Max. Demonstrated Crosswind Compoent

[MSU Flyguy]

What is everyone's opinion on the maximum demonstrated crosswind component, limitation or recommendation?

 

[CrewDawg]

I would say recommendation, just depends on how comfortable you are with the aircraft. I would try to stick as close to that number as possible though.

 

[pilotman2105]

maximum demonstrated crosswind component

It is just what it says it is. The maximum crosswind component that was DEMONSTRATED during flight testing/certification (or some other similar phase).

It's just a recommendation.

 

[midlifeflyer]

If it doesn't show up in the "limitations" section of the POH, it's not a limitation.

(The appearance of an informational placard in the limitations section is a requirement that the placard appear, not necessarily that the information in the placard is a limitation)

 

[Lead Sled]

What is everyone's opinion on the maximum demonstrated crosswind component, limitation or recommendation?

Opinion? I don't mean to be a pain, but on things like this opinions have nothing to do with it. It is what it is. Simply put, the maximum demonstrated crosswind component is nothing more than a weather report. That's how strong the wind happened to be blowing on the day that they happened to be doing the crosswind certification tests.

 

[Ralgha]

Yeah if we followed that demonstrated crosswind limit, we wouldn't have flown at all last summer since our crosswind runway was closed for most of it.

 

[midlifeflyer]

Re: Re: Max. Demonstrated Crosswind Comp

That's how strong the wind happened to be blowing on the day that they happened to be doing the crosswind certification tests.

In reality, it's probably more like

They waited until a day when a wind with the crosswind component they wanted to put in the POH happened to be blowing.

 

[Lead Sled]

Re: Re: Re: Max. Demonstrated Crosswind Comp

In reality, it's probably more like
They waited until a day when a wind with the crosswind component they wanted to put in the POH happened to be blowing.

Mark...
You give those guys more credit than they deserve. When it comes to flight test schedules you usually have to take what you get.

Lead Sled

 

[JediNein]

Max demonstrated crosswind? It's a goal not a limit!

Keep in mind the maximum demonstrated crosswind component was that wind where the test pilot gave up.

It took a direct 30 knot (gusting to something in the 35+ range) crosswind component for one of my students to figure out how to keep the nose of the airplane straight on final.

The tower was ready to roll the crash trucks after our first request for the runway with the worst crosswind. He probably had half of SoCal plugged in placing bets by our third approach. The fifth approach he'd caught on, we wanted to fly down the runway, not land, and definitely weren't stopping.

On the tenth approach, the student touched down at last, and promptly headed for the side of the runway.

On the twelfth approach, the student touched down and kept the plane on the centerline for a few hundred feet, then lifted off again without letting the wind snatch the controls.

On the way back we discussed how much the wife and kids would be bugging him to sell his newly aquired airplane after a flight that ended in a turbulent approach and landing at even half of the winds we had encountered.

On landing at the home airport, we encountered a 5 knot direct crosswind component. He handled it just fine.

Fly SAFE!

 

[midlifeflyer]

Re: Re: Re: Re: Max. Demonstrated Crossw

You give those guys more credit than they deserve. When it comes to flight test schedules you usually have to take what you get.

The consistency of 15 -20 among so many light airplanes and the lack of airplanes with maximum demonstrated crosswind components of 13 or 8 or 3 suggests to me that there is some target in mind.

Waiting to meet it isn't a big deal unless you're assuming that of the many many test flights taking place during the certification process there is only one "crosswind test day".

 

[Lead Sled]

Re: Re: Re: Re: Re: Max. Demonstrated Crossw

The consistency of 15 -20 among so many light airplanes and the lack of airplanes with maximum demonstrated crosswind components of 13 or 8 or 3 suggests to me that there is some target in mind.

I would think that the reason that most speeds, weight, and all other performance numbers competitive is that most design parameters are the same or nearly so.

Additionally, most manufacturers will occassionally limit the max demonstrated X-wind speed so as not to give "those less than proficient" among us a false idea.

I've got a buddy in flight test. When the schedule calls of x-wind testing they do it. They take what they get - as long as it is reasonable.

Lead Sled

 

[CDVdriver]

max.DEMONSTRATED xwind

Like it says, a test pilot has safely landed the plane in a crosswind this strong or it's an interpolated number.
BIG thing to remember (like I tell my students) he's a test pilot you're not, now you figure out if we can do this or not.
The ones that think they can are always in for a good laugh..

 

[AcroTim]

Not a limitation

As a matter of fact some POH's or AFM's list the demonstrated crosswind component in the normal section, no in the limitations.

 

[midlifeflyer]

Re: Not a limitation

As a matter of fact some POH's or AFM's list the demonstrated crosswind component in the normal section, no in the limitations.

I think that just about all do that. The only cases I can recall where it was in limitations were

a. the airplane actually has a max crosswind limitation rather than a maximum demonstrated crosswind component

or

b. the airplane has a limitation that requires that a palard be posted advising of the max demonstrated crosswind component. In that case, the placing of the placard is the limitation, not what the placard says

 

[Crizz]

The limit would be your ability as a pilot.

 

[Vortilon]

While we all recognize it is not a published limitation, if you had an incident while exceeding this "manufacturer's advisory" you could certainly be held responsible for disregarding safe & accepted practices and disregarding information from the manufacturer. Of course as a PIC you are always responsible for everything and you always have to balance risk but sometimes its good to put yourself on the business end of an inquiry board and pretend you are explaining your logic to a FAA Inspecor & their lawyers. Maybe there you'll find your answer.

Be careful out there!

