Crosswind Limits

[Shunter]

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?

[Flyin'Dutch']

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.

[dirkdj]

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.

[Shunter]

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.

[DX Wombat]

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:

[Shunter]

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.

[BackPacker]

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.

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"

[Contacttower]

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.


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.

[Shunter]

Like this :eek:

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

[Contacttower]

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

[DX Wombat]

It squirmed a bit, but no major problems.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

[bookworm]

The factory test pilot was required to demonstrate a safe landing under available crosswind conditions using NO crosswind compensation (= very ugly).

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/showpost.php?p=3022826&postcount=18

[DFC]

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

[Fuji Abound]

When you have demonstrated the higher crosswind, please let the manufacturer know......

I love it!

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

:)

Stands back and waits.

[Shunter]

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

[moggiee]

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.
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.

[SkyHawk-N]

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

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)?

[bookworm]

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.

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? ;)

[soay]

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

[Shunter]

Have you ever carried out a perfect x-wind landing where this has been the case (no side drift, nose pointing exactly ahead)?

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:

[MidgetBoy]

Hah, that question killed me on my flight test.
"So can we land at this airport?"
"No, there is a crosswind of 19, the aircraft can only maintain 15kts."
"Actually, that's just what the maximum demonstrated was, I'm sure by the time you finish your commercial license you can do a 19kt crosswind landing."

As of today, I've tried a few times, max I can hold is a 17kt in a 172M model and it isn't fun either.

[Gertrude the Wombat]

"So can we land at this airport?"
"No, there is a crosswind of 19, the aircraft can only maintain 15kts."

However a reply of:

"No, there is a crosswind of 19, I have decided that for the time being my personal limit is 15"

would be fine. (As long as you'd thought up, in advance, your answer to the obvious next question: "so, if you knew you weren't going to be able to land, why did you take off then".)

(Having said which I did take off the other day knowing full well that I wasn't going to attempt the landing due to the crosswind. It was an IMC lesson, and I did tell the instructor before we started that I wasn't going to take off unless he did the landing, so no problem.)

[dirkdj]

Bookworm,

This info comes from a Beech engineer who was present during certification of the BE35, he is dead now unfortunately. The demonstrated crosswind landings need to be done in front of official observers to count.

I have done landings myself at twice the demonstrated crosswind component of my aircraft but I have more than average time on type. It took more than average skills to do that and I am not sure I want to try it again.

[IFMU]

Have you ever carried out a perfect x-wind landing where this has been the case (no side drift, nose pointing exactly ahead)?
For us taildragger guys, it is preferable to do one of these 'perfect' landings rather than ground loop. It always helps to have lots of practice, tugging gliders has given me this opportunity. I'm currently working on my instrument rating in an Arrow and it lands fine in crosswind too, just have to remember to kick the rudder out before the nosewheel touches down.

-- IFMU

[Chuck Ellsworth]

Have you ever carried out a perfect x-wind landing where this has been the case (no side drift, nose pointing exactly ahead)?

Yes, thousands of them, in fact that is what I strive for on every X/wing landing.

And generally I succeed in touching down pointed straight down the runway with no sideways drift.

[Pilot DAR]

"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."


Sounds like an idea in theory, but if the rental pilot leaves with a light crosswind, and returns to a stronger one, do you send him away?

[bjornhall]

Then there are those of us for whom the max demonstrated crosswind is limiting... In Sweden, max demonstrated is the legal max limit. Sensible or not, inconvenient as it is, that's what the law says... *shrugs*

[MidgetBoy]

"No, there is a crosswind of 19, I have decided that for the time being my personal limit is 15"

would be fine. (As long as you'd thought up, in advance, your answer to the obvious next question: "so, if you knew you weren't going to be able to land, why did you take off then".)
Oh, it was the ground part of the flight test. The runway length also wasn't the best to try a 19kt crosswind for a first either.

[DFC]

Never mind the perfect wing down landing with no drift.

Jack up one side of your aircraft so that the main wheel on that side is clear of the ground and tell me that there is no side-load on the other main wheel. Now lift the aircraft clear of the ground in that attitude and drop it from 6 inches and tell me that there was no side-load. That is not even close to the requirements.

While personal limits are good, commercial pilots are expecetd to be able to fly to the limits imposed by the flight manual and the ops manual. having an FTO ops manual with an approved crosswond limit of 17Kt and saying to the examminer that while the manual says 17, my personal limit is 12 without further realistic justification on a CPL flight test will not go down well.

