Wind GUSTS
Thread Starter
Joined: May 2003
Posts: 831
Likes: 0
From: The Roman Empire
Wind GUSTS
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
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
Joined: Feb 2004
Aviation Qualifications: ATPL
Posts: 3,689
Likes: 118
From: USA
wind gusts
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.
Joined: Jun 2001
Posts: 3,991
Likes: 8
From: UK
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
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
Joined: Mar 2003
Posts: 63
Likes: 0
From: .
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
In short the “Boeing version” is representative for these documents.
ATIS/METAR gusts are also defined by official documents, eg. ICAO
Joined: Sep 2003
Posts: 97
Likes: 0
From: Amidst the dust and the flies, somewhere in Western Australia
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
Not foolproof by any means, but better than suck it and see.
Regards
the lunatic fringe
Joined: May 2001
Posts: 621
Likes: 5
From: Everywhere
As far as performance is concerned remember that headwinds are factored 50% and tailwinds 150% but calm is not factored at all.
Many thanks,
L337
