Flaps 30 or Flaps 25 for landing in a gust?
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Join Date: Apr 2008
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Flaps 30 or Flaps 25 for landing in a gust?
Hi there,
What is your take? Care to comment?
Flaps 30 lower stall speed but a larger portion of flaps are exposed to gust load. What is ur take?
What is your take? Care to comment?
Flaps 30 lower stall speed but a larger portion of flaps are exposed to gust load. What is ur take?
Join Date: Apr 2010
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Not sure about what your type is, but generally you want lower flaps in gusty conditions, as you generally have more margin to Vfe (Vref increases less than the Vfe) and better performance in case of go-around/windshear escape manuever.
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I have answered this before for Airbus 320.
For better handling it's Flap full in turbulence or gust and Flap3 if expecting windshear for better performance. The aircraft is more sensitive in flap3.
For better handling it's Flap full in turbulence or gust and Flap3 if expecting windshear for better performance. The aircraft is more sensitive in flap3.
Last edited by vilas; 24th Jul 2021 at 10:38.
Gust load as in a VG diagram is a vertical gust and not a horizontally veering wind gust in a surface wind.
You’re not increasing the G-loading on the airplane with a gusting crosswind.
In a light GA airplane I would go with the lesser flap setting as go around climb performance tends to be very anemic with full flap.
In large aircraft you would increase Vref with half the headwind component and the full gust.
Obviously with a maximum.
In that case you would usually go with the lower flap setting as you would get close to the max flap speed.
Both cases flap 25.
You’re not increasing the G-loading on the airplane with a gusting crosswind.
In a light GA airplane I would go with the lesser flap setting as go around climb performance tends to be very anemic with full flap.
In large aircraft you would increase Vref with half the headwind component and the full gust.
Obviously with a maximum.
In that case you would usually go with the lower flap setting as you would get close to the max flap speed.
Both cases flap 25.
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Flaps 30 & 25 are normal flap settings for both the B777 & B787, Flaps 25 gives a 3 knots increase in Vref compared to Flaps 30 but an increase in marging to Vfe as mentioned by other posters, combine this with better handling and windshear go around characteristics a lower flap setting is always recommended when flying in gusty conditions if performance allows.
I found F25 in the 757 made life significantly easier in gusty conditions, you didn’t need that additional lift and drag of F30, you almost had to shoot it down anyway as it was more like a big kite
With F25 it went where you put it, furthermore the nosewheel could be lowered nice and gently,,whereas with F30 it could really crash down if you didn’t pay attention as a few crews have discovered and a few airframes badly damaged or even written off
The lower flap setting changed the target speed by 3 knots and made the 757 handle so much better I started using it for every landing
With F25 it went where you put it, furthermore the nosewheel could be lowered nice and gently,,whereas with F30 it could really crash down if you didn’t pay attention as a few crews have discovered and a few airframes badly damaged or even written off
The lower flap setting changed the target speed by 3 knots and made the 757 handle so much better I started using it for every landing
