Demonstrated X wind a pointless figure ?

[Pace]

If you cannot hold the runway centerline during final approach, completing the landing may be difficult.

Surely that is a more accurate way of deterring the crosswind limit and adding a safety buffer between that maximum ?

I still am not convinced that demonstrated has any meaningful relevance to what an aircraft and pilot can handle and it seems to be very un scientific and out of the hat

Pace

[Pilot DAR]

Surely that is a more accurate way of deterring the crosswind limit and adding a safety buffer between that maximum ?

The "accuracy" during crosswind certification flight testing I have done, was the authority's insistence on really precise wind speed measurement at the time I flew the tests. Otherwise, it was simply could I do it, or not?

The most extreme crosswind test I have flown were both in Cessna Caravans. Happily, I well met the standard of "average skill" as I had less than 50 hours total time on Caravans for both test, so I could hardly be called "skilled" on type. One test was 38G45 knots, 40 degrees off the runway heading - which is "off the [Cessna] chart" for the Caravan. It seems to equate to about 32 knots direct crosswind, if I extrapolate Cessna's chart. This was coupled with the requirement that I fly full stall landings and takeoffs (tailstrike tests). There was a lot of chirping of wheels during that testing! I did reach and hold full pedal several times, so I knew I was close to the "limit" of my skill.

That made the subsequent test at 19G25 direct crosswind seem easier, but there was a huge keel affect change mod on the plane, and a snow covered runway, so wheels sliding was a concern.

In those conditions, my limited type skill told me not to apply lots of reverse, as that tends to blanket the rudder with turbulent air, which you really need to be working for you to as slow as possible!

Other types I have flown crosswind tests have given me to understand that by applying one's self, the "demonstrated" value should be manageable. I have certainly never thought to myself "wow, that would be hard to do!"

[pattern_is_full]

There was a lot of chirping of wheels during that testing!

An aside - I am generally a low-wing fan. But I have to tip my hat to Cessna's spring-steel struts for handling side loads. My sole serious experience of wind shear was a gusty day when, right in the flare, the 25-kt wind swung around from a 15° right headwind to a 100° tail-xwind in about 2 seconds. Power and rudder kept me out of the grass and runway lights, but I still touched down with quite a side drift. Heavy thump and screeching, but those angled C172 struts toughed it out.

Back to our regular scheduled programming...

[Genghis the Engineer]

Originally Posted by Pace

Surely that is a more accurate way of deterring the crosswind limit and adding a safety buffer between that maximum ?

I still am not convinced that demonstrated has any meaningful relevance to what an aircraft and pilot can handle and it seems to be very un scientific and out of the hat

Pace

I think that you're right Pace to be honest - and I've flown several crosswind trials, and written or signed off several more POHs.

The way it's done has some value - a figure has been determined - through a combination of opportunity and requirement (basically it was the best the TPs could get in the time and locations available, but they were required to at least hit 0.2Vso - which for a part 23 single means 12 knots or greater - less for microlights and part VLA aeroplanes.

The requirement to evaluate against "typical" piloting ability is minimal - although tools to do so certainly exist: the Cooper-Harper Scale being the most immediately obvious, and the requirement to provide much meaningful handling advice in the POH is also minimal.

A few lines of informed narrative would be much better, viz...

"During flight trials, the aeroplane was tested on both take-off and landing up to 20kts crosswind from the right, and up to 15kts from the left. The preferred landing method was the wing-down method. The aircraft was fully controllable up to those values without requirements for advanced piloting skill, with up to half control deflection being used. It is likely that an experienced pilot on type will be able to handle greater crosswind values, but no guarantee of this is provided."

Or something like that.

Undercarriage strength *should* be a bit of a red herring incidentally, as any correctly flown technique should result in the aeroplane tracking straight down the runway at touchdown, not skidding sideways.

Unless it's one of those rare aeroplanes designed to be landed crabbed - I can only think of one of those on the UK GA fleet, and there aren't many HM1000s flying nowadays, so that's a pretty obscure case.

G

[ChickenHouse]

Just one last remark and example citation, go to official Cessna 172H POH , Section II, page 2-12, read "The maximum allowable crosswind velocity is dependent upon pilot capability rather than airplane limitations. With average pilot technique, direct crosswinds of 15 MPH can be handled with safety." I am sick and tired of idiots such as Genghis, so this is the last time I read or post here in pprune, have a nice life.

[foxmoth]

Toys being thrown out of the pram there! But then this is the guy who started a thread giving details of students behaviour then complained because we were commenting on it without enough info!

[tb10er]

Demonstrated x wind landing

If you bend your beloved aircraft and the cross wind is beyond that demonstrated in the PoH, do you think the insurance company will pay out without lots of questions?

[Pace]

TB10ER

As it is a fairly meaningless figure as a demonstrated number not a limiting number I would think that it would be hard to refuse a claim on demonstrated alone.

There are many factors which can lead to loss of control, how steady the wind is ? what the gust factor is, Windshear, pilot ability etc.