Perfectly acceptable and very commendable however as a PPL because no one is going to be paying you to perform to a certain standard.

Regards,

DFC

[FullyFlapped]

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?


DFC,

OK, I've just done exactly that. Here is the main body of the letter (with my details removed):-

Customer Services
Cessna Aircraft Company
P.O. Box 7706
Wichita KS 67277

11th November 2007

Dear Sir/Madam,

I am the owner of a UK-based XXXXX, and I would very much appreciate your advice.

The POH for my aircraft state that it has a demonstrated crosswind landing velocity of 21 knots. Three days ago, I was forced to execute a landing with a crosswind component of around 28 knots.

I executed a crabbed approach followed by a wing-low landing, touching down the right main wheel first, then the left and finally the nose wheel having centralized the rudder. This seemed to work perfectly and is a technique I have used many times.

However, I have been advised by someone who claims to have vast knowledge and experience that I should inform you of this occurrence, as he feels that you will either wish to modify the POH for the aeroplane, or that you will now advise me to have the aircraft checked for “under-carriage side load limitations”.

Are either of these comments correct ? Or is what I did (as I believe) perfectly OK, because the demonstrated capability which is contained in the POH is not intended to be a limitation ?

I understand that any comments which you might make will be on a “without prejudice” basis, but I really would be grateful if you could help clarify this matter.

Many thanks,

----------------------------

I will publish the reply.

FF :ok:

[dirkdj]

Did you have official FAA experts witnessing the landing?

I have written similar letters to the other Wichita based aircraft company several years ago and am still waiting for reply.

POH's are written by engineers, then rewritten by the marketing department, then completely rewritten by the legal department.

[The Flying Pram]

I get the impression that most manufacturers "Demonstrated Crosswind Landing Limits" are erring on the side of caution. Presumably for product liability and insurance reasons. There are some aircraft with landing gear known to be at risk of side loads, yet the majority seem to handle landings at greater than these demonstrated figures without problems. I would have thought the sensible thing for designers to do is make the control authority the limiting factor. The other thing mentioned in this thread is training. I did mine at a school with multiple runways, so coping with crosswinds was not something I got that much experience of. Having operated from a single runway for 15 years now, my knowledge is considerably greater. I personally feel that a bit more training should be carried out with respect to short/narrow/crosswind runways. How many times have we read accident reports where the pilots first experience of small airfields was unfortunately not a very pleasant one?.

[Shunter]

I will publish the reply

Good call. Look forward to reading that :)

[Contacttower]

I certainly always get the impression that the xw "limit" was more about how far the test pilot was prepared to push the aircraft during testing and the level of wind at the time (apparently the Tristar's autoland would be certified for a 35+ xw if they had found such a wind at the time) rather than a true reflection of how good the aircraft is. The Bulldog for example has a demonstrated figure of 35 which is insane for a light aircraft, but part of that is surely that the test pilot on the day had the 'luxury' of a 35 knot wind and was maybe a little bit braver than your 'average' test pilot.

The PA28 can take more than 17knots (as I discovered doing solo circuits during my PPL :=). But the Cub I would never, ever push beyond its limit.

[DX Wombat]

The other thing mentioned in this thread is training. I did mine at a school with multiple runways, so coping with crosswinds was not something I got that much experience of. Having operated from a single runway for 15 years now, my knowledge is considerably greater. I also learned at an airfield with, in my case, three runways but I had an excellent FI who ensured that I got plenty of crosswind landing practice by waiting until there was no other traffic in the circuit then requesting a runway change. Multiple runways doesn't have to equal poor training.

[Contacttower]

Multiple runways doesn't have to equal poor training.


True, but currency is so important with crosswinds. During my PPL I went through a phase of the wind often being near the 17k demo for the plane (at a single runway airfield) and soon became an expert at crosswind landings...then after my PPL I went a while without facing a serious crosswind. Then I had a check ride to fly the club's almost brand new Archer and was faced with a 17k crosswind...I really struggled and to my embarrasment the instructor said to me "I have control...just let me show you how to make this easier". In short I had got rusty in only several months.

Multiple runways I think do lead to less crosswind currency.

[MidgetBoy]

Multiple runways I think do lead to less crosswind currency.
But don't you find it more fun to land with a crosswind?
I always request a runway for a crosswind if possible.

[Contacttower]

But don't you find it more fun to land with a crosswind?



I'll admit...I do relish the challenge.

My home airfield is single runway so most of the time the question doesn't arise anyway. Landing away I usually just take the runway I'm given...mostly because circuit traffic dictates that but also because funnily enough taking the runway that is NOT facing into wind doesn't usually occur to me!