 

[standaman]

I agree with Vortilon. Any lawyer worth a salt would paint you as exceeding a manufacturers recomendation. The FAA could always come after you for careless and reckless operations from what I know is very very broad.

 

[Lead Sled]

I agree with Vortilon. Any lawyer worth a salt would paint you as exceeding a manufacturers recomendation. The FAA could always come after you for careless and reckless operations from what I know is very very broad.

I disagree. Remember, it is not a limitation or a recomendation. It is simply the amount of crosswind that was demonstrated on "crosswind landings day" when they were flying the certification flights. Like I said in my first post, it is basically a weather report - we now know how hard the wind was blowing on that particular day.

Just for grins, I pulled out my G-100, Astra SPX and Astra FlightSafety Manuals. Guess what? There is no mention of demonstrated crosswind in the AFM. My G-200 manuals are packed away, but I would venture a guess that there is no mention of it there either. In fact, I don't remember a number even being mentioned in the Lears, but is't been 8 years since I've flown one. I guess that this means that we can't land in a crosswind with out being in danger of incurring the wrath of the FAA.

Lead Sled

 

[bugchaser]

All I know is that if we didn't fly when the wind exceeded the max demonstrated x-wind, we would never get anything done. When it gets up to about 40kts we start to think about it.

 

[Jmmccutc]

the worst is a statement in my school's SOP's, stating that, "...no student shall take off or land when the X-wind exceede that demonstrated by the manufacturer..." seems like we never get anything done if there is so much as a light breeze...Crewdawg, am i right?

 

[igneousy2]

I agree with Vortilon. Any lawyer worth a salt would paint you as exceeding a manufacturers recomendation. The FAA could always come after you for careless and reckless operations from what I know is very very broad.

If you end up in the weeds on the side of the runway, it doesn't matter what the wind was or what the x-wind component of the plane was you are toast. You're either wreckless if you landed with winds in excess of the x-wind component or you're an incompotent pilot if you could not handle the plane in a x-wind below the max-demonstrated.

Either way...you loose.

Later

 

[spngbobsqrpilot]

Max Demonstrated X-Wind

The "limitation" (not actually a limit) is derived by a function of 20% of the stall speed of the aircraft being certified. (Can't remember if its Vso or Vs. as it has been a few years since I have taught primary students X-wind landings.

The FARs (Part 25, I believe) require the aircraft being certified to be capable of controllabilty with a direct x-wind component equalling that speed above. That is all. This is the Maximum demonstrated X-wind and the actual wind on the date of test flight may have been greater, however, the number in the manual is the demonstrated capability to show certification according to Part 25.

A manufacturer is not required to show the actual crosswind encountered during the flight testing phase (and may be opening itself up to lawsuits if a number is placed there showing what a qualified test pilot can do rather than a novice can if the novice attempts to use that number as a personal limitation) and that is why, with experience, it is possible to land your C-152 in crosswinds of 30 kts. No, the manufacturer won't tell you this in your manual because it was not required for the manufacturer to do so.

 

[midlifeflyer]

The "limitation" (not actually a limit) is derived by a function of 20% of the stall speed of the aircraft being certified. (Can't remember if its Vso or Vs. as it has been a few years since I have taught primary students X-wind landings.

It's Vs0.

Which Part depends on the aircraft certification. For us little guys, it's in Part 23

==============================
§ 23.233 Directional stability and control.
(a) A 90 degree cross-component of wind velocity, demonstrated to be safe for taxiing, takeoff, and landing must be established and must be not less than 0.2 VS0.
==============================
But that only establishes a minimum certification safety standard. It doesn't mean that's the number that's used for the published demonstrated crosswind component. After all, the company gets a competitive advantage by showing how much "better" it's airplanes are, without going overboard.

For example, Vs0 in a new 172 is 47 KCAS; in a new Archer III it's 45, but neither manufacturer publishes 9.4 or 9 KTS as the max demonstrated crosswind component. In fact, Piper, with the lower Vs publishes a higher demonstrated crosswind number (17 KTS) than Cessna (15 KTS).

 

[GVFlyer]

X winds

When we were doing GV developmental test and certification we dedicated a test article to crosswind testing for several weeks. Part 25 calls for a minimum of 20 knots, but demonstrated crosswind does not have to exceed 25 knots. We were flying all over the country looking for crosswinds. When we found 28 knots we thought that was good enough.

For T category aircraft most test programs are around 18 months long and take about 1500 to 1800 hours to complete. Note I said most - several exceptions come to mind. We do have a schedule to maintain as someone suggested, so when we get a good number we move on.

The exception was the Air Force C-20B (G-III). They wanted a greater cross wind capability so they paid Gulfstream to retest the jet and come up with a procedure to accomodate better numbers. We were able to give them 35 knots with 8 degrees wing down and up to 4 degrees crab at touchdown.

In my view, when you exceed the demonstrated crosswind for your aircraft you are venturing into the realm of the experimental test pilot. We do a safety review board prior to such testing, limit the occupants to mission essential crew and don't carry passengers.

GV

 

[Muddauber]

Now that makes sense...

 

[standaman]

I agree with gvflyer. We should not debate the merits of limitation versus suggestion versus are we really breaking the rules in the first place. The question should be is it at all smart under any circumstance. Smarter people than myself developed the max crosswind component. Have I exceeded it, probably, should I exceed it, I don't think so. As a flight instructor should I teach my students to explore these flight regions which manufacturers test pilots have not even gone. My answer to this is no. It sets a bad precedent for students wether it is legally okay or not.