Even down to how slow the pilot gets? Rudder authority is relative to airflow as we know in VMC demonstration in twins.

More airflow more authority.

That brings in the consideration in very strong crosswind components of carrying higher speed and flying it on rather than stalling onto the runway. Obviously runway length and headwind component coming into the equation

Pace

[9 lives]

In the case of "demonstrated" it is a hint, in case of "max certified" it is a setting for allowed POH operational limits. In first case and an incident you underestimated your skills, a mistake, in second case you violated operational limits. And be asured, a 1955 C172 will be case 1, while an after1986 C172 may be case 2.

This statement (and kind of thinking) muddies the waters needlessly, and is not a good basis for pilot decision making. The phraseology of flight manuals was standardized in the mid '70's, and "demonstrated crosswind" was on of the elements captured in that. As can be plainly seen from the POH wording presented by Chicken House, the referenced POH specifically states that the crosswind value is "rather than airplane limitations." not limiting - it's not stated in the limitations section as a limitation. It's a value demonstrating the aircraft's capability.

I cannot speak as an insurer, but I would not accept denial of a claim for a crash when no limitation was exceeded, and the aircraft was being flown with good airmanship. I agree, that there comes a point where an attempt at a crosswind is too much, and that would be poor airmanship in attempting it. I think insurers sometime even pay out for poor airmanship, but I've never tried....

[Pace]

ChickenHouse

We all get it wrong sometimes and I for one would feel sorry if you went

I seriously listen to Genghis and Pilot Dar and others here. Many have a huge amount of knowledge far exceeding my own.

I know who they are and listen to what they have to say.

To throw your Dolly out of the pram is silly as if I had done the same where I have posted mistakes I would have long gone

Pace

[Jan Olieslagers]

I am sick and tired of idiots such as Genghis

I for one would miss GtE a thousand times worse than I would miss you. I you must go, bye bye! But a more positive plan B might be conceivable.

[Jonzarno]

I agree! Having shared a flight with GTE and spent a good bit of time talking about flying with him, I'd fly with him again any day

[Mach Jump]

Chickenhouse:

Am I missing something here? Maybe a post has been deleted?

Why are you having a go at Genghis???

I've just scrolled back through the posts, and I cant find anything that Genghis has said that isn't perfectly logical and helpful.

Please help me understand what happened here.


MJ

[Pilot DAR]

No posts have been deleted from this thread.

[jjoe]

Post 1- OP?

Is there any practical value to a demonstrated X wind figure or is it only of value to novice pilots ?

Lots of good (and terrible) debate?/responses elicited IMO.

I'm no linguist or philosopher or gynaecologist.... but I'll have a go!
(Yes, it's THAT late ,Blue Nun late, and surely shaggy must be asleep by now!)

The two parts of the question are not mutually exclusive i.e. there is no need for the 'or'. The answer, arguably, is 'yes' to both parts by definition.

Why? Well, it tells you that it (demonstrated X wind figure) has been successfully and 'comfortably'* carried out before at that level- that's practical; fact not degree.
In this narrow definition, then, any pilot who has not exceeded it must be a novice; fact not degree.

Tin hat on.

I'm not sure whether English is Chickenhouse's first language.
English comprehension certainly isn't.

English is a language, first or otherwise. English comprehension (certainly) isn't!

for all CH's faults, and I have derided him previously for his inability to make his point in 'proper' English and other things, in this case I do think he has made a point and proved it- however cack-handedly and his 'throwing toys out the pram' and other similar responses are unwarranted as I think he genuinely is trying to help.

Genghis is definitely not an 'idiot' and I think CH just lacks the vocabulary to put his point across. I also don't feel CH is deliberately playing stupid games.

Chickenhouse, don't leave, make your point clearer!

However, good question.

Anyway , if the POH told you everything, why would you need an instructor?

[9 lives]

in this case I do think he has made a point and proved it- ...... as I think he genuinely is trying to help.

Opening my mind, what point has CH made? I don't follow? Perhaps wrongly, I understood the point which CH has tried to make as being that pilots are "bound" by a "limit" for the operation of the aircraft (a 172, of varied vintage, in this case) in a crosswind, by wording in the POH/Flight Manual. That wording has a literal, and regulatorily intended meaning, is other than what CH has advanced.

I think CH just lacks the vocabulary to put his point across. I also don't feel CH is deliberately playing stupid games.

English as a second language issues aside for the moment, it is the responsibility of those of us in aviation to understand the application of English in the intent of how the POH is to be interpreted, when using an English version. Agreed, pre mid '70's, the format of POHs was not harmonized - but it was not terribly different, just a little scattered by comparision. However, since then, the format and terminology is very consistent, and one of the roles of an instructor is to assure that the candidate understands how to use and interpret the information in a Flight Manual - at least a post '70's format edition.

If a poster here would like to be given a bit of grace with their use of English, that is fair. This is a great venue for practicing English, in an aviation environment. However, If a poster, who for whatever reason is not communicating entirely clearly, advances very specific thoughts which are dependent upon a precise use of English, they should not be surprised that other posters may see it differently, and challenge their assertion. I can assure the audience from my first hand knowledge that GtE has an outstanding command of English, and aviation. Challenge him only with a willingness to learn yourself!

