Load Factor with flap!
Decreased flap is only ever required when the crosswind (or any wind for that matter!) is accompanied by an associated turbulence for the following three main reasons.
1. The maximum load factor for most aircraft decreases with flap…
For example, a PA38 has a maximum load factor that decreases from 4.4 to 2.0g with the application of full flap. If you are on a turbulent approach, regardless of the crosswind component, common sense suggests that you should fly the aircraft in a configuration in a way that allows the maximum load to be safely applied upon it.
Prolonged strong gusts on the aircraft with full flap can possibly cause structural damage – even if that damage is only contained entirely to the flap system itself.
2. Reduced Angle of Attack
The reduced AoA with reduced flap in anticipation of a relative gust of wind from under the wing causing a stall is certainly a consideration, albeit not a major one. The main consideration once again is a preventative measure against overstressing the aircraft. (Increased AoA as a consequence of change in RAF = Increased Load Factor… and when flap is down on the aircraft, it will tolerate a lesser LF).
3. Increased Controllability
Additional speed on the approach is simply to assist with the control of the aeroplane in turbulence. With reduced flap the approach speed is normally increased as a product of 1.3V(new)s.
You could perhaps argue that by coming in faster you are subjecting yourself to the crosswind for a longer period of time? The advantages far outweigh this disadvantage assuming the correct technique is applied.
Note that the deceased flap is only ever a possible consideration in turbulence. A strong calm wind in itself is absolutely no justification for reduced flap unless it’s a general consideration (i.e. collision, damage, rough strip, flap failure etc…)
As for stalling onto the runway in a crosswind! You’re altering the flying characteristics of the aeroplane fairly dramatically in awkward conditions and will result in a degree of uncontrollability. If you do this out of ground affect it can make for a very unpleasant ‘arrival’ indeed.
I worked at one school that stated flap was always required, and when available, on a landing “to ensure high drag and high RoD in the flare so as to minimise the effect of the crosswind”. I always debated this philosophy since I was a firm believer of applying a technique that fit the conditions – and using the Ops manual as an eduacted guide.
The above technique suggests that by coming in fast you subject yourself to the crosswind for a longer period of time – NOT that this is a problem for most aircraft, BUT will one-day cause concern if you use the technique indiscriminately.
I know of one situation in Central Australia where a company actually had an STC approved for the operation of an aircraft into a gravel strip without flap even though the POH implicitly implied that under the circumstances it wasn’t permitted. After much red tape, revised TOLD, laising with the manufacturer and flight testing it was approved.
There was a recent article written on crosswind technique in an Aussie Aviation mag as well, jumbojohn. The author is a newly christened Commercial Pilot and I personally think that she doesn’t have the instructional skill, technical knowledge, commercial exposure or experience to write on any operational subject with any authority.
The author was writing about a well-known and very well regarded Sydney flying school and their teaching techniques. I don’t think she came close to articulating the Instructor’s message. Although the article was in the interest of safety I would argue that it could have quite possibly had the opposite effect. This mag has some serious issues to address if they want a serious readership and need to revaluate their expertise and maybe even their duty of care before they continue with such widely read dribble.
Fly in compliance with your Flight Manual, Approved Pilot’s Operating Handbook (POH) or company SOPs (or Part B). Don’t apply a technique that hasn’t been tried, tested and approved by an approved mechanism.