[The Flying Pram]

But don't you find it more fun to land with a crosswind?

It's alright for you lot, I don't have the luxury of a rudder to kick the drift off! Come to think of it I don't have an elevator or ailerons either...

I discovered many years ago that is possible to land a flexwing microlight on tarmac in a 15 gusting 25kt - 90degree crosswind. I still remember the faces peering out of the club house as I taxied (very carefully) towards the apron.

Later the same day, having enlisted several helpers to de-rig my machine and put it in a hanger, I accepted the offer of a trip back to base with the farmer who owns the grass strip I use. Not by road, but in a PA18 Cub! After a particularly bumpy flight he got it into the 300 x 10 yd runway on the 3rd attempt. By this time our local Airport was reporting gusts up to 31kts. I believe the Cubs POH doesn't mention a specific crosswind limit, but leaves it up to the pilots discretion.

I don't fly in those sort of conditions nowadays.
Old pilots, NOT bold pilots??

[Contacttower]

In the POH for the PA18-135 I fly it states 10 knots as the max demo xw...I did once hear someone claim to have landed one in 20 knots...but after a friend of mine ground looped one in almost still air conditions I won't be pushing my luck ;).

[MidgetBoy]

I don't like pushing the limit too far either, but when you're time building in bad weather and all you can do is do circuits for 5 hours straight, you get bored and want to try something different.

[DFC]

FullyFlapped,

It might have been quicker if you had sent it to the flight test department but it will probably get there after much of the "hey did you see what this idiot has done" internal emails.

So what test pilot training scheme have you graduated from?

Your test cards must make up an impressive attachment to the email you sent.

Your analysis of the results and the in depth report recomending the increase in maximum demonstrated crosswind component will no doubt make waves at Cessna.

You will obvously also be able to justify yourself to the CAA test flight department who have also test flown the aircraft before acceptance onto the register and who will probably say......let's stick with what has been safe and efficient for the last 50 years.

Waiting for the Avweb joke....did you hear about the guy who did some home testing of a production aircraft.

I have been involved with an aircraft and test flight. One type in current production was tested to the mid 20Kts crosswind. However, the limit that was agreed for the flight manual was 15Kt. Why?......because the flight manual is and must always be for the average pilot with average skill.

:D

Regards,

DFC

[Life's a Beech]

DFC

A bit patronising if FullyFlapped turns out to be an experienced pilot with a lot of time on type, and if he took the right approach, with the right frame of mind. It doesn't take a test pilot.

I have landed (on a private flight I hasten to add) with a 30G40 at 70 degrees from runway heading, in an aircraft with a demonstrated crosswind component of 17 kts. BUT (and notice it's an important but) I had several hundred hours on type. I had landed before on a huge, wide runway in slightly lighter crosswind, so I knew the capability, and I flew for a go-around. Had the conditions not been perfect in the flare I was ready with the throttles, I had accepted that I was probably going to have to climb away to take the (short, grass but into-wind) cross runway.

When I was become an FI my instructor sent me up in a 26-kt crosswind in an aircraft with a demonstrated crosswind of 12 kts. He knew it was easily capable.

Demonstrated crosswind components were never meant to be limits, or they would be called such. They are recommendations intended to show what a mediocre pilot would be able to cope with and not break the aircraft, and as a sensible limit for most commercial operations (the operations manual will make the demonstrated crosswind a mandatory limit) to give greater safety margins.

[Fuji Abound]

I have yet to come across an GA type that cannot be landed in winds stronger than its demonstrated component and I doubt there are many over say a year old that havent been landed at more than their demonstrated component.

Does this increase leg fatigue?

Every landing causes some fatigue, some landings cause more fatigue than others (and not only the cross wind ones), and some pilots cause a lot more fatigue in more ways than you will ever know. :D

[DFC]

I have yet to fly an aircraft that can not be landed or taken-off in less than the distance specified in the flight manual.

The CAA and the insurer will ignore the 50,000 previous times you landed in a 50 knot crosswind if you break the aircraft while landing in a 20 knot crosswind when the max demonstrated is 15.

----------

Life's a Beech,

Your instructor would have been guilty of manslaughter if you had killed yourself.

The point is that FullyFlapped is by definition claiming to be a test pilot and consequently will have prepared in advance a test flying programme, have appropriate test cards as well as data obtained and will have a report that because of their credibility as a test pilot will be acepted.