Anyway , if the POH told you everything, why would you need an instructor?

I interpret this as humour. But for those who might doubt, be reminded that reading and understanding a Flight Manual is very important, but it is a fraction of what a pilot needs to know to fly a plane! It only presents information specific to that plane. I think Cessna is aware of this, when they write, as the second paragraph in in the introduction section:

"This handbook in not intended to be a guide for basic flight instruction or a training manual and should not be used as one. It is not a subsitute for adequate and competent flight instruction............."

But, I expect that everyone here has a command of English, and has read the flight manual to know that already!

[Pace]

Everyone has a contribution to make and even the best make mistakes in something they say.

Not everything posted in these forums is fact some doesn't really matter other mistakes can be dangerous if taken as fact by other pilots especially the more novice.

That is the dilemma as if the more knowledgeable note that mistake and rectify it there is always the risk of hurt egos, retaliation and defensiveness which can quickly all become very personal.

On the internet we often do not know who we are talking to, who they are or what their credentials are.

I used to be involved in home flight simulators and some development of third party add ons.

Like in real world flying forums there were active forums which were also anonymous and you really did not know who you were talking too.

I remember only too well one poster who posted under the guise of being a 747 Captain and did so for some time . He wrote with authority and to be honest added a lot to the forums with the mass of technical detail he contributed until one day there was a glaring mistake which got us all thinking that no way was this guy even a pilot.

He turned out to be a 12 year old kid who adored the adoration his guise created and he was a master at googling and adapting information he googled to appear like his own writing.

Ok he was found out but did he contribute? Yes he did as he put so much work into keeping that guise going and actually added a lot of technical information to many in the process.

I am not for one minute putting CH in that category but pointing out that we all have a contribution whatever our real life backgrounds and its a shame if anyone leaves because of a damaged ego or many of us would have gone a long time ago me included We all probably know who the real deals are the ones to listen too and they in turn have a duty to correct inaccurate information especially stuff which could be dangerous

Pace

[Pilot DAR]

Great post Pace, I heartily agree. It is an unfortunate element that "credentials" of posters can be very difficult to verify, but that is the entitlement of privacy. It is nice the people want to contribute, but sometimes what that person has to offer is more "I think I heard someone I did not know say this once", which may have very little authority. It's nice to see either direct quotes of authoritative information, which is traceable, should someone wish to, or links or references which can be verified.

In this thread, several posters did present a link to support what they are saying. This is very useful, as it informs us all of the fact or background of the topic, and from that we all learn. Further to that, the presentation of fact, which is independently authoritative, removes the need for the poster themselves to have credibility.

One of the more "in your face" aspects of this I have seen, are those stand around discussions which occur in a group of pilots, where expertise about certain aircraft types will begin to flow. Sometimes the topic will involve an aircraft type with which I have familiarity. When I hear mis-information, I like to engage eager speakers by engagingly asking them to tell me about their experiences in flying that type. Too often, I hear back "well... I've never actually flown one...". Okay, now I know the level of authority I should place in that person's opinion of that specific topic.

Here, we welcome pleasant, informative discussion. Learning, and disseminating wisdom are great, when we can do it. Participate at the level you fell comfortable with, but if you are not "authoritative" (and I'm not directing that at anyone, just a general thought), feel free to say "I've never flown one, but...", or, "I'm not an instructor, but...." Etc. And go on with your thought or question, I'm sure everyone here would like you to have the best responses.

It is a certainty that no pilot can have "all the experience", so it is entirely possible that an experienced pilot here, could still have a rather basic question, or mistaken thought on another area of piloting. For example, a poster in this thread I believe flies jets. I never have flown a jet. If that poster speaks jet, I will listen, and perhaps ask for clarification, before I make an error which would show everyone how little I now about flying a jet!

This forum is frequented by some aviators of awesome credential, who, if they were charging for the wisdom they offer here, would be charging by the hour many times what an instructor would charge. I know this, because I have personally met a number of these frequent, and much appreciated posters, and learned a lot from them myself.

Ultimately, it is up to you, the reader, to think about what you read here, and do your own research to verify it, and thus add it to your knowledge. If you feel that you cannot publicly verify it, then PM the person - politely please, and ask for clarification. If your motives of learning ore genuine, I'm sure their reply will be too....

[flybymike]

English is a language, first or otherwise. English comprehension (certainly) isn't!

Point of pedantry accepted.
Perhaps "Comprehensible English" might have been a better choice of words!

[S-Works]

I am sick and tired of idiots such as Genghis, so this is the last time I read or post here in PPRuNe, have a nice life.

Chickenhouse, whilst Ghengis can be an annoying tit at times and on occasion does post on Instructional matters with the same authority you seem to have taken up on aircraft engineering I can assure you that when it comes to a pissing contest on such matters you are not even qualified to get into the ring with him.

So perhaps relax a bit and learn from him?