2008 at 10:40.