I have been involved in test flying for a few years but still operate under the supervision and guidance of a more experienced pilot (as well as a flight test engineer) and must submit all reports through the designated senior test pilot.

Getting away with it and living to write an email is not test flying.

Regards,

DFC

[djpil]

POH's are written by engineers, then rewritten by the marketing department, then completely rewritten by the legal department.
At least part of the POH is the approved AFM which includes the section on limitations. i.e. approved by the FAA or equivalent.
I was involved in a mod to the landing gear of a Pitts S-1 - RV type gear (and Haigh tailwheel) instead of the bungees. We happened to find 25 kts xwing when we did our tests so submitted that in the AFM and the response was we could either leave it as 17 kts or have the authority's TP confirm it.

[Fuji Abound]

The CAA and the insurer will ignore the 50,000 previous times you landed in a 50 knot crosswind if you break the aircraft while landing in a 20 knot crosswind when the max demonstrated is 15.

I cant imagine they would - it could go horribly wrong.

So you are telling the Court that you meant to use the word "limit" but actually wrote "maximium demonstrated".

Hmmm, could end up with a product liability suite me thinks.

I would rather be defending.

[Chuck Ellsworth]

X/winds can be a real problem when flying in areas with poor or no weather reporting and forecasts.

So when I get to a destination with a X/wind that exceeds the demonstrated X/wind component of the airplane I will land it if there is no alternate available....

Unless they design an airplane that I can just park over the airport and wait until the wind changes.

[DFC]

How much for the Authority Test Pilot? or did you bother to ask? :ooh:

Regards,

DFC

[Fuji Abound]

Chuck - I was wondering if you call a Pan so as to enable you to do something that would otherwise be illegal?

[Chuck Ellsworth]

Chuck - I was wondering if you call a Pan so as to enable you to do something that would otherwise be illegal?

Call a Pan?

Why would I call a Pan every time I landed with a X/wind that exceeded the demonstrated X/wind of the airplane?

If it is illegal then there are thousands of us flying for a living that do it because we had no other choice but to land.

Here is a question for you...

Many years ago we were hauling fuel with a DC3 in Canada's high Arctic the weather was perfect until our last trip.

Sixty miles out of Resolute (our destination ) the FSS called us and informed us that a sudden unforcasted wind had come up and Resolute was going below VFR limits in blowing snow.

By the time we were on final for the runway the FSS gave us another update.
Visibility zero in blowing snow and the wind was 50 knots 90 degrees to the runway.

It was dark and we could see the runway approach lights and the runway lights on final approach but only dimly in the blowing snow.

What should I have done with no alternate?

Declared a Pan?

WTF good would that nonsense have done me?

I landed it with the 50 knot X/wind and the sucker just slid straight down the runway. ( As I knew it would. )

[DFC]

Why would you transmit a PAN at the planning stage?

No weather info for destination means an alternate is required where the weather is suitable should a landing not be possible at the desination.

Furthermore, telling everyone that you have an urgent message to transmit but do not require assisteance may not be appropriate if caught out in such a situation.

regards,

DFC

[Pilot DAR]

Some of the writers here have read CAR 3, the CAR 3 Flight Test Guide, and FAR Part 23 many times, and understand the deliberate choice of terminology required by those documents.

It seems to me that it would be a great benefit for others here to at least have an awareness of the content of these documents. A lot of the silly comments here (and a response requested of Cessna) could have been saved by doing the homework first!

Pilot DAR

[FullyFlapped]

DFC,

Thank you for the insults in your previous posts. I see that you're now a test pilot as well as having the many other areas of expertise to which you have referred over the years : what a fantastic career you must be having.

As to myself, when I'm not pretending to be a test pilot, or acting as an idiot, or making myself the subject of Avweb humour, I'm just a guy with many hours on type who can read ... hey - let's see if you can too !

Here's a verbatim quotation from my POH ...

"Demonstrated Crosswind Velocity is the velocity of the cross-wind component for which adequate control of the airplane during takeoff and landing was actually demonstrated during certification tests. The value shown is not considered to be limiting." (my emphasis).

Good luck with the test pilot phase of your long and oh-so-varied career ... :rolleyes:

FF :ok:

[Contacttower]

Your instructor would have been guilty of manslaughter if you had killed yourself.



I slightly doubt that DFC, gross negligence maybe but manslaughter?...Hardly. If you are doing a FI course then you're already going to be reasonably experienced and dead or not the AAIB will surely note that the ultimate responsibility lay with the idiot who agreed to go up in said wind in the first place.

