Crosswind Limits
 

My aircraft POH says, "a pilot of average skill should be able to safely land in a 15kt crosswind", and a placard inside the aircraft says, "maximum demonstrated crosswind 16kt". Nowhere is the word "limit" used.

Does this mean that it's down to the pilot's judgement? Or would an insurance company drop you like a hot potato if you had an 'incident' during a landing outside the crosswind limit?

Yes it is down to pilot skill and judgement and no it would not invalidate your insurance if you prang it during a landing with a 17kts X-wind.

It is not a lmitation.

IF my memory serves me well manufacturers only have to demonstrate that their mount is able to be landed with a crosswind component of at least 0.3Vs.

Nowt more nowt less.

That is why some STOL aeroplanes have a ridiculously low demonstrated crosswind, their stall speed is low so 0.3 * is going to be very low.

Maule = 12 mph.

They easily handle a lot more.

if it is not in the Limitations section of the POH, it is not a limit.

The factory test pilot was required to demonstrate a safe landing under available crosswind conditions using NO crosswind compensation (= very ugly). The test proved that the landing gear is strong enough to handle idiot pilots.

Thanks chaps. I've landed it with 16kt cross a number of times and the aircraft feels well within its capability. Always worth knowing the facts which are, as usual, at odds with clubhouse propaganda.

The C152 POH says there is a DCC of 12kts but it is not considered to be a limitation. From personal (supervised by a FI) experience it can be landed safely in a much greater crosswind than that - NOT that I would set out to do that, it's just good to know that, should the need arise, it can be done. :ok:

Agree on that count. When I was a student I (with instructor) landed a 152 in 25kt cross. It squirmed a bit, but no major problems.

I didn't know that. I assume this means a crabbed approach without kicking out the crab when you touch down? Ouch!

Does remind me of something else though. Apparently a 747, because of the outboard underwing engines, can't use the wing-down technique to land in a crosswind. So the recommended crosswind technique is exactly what's written above - no crosswind technique whatsoever. Just plonk it on the runway like you normally do, with up to 45 degrees of crab. The gear is strong enough to survive this, and since the main gear is behind the center of gravity, it will ensure the plane aligns itself with the flightpath/runway anyway. Videos on youtube, search for "fantastic video of crosswind landings"

Quite so, there was a little accident at Heathrow a while ago when in the middle of the flare a 747's outboard engine struck the ground. It is very easy to do I understand because the wings are so flexible and it only takes 8 degrees of contol deflection to put the engine on the ground when touching down.

Not all big jets can do that though....the MD11 apparently responds very badly to being plonked down still in the crab.

Like this :eek:

http://www.aviationpics.de/appr/slip747.jpg

Is that the Korean Air 747 that can be seem touching down on one wheel on YouTube?

It's a tough little nut isn't it? :) I know it's not all that popular in some circles, but I really enjoy flying it. It won't be that long before it's considered a "Classic" and then they'll all want to fly it. :E

I don't believe that's the case, Dirk. The test pilot isn't required to find a limit, but there's nothing in AC23-8 to suggest that the test pilot cannot use standard techniques for crosswind.

This came up a while back and I posted a link and some extracts here.
http://www.pprune.org/forums/showpos...6&postcount=18

The crosswond is demonstrated using both the crab and the forward slip techniques.

If the test pilot finds that one technique is unsuitable for the average pilot then the expected technique will be put in the flight manual.

The aircraft undercarriage must be capable of withstanding certain sideloads etc as per FAR-23 or CS-23 as appropriate. This may not be part of the flight test programme if the certifying authority accept an alternative method of demonstrating compliance.

The maximum crosswind demonstrated during test flying of the aircraft is specified in the flight manual. If you choose to use a higher figure then feel free to be a test pilot. However, please check your insurance for the small print about using the aircraft for development testing.

When you have demonstrated the higher crosswind, please let the manufacturer know......they will either amend the flight manual or recomend that you have the aircraft checked due to undercarriage side load limitations.

I wonder which? ;)

Regards,

DFC

I love it!

Should result in all sorts of .. .. ..

:)

Stands back and waits.

How does a properly executed wing-low landing put sideload on the undercarriage again?

Not so - the correct technique for low wing airliners is to use rudder to ease off the crab at the last moment (ie in the flare) whilst using aileron to prevent wing drop. Failure to squeeze off the drift places an uncomfortable load on the undercarriage - even if it not damaging in the short term, it's not good for fatigue in the long term.

I say this as a pilot of low wing jet airliners!

As for maximum demonstrated crosswind, whilst it may be LEGAL to exceed it, it's probably not SMART. As it is the maximum demonstrated, no-one can say for certain what the actual maximum safe crosswind is. Therefore, any excursion beyond the demonstrated maximum is a journey into the unknown.

Think about it this way - juggling with chainsaws is legal - but is is SMART for the average person to do it?

We have a simple rule at our FTO - we treat the maximum demonstrated as a limit. Full stop, no questions. That way we all know where we stand.

Unless the nose is pointing straight ahead down the runway and there is absolutely NO side drift there will be sideload on the gear. Have you ever carried out a perfect x-wind landing where this has been the case (no side drift, nose pointing exactly ahead)?

During certification according to FAR part 23 the applicant is not required to demontsrate the emptying of the ashtrays during flight (nor, for that matter on the ground). There's no reference to the procedure in the AFM. Do I become a 'test pilot' when I attempt this manoeuvre? ;)

Doesn't the maximum demonstrated crosswind for landing just depend on the wind strength on the day that part of the certification was undertaken?

You make it sound like it's the holy grail or something. I learnt at, and am now based at Leeds, so yes, I have thanks. I know a lot of people are terrified of crosswinds, but one adapts to one's surroundings. A lot of GA fields have the luxury of multiple runways and some PPLs have never had to deal with a crosswind landing, but as with everything it's all about practice. During my training I did several circuit sessions which consisted of flying along 3ft above the runway for 1000m or so at 60kt in a 14kt xwind, wing down, anchored to the centreline, before doing a touch and go.

I flew recently with a friend who learnt at Sherburn. As we headed back towards Leeds I had a listen to the ATIS and the surface wind was 260/14 for runway 32. The whole concept of flying sideways on final, then landing left wheel, right wheel, then nosewheel was completely alien to him.

Not saying I'm any better or worse a pilot than anyone else, but I know how to land with a crosswind. It's a handy skill, maybe more people should learn it :rolleyes: