Wind GUSTS

[LEM]

When making decisions regarding maximum wind limits, e.g. max tailwind for takeoff, I had always assumed what is officially limiting is the steady wind, and the gust is left to the Captain's discretion.

Now somebody pipes up that the gust is officially limiting too....

I'd like to know if this matter is left to the various company standards (if any...), or if the Manufacturers solve this doubt somewhere (the 737 manuals don't help much...)

Thank you :confused:

[bafanguy]

My USA company performance calculations were based on max gust velocity and least favorable direction when computing x-wind, tailwind, etc. Don't know if this was mandated by a manufacturer or company policy...suspect company policy. The old" prepare for the worst and hope for the best " thing, I guess.

[Idunno]

In my book you have to consider the gust velocity.
Anything else and you're just kidding yourself.
They'll hang you when you go off the runway (if you live).

[fireflybob]

Interesting question - another aspect is what is the definition of a gust? When I looked this up a while ago in the UK it was a change in windspeed of 10 kts or more from the mean speed.

Crosswind components are not factored so the most pessimistic figures should be considered (ie max angle off runway and max gust etc) although that said wind checks on final approach tend to be instantaneous but there can be a big difference between tower reported wind and what its actually doing at touchdown or on the runway.

As far as performance is concerned remember that headwinds are factored 50% and tailwinds 150% but calm is not factored at all - important to remember if you have assumed calm for perf calcs and there is actually a light tailwind.

Hope this helps

[80/20]

Aircraft manufacturers and many aviation book publishers are basing their recommended takeoff and approach speed/performance/wind calculations on official documents for pilot training, aircraft certification, AOC approval and pilot examiner handbooks.

In short the “Boeing version” is representative for these documents.

ATIS/METAR gusts are also defined by official documents, eg. ICAO

[DanAir1-11]

In the 'good old days' we used to look at a snapshot of recorded gusts 1 hr prior to time off gate and examine the trend, if decreasing over the hour , we'd use the highest reading, however if increasing we's factor it up by 5%. (simplified, as obviously other factors are considered, but that's the guts (or should that be gust?!) of it

Not foolproof by any means, but better than suck it and see.

Regards

[L337]

As far as performance is concerned remember that headwinds are factored 50% and tailwinds 150% but calm is not factored at all.

Not being a technical person, I think I understand what you are saying, but just to make sure, could you expand on this a little for me?

Many thanks,

L337