[IFMU]

The PA28 can take more than 17knots (as I discovered doing solo circuits during my PPL ). But the Cub I would never, ever push beyond its limit.
I learned to fly in a member of the cub family, a 1946 PA12. As a student pilot I landed in the biggest xwind I ever have, during a solo cross country. It was pretty much 20kts across the runway. I find the cub series to be good crosswind airplanes. The super cub has the one issue where if you pull flaps in you can only get so much left aileron in, because the flap handle blocks your leg which then blocks the stick.

I fly pawnees too, in the really big crosswinds I worry about dragging a wingtip because it's a low wing. But I never have. I'm also known to cheat and takeoff/land a little into the wind rather than right down the centerline when it's sporty.

-- IFMU

[Contacttower]

It was pretty much 20kts across the runway.


All I can say is that you're a braver man than I...for my taildragger check out I had to fly in 8-10knots xw (while me instructor watched me from the ground) and I have to say on a rather muddy, slippery field the prospect of doing anything stronger was not very appealing.

[Fuji Abound]

WTF good would that nonsense have done me?

I could not agree more. I wasnt being serious - sorry a bit of a strange sense of humour.

I was seeking to make the point that IF it was "illegal" to land with a cross wind over that demonstrated then presumably the pilot would have to declare a pan or mayday because he could reasonably expect the uc to collapse on landing.

For me the fact remains that these days with such a high risk of product liability etc if the lawyers had intended to say LIMITING then I think they would have managed to use that word in the POH - if the word LIMITING is not used then I think it is entirely reasonable for the pilot, insureres, CAA and any one else who cares to comment to consider it to be demonstrated NOT limiting.

In short, I dont understand and you havent convinced me DFC, why you believe otherewise?

[S-Works]

To be fair some of the authority tests pilots are not all that. Ask my neighbour who handed over his turboprop converted glassair for test flying and had it left as pile of parts at Conington!!!

[DFC]

"Demonstrated Crosswind Velocity is the velocity of the cross-wind component for which adequate control of the airplane during takeoff and landing was actually demonstrated during certification tests

Here we are dealing with fact. Something that has been demonstrated, has been checked and which has been certified and something that the average pilot can repeat on a consistent basis.

The value shown is not considered to be limiting

That is opinion or speculation and is not based on any calculation demonstration or result.

What is says it that adequate control exists at the max demonstrated crosswind. It may or it may not exist above that figure.....if you want to try and find out, don't blame us if the aircraft breaks or you hurt yourself.

Your insurance company will expect you to take reasonable care. Test flying is prohibited by most policies.

Regards,

DFC

[Fuji Abound]

The value shown is not considered to be limiting.

DFC - so why would the lawyers add this in the POH?

An aircraft I fly is placarded to say I MUST NOT perform certain aerobatics if certain conditions are not met.

I can find no placard to say I MUST not land if the cross wind component is above a certain figure.

Why is there a placard for the first (and I might never fly aeros in the aircraft) but not for the second, given at the very least I am hopefully going to land after every flight.

[DFC]

Fuji,

Do you know that the legal department added in that piece?

The placards in your aircraft are giverned by regulation - the certification standard and the mandatory ones will be listed in the Type Certificate Data Sheet.

You will find all the limits on the Type Certificate Dats Sheet.

You will not find the Stall Speeds there. Do you think that they are limiting in any way? :)

You will not find that airfeild performance figures there. Do they limit you in any way?

As I said near the start of the debate. Feel free to be a test pilot if you want. Check that test flying is permitted by the insurance policy because valid insurance is mandatory.

You might also like to check the legal conditions required for test flying especially the ones regarding the carriage of observers etc etc.

Regards,

DFC

[FullyFlapped]

That is opinion or speculation and is not based on any calculation demonstration or result.

Are you seriously suggesting that an aircraft manufacturer's lawyers - in the USA of all places - would allow speculation or unproven opinion to form part of a POH?

Do you honestly think that nobody at Cessna would have flown the aircraft at higher x-wind speeds than the MDCV before making this statement in the POH ?

Honestly ? And you call me an idiot ?

FF :ok:

[Fuji Abound]

Do you know that the legal department added in that piece?

Do you know they didnt? And if they didnt you bet they reviewed it. And if they didnt review it then they had better look out.

and 2wit, as you know, no one is saying you should NOT stall most GA types, otherwise that would be one less task for the flight trainers.

