Menu Sign In Contact FAQ
Banner
Welcome to our forums

Landings at Megara LGMG limited to max demo crosswind in the POH

My aircraft has a fairly low demonstrated crosswind and I have landed in excess of this on occasion without issue. I don’t take it lightly but it would not stop me from making an approach and feeling it out.

I’d much rather the decision if you’re comfortable to land to be left to the pilot rather than someone pushing paper around. For me my own currency and comfort level is far more important in terms of what crosswind I’ll accept than the demonstrated figure.

LeSving wrote:

But, when it comes to cross wind landings everybody are all of a sudden expert test pilots showing the finger to the POH

You do understand that the max demonstrated x-wind figure in the POH does not mean that the test pilots have attempted takeoff/landing in stronger cross-wind and found that impossible or dangerous?

ESKC (Uppsala/Sundbro), Sweden

A pilot should always apply skill and judgement, however, landing at the demonstrated crosswind value should not be alarming, if the pilot is current on the type.

The whole requirement:

Sec. 23.233

Directional stability and control.

(a) There may be no uncontrollable ground or water looping tendency in 90 degree cross winds, up to a wind velocity of 0.2 VS0, at any speed at which the airplane may be expected to be operated on the ground or water.
(b) A landplane must be satisfactorily controllable, without exceptional piloting skill or alertness, in power-off landings at normal landing speed, without using brakes or engine power to maintain a straight path.
(c) The airplane must have adequate directional control during taxiing.Quote

Note the reference to “must be satisfactorily controllable, without exceptional piloting skill or alertness”. That’s exactly to assure that a pilot does not have to be a test pilot to safely land at the demonstrated value. A pilot who’s really current on the type could plan to land at a higher value. This is a judgement thing. If you can follow the centerline down final approach, it’s pretty likely that you can land safely in those conditions. If landing at the demonstrated value is challenging, perhaps some practice is in order. Certainly, when flying a type new to me, I’m not confident about my crosswind skills, I will go and practice. In every case, after a few landings, I’m feeling confident at the crosswind value for the type. In most cases, I have happily surprised myself, in that a higher value has not been a problem.

In one of my planes, which is a taildragger, crosswinds used to really worry me, so I practiced a lot. During that practice, I learned that I would prefer to land in a crosswind from the left, than into the wind, or no wind, it’s easier to land in the left crosswind. This confidence has come in handy a couple of times, when the choice upon arrival was to land crosswind, or to return to the point of departure, more than a hundred miles away, as there were no other runways to choose from nearer.

Like parallel parking, crosswind handling confidence comes with practice. A certified plane will not be approved if it’s crosswind handling is in question. I have tested some modified planes, which required aerodynamic “fixes” to demonstrate crosswind compliance. The certification process is at work here, it’s not a free for all – which is why I feel that the airport in question has taken a step too far…

Home runway, in central Ontario, Canada, Canada

My crosswind limit depends on my crosswind currency, and also the runway surface.
Bumps on a grass runway reduce the crosswind acceptable.

Maoraigh
EGPE, United Kingdom

Peter wrote:

The max demo crosswind number is even less relevant for departures, not least because, with a big runway, you can depart on a slight diagonal.

More to do with the airflow over the rudder is higher on takeoff (in conventional single) with the propeller slipstream giving much better rudder authority (hence why pilots who are unfortunate enough to ground loop a tailwheel plane tend to do it on landing not takeoff).

Angling across the runway unfortunately won’t do much (unless the crosswind is so strong and the runway wide enough that you can just take off across the width!) The crosswind reduction varies with the cosine of the offset angle you can use (where taking off exactly on runway heading would be a 0 degree offset). The cosine doesn’t change much until the angle starts getting above 30 degrees (e.g. if you angled 10 degrees across the runway, which is quite a lot, the crosswind component you have at the start of the takeoff roll would be 0.98 times the reported crosswind, so it’s not a reduction that’s going to be noticeable).

Last Edited by alioth at 20 Jan 10:08
Andreas IOM

A big issue is gusting or not. A steady wind is much easier to deal with than gusts. Another factor is the effect of terrain and changes on speed as you get closer to the ground. Higher winds amplify the variables…

Tököl LHTL

WhiskeyPapa wrote:

A big issue is gusting or not. A steady wind is much easier to deal with than gusts.

Also in gusts, the wind direction usually turns clockwise (in the Northern hemisphere) so it is better to have a gusty crosswind from the left than from the right.

ESKC (Uppsala/Sundbro), Sweden

alioth wrote:

The crosswind reduction varies with the cosine of the offset angle you can use

No. It varies with the difference of the respective cosines of:

  1. the angle between the wind and the runway
  2. the angle between the wind and your landing track = the angle between the wind and the runway + the offset angle you can use

The result can be very different from what you describe:

  • A pure crosswind behaves as you describe. On runway track, you get cos(0°)=100% of the wind as cross, on 10° offset, you get cos(10°)=98.48% of it.
  • A 45° wind gives you cos(45°)=70.71% of the wind as crosswind on runway track, but cos(55°)=57.35% on a 10° offset. That’s a 19% relative reduction (81% of 70.7% is 57.275%).
  • A 60° wind gives you cos(60°)=50% of it as crosswind on runway track. On a 10° offset, that’s down to cos(70°)=34.20%, that is a 31.6% relative reduction.
ELLX

LeSving wrote:

Hmm, people don’t trust their own abilities in making a dead stick landing and would rather pull the chute than glide down to a runway. But, when it comes to cross wind landings everybody are all of a sudden expert test pilots showing the finger to the POH

For me, a high-crosswind (significantly above POH value) landing, on the Cessna single-engine high-wing planes I have most experience with, is definitely much less an event (much easier) than a dead stick landing in benign conditions.

ELLX

You do understand that the max demonstrated x-wind figure in the POH does not mean that the test pilots have attempted takeoff/landing in stronger cross-wind and found that impossible or dangerous?

It means what it means. The aircraft behaves OK up to and including that figure, period. Above that value, you have to figure it out yourself. It may fly just OK, or it may not. It may require extraordinary skills, or it may not. There is no knowing exactly at what point the aircraft becomes uncontrollable, or why.

Flying with a cross wind component exceeding the demonstrated value, and you are in fact a test pilot. It’s fully legal, but you are flying the aircraft outside chartered waters nonetheless.

Nothing wrong with that, only funny looking at the other thread where people suddenly find it “dangerous” to do a dead stick landing, which is fully charted and a requirement for any PPL license.

The elephant is the circulation
ENVA ENOP ENMO, Norway
Sign in to add your message

Back to Top