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A-3TWENTY
20th Feb 2010, 14:24
Hi all ,

Acording to FCOM 3.01 , max. demonstrated is 38 kts including gusts.

I f you go to FCOM 2.04.10 Pag 11, they say 29 Tk off and 33 LDG for dry and wet runways witth braking action good.

Since we have a discrepancy in these two manuals , I consider the more restrictive one as a limitation,i.e, FCOM 2.04.10

What you guys think about the note below the table at FCOM 2.04.10 ?

"Note:
The maximum crosswinds values given in the above table are recommendd values based on computations.They are given without gust. "

So , my doubt is:

1.Are these values limitating?

2."They are given without gust" means that they include gusts?
Or Can I land with a wind of 33 Kts gusting 45?

Thanks in advance for your opinion,

A-3TWENTY

Airbus_a321
20th Feb 2010, 14:49
limitating - no.
they state clearly: demonstrated and recommended. So its your baby!
know about not too bad landings done in wind conditions, exceeding those demonstrated and recommended "limits"

If you make it, o.k.. If you dont make it well and you have a non-aviation bean-counter as boss, one of those who dont have any clue about real flying (and there will be a lot), guess you will get some coffee and cookies therafter in his office.

backofthedrag
20th Feb 2010, 15:03
Page 11 of 2.04.10 ( REV 41 ) refers to contaminated runways and in my version the Braking Action Good for WET runways ( NOT DRY ) crosswind limit is 29 knots for T/O and 33 for landing.

The 38 knots in the Limitations section applies to all cases including dry runway.

As to gusts , I believe the 38 knots includes gusts , but the smaller values are computed without gusts . As already pointed out , it is up to you to interpret this as you wish , and defend yourself subsequently.

Apologies if I have picked up an out-of-date version and I stand to be corrected , as usual.

PantLoad
20th Feb 2010, 17:39
Check out FOB "Crosswind Landings"

Max recommended bank angle at touchdown is 5 degrees.
Max recommended crab at touchdown is 5 degrees.

So, according to the FOB, that equates to about a 30 kt crosswind.

What about a 38 kt crosswind? HaHaa HaHaa

Fly safe,

PantLoad

A-3TWENTY
20th Feb 2010, 17:40
Hi Folks ,

I didn`t express myself well. When I say Limit , I say that because for me demonstrated and recomended it`s the same of a limit.I am not a test pilot so I don`t consider a landing above the demonstrated or recommended limits.

So what I meant in this case since these values are limiting for me , which values do you take in consideration when landing in crosswind conditions?

Take in consideration, that the values presented in the FCOM 2.02.10 for good conditions are to be considered for dry and wet runways.(Which contradicts FCOM 3.01).

About the note, you guys which have the english as a native language...When they write ".They are given without gust" . What do you all think about?
Are the 33 including gusts? Or I can land with 33 gusting 55kts?

Thanks All

stansdead
20th Feb 2010, 17:43
In my company we are limited to 29 KT across INCLUDING GUST.....:eek:

Still, that's the way it is here. Doesn't bother me. It makes life very easy.

A-3TWENTY
21st Feb 2010, 18:45
I`ve just discovered that the same aplies for the A 330/A340

rudderrudderrat
21st Feb 2010, 22:48
Hi A-3TWENTY,

According to our manuals - provided the braking action is good, then the runway can be dry / damp / or wet (<3mm) and the maximum crosswind for landing is 33 Kts gusting 38 kts.

In the Northern Hemisphere, I prefer a cross wind from the Left in gusty conditions.

safetypee
22nd Feb 2010, 19:12
The maximum advisory (demonstrated) crosswind value should be used with caution. A truly limiting crosswind value would be in the AFM limitations section, but even this might require qualification.
Max demonstrated (and limit) values provide the best advice based on the manufacturers tests; but only the crew can apply this advice to a given situation.
Thus, crews need some understanding of how the values are obtained, and greater understanding of the conditions which can affect how the value should be used.

Manufacturers usually have high accuracy measurements for the wind; these are rarely available in normal operations. If ATC reports gusts there may be few indications of a direction change and perhaps none for the duration of the gust. Pilots require gust direction, magnitude, and duration for a complete understanding.
Flight tests may be conducted on a range of runway surfaces, but these are rarely stated in the manuals. Thus, there could be a considerable difference in crosswind capability on a wet grooved or high friction course surface, and on an un-grooved wet concrete runway; the latter can be very unforgiving. Crosswind landings aren’t just about aligning with the runway, they include staying on the runway.

Similarly how wet is wet. Reported good braking in wet conditions is more often associated with ‘light rain’ and/or good drainage, thus in moderate or heavy rain, or even light rain with poorly drained runway, the braking performance could be distinctly ‘poor’ and thus reduced lateral control. There is no sharp transition between wet runway and a flooded / contaminated runway (3 mm). Thus anything between wet (25 kts xwnd) and contaminated (5 kts xwnd) has to be judged and carefully considered together with the runway surface and wind measurement factors, - note that the manufacturer might not have tested these combinations and only used computer models.
Also, consider how the braking action is reported. Other pilots using thrust reverse, and/or autobrake on a ‘poor’ runway may provide an unrealistically optimistic assessment.

Manufacturers’ limits and advice should be based on the skills of an ‘average’ pilot; however due to the difficulty in judging a world-wide ‘average’, workload is often used in the assessment – tolerably low workload. Occasionally, in addition to the max demonstrated value further guidance (lesser values) may be provided for a range of situations; these values may also be based on simulations.
Thus judgement of the level and currency of skill required for a crosswind landing remains with the operator or more often the Captain. A human weakness is a tendency to judge capability as being better than it really is, so some safety margin should be provided in the judgement. Consider how often crosswind landings are practiced, what maximum value has been experienced recently (and what were the conditions), and has the limiting condition ever been flown ‘for real’.
Also, consider that for most other limit ‘speed’ situations, aircraft certification provides a safety margin – stall margin, Vmo over speed, flap / gear limits, which can accommodate operating error. No margins are required when certificating crosswinds, yet these situations involve many opportunities for error.

Thus a safety margin should be added to the crosswind wind ‘limit’, gusts and turbulence should be considered seriously, and as being within the limit even if not published. Start with the lower values.

rudderrudderrat
22nd Feb 2010, 21:20
Hi safetypee,

Sound advice.

We should realise that "demonstrated" crosswinds are chosen to look good in the "sales brochure".

A-3TWENTY
24th Feb 2010, 08:17
Hi rudderrudderrat,

But if we can relate the tables of fcom 2 with fcom 3. (As you said ldg33 gusts 38) for dry , damp and wet rwys , so we can do it for the other values as well , can`t we?

I`d like also put the question in another way.Decision Making. No more concepts.

1. You are approaching for a wet runway and at some point the tower gives you a wind of 240/36 Kts.Crosswind. Do you proceed?

2.You are approaching for a wet runway and at some point the tower gives you a wind of 240/30 G38 Kts.Crosswind. Do you proceed?


A-3TWENTY

rudderrudderrat
24th Feb 2010, 09:42
Hi A-3Twenty.

Lets assume the runway is 33 and the braking action is reported as good.

1) 240/36 is outside my limits so divert.

2) 240/30 is within limits so continue the approach. If I get a gust of 38 kts which becomes uncomfortable to handle - then GA and do a DODAR in the hold. During a gust, the wind should become more geostrophic. If I'm in the Northern hemisphere, it will come from say 270 degs. If it is still comfortable to handle, then continue whilst it feels OK, being ready to GA at any time before selecting reverse. Once Rev selected - continue the roll out.