.. .. .. and so back to which, since it would seem clear most manufacturers

are able to grasp the use of plain English by virtue of being happy to liberally sprinkle the POH with "limiting" and "prohibited" and such other clear wording I shall hold on to my belief that if they wished to limit me to their demonstrated component they would have said so - and that shall remain my defense!

[Pilot DAR]

Ok, As it appears that only DFC has really done his homework here, and understands where the term "demonstrated" originated, here's the standard:

3.145 Directional stability and control
(a) There shall be no uncontrollable looping tendency in 90-degree cross winds up to a velocity equal to 0.2 Vs0 at any speed at which the aircraft may be expected to be operated upon the ground or water.
(b) All landplanes shall be demonstrated to be satisfactorily controllable with no exceptional degree of skill or alertness on the part of the pilot in power-off landings at normal landing speed and during which brakes or engine power are not used to maintain a straight path.
(c) Means shall be provided for adequate directional control during taxiing.

So the aircraft manufacturer's lawyers are going to go to court and say "our test pilots did that, and here's the report." If the test pilots did more, and you can bet that they did, the manufacturer is not going to tell you that. There are lots of things they are not going to tel you.

Cessna used to produce a document called "Getting the maximum performance from a Cessna 150". I saw it once. Try to get a copy now!

My Cessna has a stated demonstrated crosswind value, which I'm sure meets the aforementioned standard. It also has an STC'd STOL kit, which very much changes low speed handling, and stall speed. That installation does not change the demonstrated crosswind capability value though, as no revised value is provided with the kit. (No Flight Manual Supplement or placard is provided, and that's the only way to convey changed information).

Manufacturer's and writers of design standards know that some pilots have more skill than others. They must account for the lowest common denominator of pilot skill sets in the standards. Hence demonstrating that the average skill set is enough to safely control the plane.

Sometimes when I have done modification design complaince evaluation flying for Transport Canada (I'm carefully not calling it test flying, Im not going to start that debate!) I wonder to myself if I am properly simulating average skill during cross wind work. If I apply a lot of effort to seeing what the aircraft can do, I may have gone beyond a demonstration of average skill.

Pilot DAR

[homeguard]

Look, this is all much simpler than is being argued.
The design approval of an aeroplane requires certain facts to be established. Hopefully someone will find the actual design regulations and link them here, it has been found before but some time ago.
The Demonstrated Crosswind Component is not an actual flown exercise but a mathmatical calculation based on designed control available. It is generally understood that this calculation demonstrates that an average pilot in reasonable practice should be able to control the aircraft safely when landing. The italics are not the regulation but how they might reasonably be interpreted. However these calculations are only one part of a scenario where many other factors may be dominent such as pilot ability and other considerations pertaining at the time. This is usually the case with light aircaft and therefore it would be impossible to define a limit. I'm sure that there are light aircraft with a crosswind defined limit, just the same.
A limit is normally applied to larger heavy aircraft (although not only) when beyond such a limit, control of the aircraft is unlikely irrespective of the pilots ability. This could be say a limit on the maximum angle of bank during landing owing to the fact that the wing tip, engine nacelle or propellor could strike the ground. There will be various reasons but i'm sure it is obvious that with the above restrictions the pilots choices are 'limited' and so therefore is the maximum crosswind.

[FullyFlapped]

DAR,

Is there an equivalent standard for "x-wind LIMIT" ?

I think you're missing the point. The definition of the word "demonstrated" is not the issue : what is being argued over is whether operating an aircraft beyond its demonstrated x-wind value is illegal by virtue of the fact that to do so instantly makes you a test-pilot and therefore invalidates your insurance (and makes your under-carriage fall off, evidently ...)

My argument is that if Mr. Cessna says that the MDCV "is not considered to be limiting", then he's saying that because his designers and test pilots have already proven this to be the case.

If I attempt to land with a ridiculous amount of x-wind and the wheels snap off, I'd expect to have a problem with my insurers. However, if the same thing happened a couple of knots over the MDCV, with the protection of that statement in my POH I'd be quite happy to pursue a claim.

In short, if they meant "limit", they'd say so ...

FF :ok:

[Fuji Abound]

DAR and FF

Actually FF I think it was a good post but for a different reason.

It brings home the key point on an interesting and very old debate.

For commercial ops it can be assumed that all pilots will perform to a given standard. In short a limit can be imposed because there is a reasonable possibility you will bend it if you go beyond the limit.

In GA the product liability lawyers learnt long ago that many of their customers really havent got a clue what they are doing. Consequently they are not going to tell you what the limit is, becasue many will try it and regret they did. However, what they will tell you is what a reasonably ham fisted pilot is likely to be able to get away with.

So as my final contribution on this one, I think how the number is derived is well known (to those on here at any rate), and I have seen absolutely nothing to convince me that it is in any way intended to be a limit.

(Sorry to disappoint you DFC - I respect the points you have made, I just dont agree with them)

[Tony Hirst]

Homeguard,
The Demonstrated Crosswind Component is not an actual flown exercise but a mathmatical calculation based on designed control available.
I disagree. My understanding is that the demonstrated crosswind is simply that which was observed by the certifying authority during flight testing for certification. I'm sure there are certain minimum crosswind capabilities that are mathematically built in at design time, like the FAA required 0.2Vso for example (something like that anyway). But I don't believe the demonstrated one is a limit unless somebody decides to make it so (A flying club's regulations for example). I certainly don't suggest anybody tries it, but I am sure I am not alone, I am sure there are many PA28 and C152 pilots out there who have landed in crosswinds several knots in excess of the demonstrated without any difficulties.

Now the PA17 on the other hand...well my limit is somewhat lower :\

[bookworm]

There is little mystery about how this number is determined:

AC23-8B FLIGHT TEST GUIDE FOR CERTIFICATION OF PART 23 AIRPLANES (http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgAdvisoryCircular.nsf/0/469cd77d24955f4e86256da60060c156/$FILE/Final-Part1.pdf).
107. SECTION 23.233 DIRECTIONAL STABILITY AND CONTROL.
a. Explanation.
(1) Crosswind. This regulation establishes the minimum value of crosswind that must be demonstrated. Since the minimum required value may be far less than the actual capability of the airplane, higher values may be tested at the option of the applicant. The highest 90-degree crosswind component tested satisfactorily should be put in the AFM as performance information. If a demonstrated crosswind is found limiting, it has to be introduced in Section 2 of the AFM.
...
b. Procedures.
(1) Crosswind.
(a) The airplane should be operated throughout its approved loading envelope at gradually increasing values of crosswind component until a crosswind equivalent to 0.2 VSO is reached. All approved takeoff and landing configurations should be evaluated. Higher crosswind values may be evaluated at the discretion of the test pilot for AFM inclusion.

It would be difficult to be more explicit about whether the vaalue is limiting or not, wouldn't it?

[The Flying Pram]

3.145 Directional stability and control
(a) There shall be no uncontrollable looping tendency in 90-degree cross winds up to a velocity equal to 0.2 Vs0 at any speed at which the aircraft may be expected to be operated upon the ground or water.
I don't want to argue the toss about the legality (or otherwise) of landing at above the "Demonstrated" figure, but the above value rather intrigues me. It appears to be very pessimistic even by the standards of "average" pilots.
In my machines case this is barely 5kts, and would hardly be noticeable. In practice (and backed up by some of the claims on here) a value of 0.3 - 0.4 would be more realistic. Or in the case of Chuck Ellsworth's Dakota 1.0!!
I really wonder if I shouldn't give up flying until such time as scientists can control the weather, or every airfield has multiple runways.

[Tony Hirst]

I understand that the 0.2Vso limit is only the minimum using only aerodynamic controls, I don't think this infers anything else.

Higher values maybe quoted if demonstrated. Where those higher values require the use of specific techniques, braking or engines to maintain control, those technique will be described in the flight manual.

[DFC]

Where in the flght manual does it say that you have to hold a licence to fly the aircraft?

For commercial ops it can be assumed that all pilots will perform to a given standard. In short a limit can be imposed because there is a reasonable possibility you will bend it if you go beyond the limit.

Indeed. And guess what the imposed crosswinf limit will be!!

bookworm has posted a very valuable quote;

The highest 90-degree crosswind component tested satisfactorily should be put in the AFM as performance information

This places it in the same category as airfield performance.

What will your insurance company say if you run into the hedge at the end of a 499m strip when the flight manual says you need 500m in the conditions?

Anyone who wants to use a crosswind higher than the manufacturer has demonstrated as being safe can do so any time they want. However, they simply have to be aware that if their insurance policy says no test flying then they are not covered.

They could always stand up in court after the accident and proudly tell the court that despite the damamged aircraft being evidence to the contrary, they are a pilot of above average ability........to the sound of "arrogant to$$3r" from everyone present. :E

----------

Pilot DAR,

design complaince evaluation flying

Love it, Must remember that in future. :ok:

Regards,

DFC

[Kirstey]

Is Beagle still about?
He IS a test pilot isn't he? sounds like a good source for an authroritive answer.
I've managed 28G38 at 80deg in a C150. With the instant wind at the top of that as I came over the threshold.
Piece of cake, and I'm sure no problem for the insurers if you come into difficulties..

[Contacttower]

This places it in the same category as airfield performance.


It may do but in reality take off performance data is not of the same nature as crosswind landing data...I remember reading an accident report ages ago which involved (I think) a King Air which crashed while landing in a crosswind that was higher than its demo limit. The accident report clearly stated that this did not constitute any breaking of regulations and that the wind was 'acceptable' to the crew because the aircraft had no absolute crosswind limit. Had the accident involved them landing on a runway which was too short for the book figures then the situation regarding the observation of aircraft performance data would have been rather different....

[Fuji Abound]

I said I wasnt going to post again - and it really really is my last, but I always worry about insurance issues.

Anyway I emailed my insurers to ask whether they would settle a claim if the aircraft landed in a cross wind more than the demonstrated cross wind component in the POH and in consequence was damaged.

They said they would.

In fact they have just 'phoned to say they wondered whether an accident had actually occurred. I told them it had not but thanked them for their concern. We chatted and I pointed them to this thread which he had actually been reading. He laughed, said so far as they were concerned the whole thing was totally ridiculous and they had all had a chuckle. He made one or two other amusing comments.

It has put my mind at rest so far as the insurance issue was concerned.

I appreciate other insureres may take a different view.

[FullyFlapped]

Bookworm :

It would be difficult to be more explicit about whether the vaalue is limiting or not, wouldn't it?

Absolutely.

Anyway, that's me out of this thread until/if Cessna reply to the letter I've sent. It's absolutely pointless trying to debate with someone like DFC who is willing to only quote the parts of a post which suit his purpose whilst ignoring the rest :-

If a demonstrated crosswind is found limiting, it has to be introduced in Section 2 of the AFM.
Mass weapons of destruction in 45 mins, anyone ? :=:yuk::ugh:

However, if anyone has any actual knowledge of any prosecution where a pilot has been done for exceeding a demo'd x-wind value - in an aircraft where the POH does NOT state the value to be limiting - I'd be interested in hearing it ?

Edited to add : Fuji, thanks for doing that. You will have set a lot of people's minds at rest - good for you !

FF :ok:

[sternone]

They said they would.......have just 'phoned to say they wondered whether an accident had actually occurred.

Did they phoned you to say it was ok, or did they emailed you back to say it's ok ? Just make sure you have a written proof :E

[Fuji Abound]

Sternone

Yep, been there, done that - all in writing of course.

Still, thanks for the reminder to everyone.

[Shunter]

Fuji, thanks for posting that which was what I was originally trying to get at. Mine have said the same, but as with many things in aviation the facts (as opposed to the folklore) appears to have got long since lost amongst the clubhouse bullsh!t, along with IMC-rating approach minima I presume...

[Pilot DAR]

DFC,

design complaince evaluation flying Love it, Must remember that in future. :ok:

-------

Yeah, I'm not quite sure what it takes to be proper in refering to one's self as a "test pilot", but I'm not there yet. I just fly the modified aircraft, evaluate the design change, and demonstrate that it still complies with the design requirements. If I like it, I recommend it for approval. It works though, all of my programs have been approved, with only one being reflown by a government test pilot as a double check...

Now, if I could get the pilots to actually read, and pay attention to the Flight Manual Supplements and limitation placards I issue for the mods....

Cheers, Pilot DAR

[IFMU]

All I can say is that you're a braver man than I...
Actually, I was just about scared to death. I was maybe a 30 or 40 hour student pilot on a cross country, Flew up to Great Barrington where it is a bit more hilly, and the weather there was a lot gustier and bumpier. I turned base and the turbulence turned me back on downwind. I ran out of aileron a few times in the turbulence. But close to the ground, the turbulence went away and it just resolved into the 20kt crosswind. I learned to fly on a n-s hardtop runway with prevailing westerly winds. So that part wasn't so bad. The left wing was mighty low. It was hard to taxi. But I was glad to be out of the airplane for a half hour. I never thought about just turning back and heading for home, partly because I was fixated on the solo x-c mission that I was there to perform. But mostly because I wanted out of the airplane for a little bit.

Since then I've got more experience under my belt. I would land a cub series aircraft in big crosswinds like that again. Usually the only time I seem to fly in those big winds are when I'm tugging gliders. If I didn't have a good reason I probably wouldn't go.

Crosswind is fun. It's all fun. That's why I fly.

-- IFMU