Gust additives
Joined: Feb 2018
Posts: 800
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From: East of Westralia
Joined: Feb 2018
Posts: 800
Likes: 279
From: East of Westralia
Joined: Jul 2004
Aviation Qualifications: ATPL
Posts: 278
Likes: 10
From: Europe
Shooting themselves in the foot on the 737-800 whose wing has a tendency to fly forever. Not me but I've witnessed it time and time again. It gets even more interesting when for mum and dad additives are also kept till touchdown. I'm a firm believer that correct speed and touchdown point are of great importance for a successful landing
Joined: Mar 2006
Posts: 2,633
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From: USA
On the various types from different manufacturers I've flown, unless it's extremely windy or there are very strong gusts, I'll carry all the speed down to about 50ft, where I'll allow it to bleed off to the usual Vls or Vref at touchdown. Not always successful, but there's no point in carrying the extra 15kt all the way to the flare then having to fight a wing that's not quite ready to land.
Fleet Manager
Joined: Apr 2001
Aviation Qualifications: ATPL
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From: various places .....
Joined: Apr 2015
Posts: 44
Likes: 13
From: Glasgow, EGPF
But every aircraft I’ve flown, the performance figures are based on being at Vref at 50ft and some unspecified lower speed at touchdown, so effectively you are keeping the additive with that technique.
All types are also equally vague about when/if you are meant to bleed the speed off. But since the way we plan flights you should be able to land with zero headwind then additional airspeed is not an issue from a performance perspective - the logical basis of gs mini on the Airbii. So it comes down primarily to the handling of each type whether it needs the speed bled off or not.
All types are also equally vague about when/if you are meant to bleed the speed off. But since the way we plan flights you should be able to land with zero headwind then additional airspeed is not an issue from a performance perspective - the logical basis of gs mini on the Airbii. So it comes down primarily to the handling of each type whether it needs the speed bled off or not.
Joined: Jan 2006
Aviation Qualifications: CPL
Posts: 1,410
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From: Between a rock and a hard place
It's all a bit academic when the airspeed indicator is all over the place, me thinks...
Make sure you land it in the correct spot, not on the nose wheel. Most important.
Make sure you land it in the correct spot, not on the nose wheel. Most important.
Joined: Apr 2022
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From: Italy
Joined: Jul 2004
Aviation Qualifications: ATPL
Posts: 278
Likes: 10
From: Europe
The 737NG allows down to Vref-5kt at touchdown, come in faster than strictly needed and likely say bye to the correct touchdown point. If it's extremely gusty then of course it's going to be a wrestling match. Nothing wrong cutting the power abruptly at 10ft if at that point you find yourself with excess speed, from that height you will definetely manage on that aircraft.
Joined: Mar 2006
Posts: 1,115
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From: England
The certification requirements specify a landing demonstration from Vref - 5 at the threshold, without power intervention; thus touchdown speed could be lower.
Performance data calculated by the OLD/FOLD method is based on the planned speed at the threshold, and a speed loss of 7kts during the flare.
The baseline is Vref, thus any approach speed additive - any planned for adjustment at the threshold, must be considered, which will increasing the landing distance required.
As yet no guidance has been found for adjusting distance for speed additives retained during the flare.
A sensible interpretation would be to use the planned threshold speed plus a further 7 kts as the basis for landing, which could result in a very large distance increment:
AC 91-79B 5.2.2 Excess Airspeed; (at the threshold)," As a rule of thumb, on dry or wet runways, a 10 percent increase in final approach speed results in a 20 percent increase in landing distance. "
If the additional speed durning the flare was considered in a similar manner as a tailwind, then "The effect of a tailwind increases the landing distance by 21 percent for the first 10 kts of tailwind."
https://www.faa.gov/documentLibrary/...91-79B_FAA.pdf
Performance data calculated by the OLD/FOLD method is based on the planned speed at the threshold, and a speed loss of 7kts during the flare.
The baseline is Vref, thus any approach speed additive - any planned for adjustment at the threshold, must be considered, which will increasing the landing distance required.
As yet no guidance has been found for adjusting distance for speed additives retained during the flare.
A sensible interpretation would be to use the planned threshold speed plus a further 7 kts as the basis for landing, which could result in a very large distance increment:
AC 91-79B 5.2.2 Excess Airspeed; (at the threshold)," As a rule of thumb, on dry or wet runways, a 10 percent increase in final approach speed results in a 20 percent increase in landing distance. "
If the additional speed durning the flare was considered in a similar manner as a tailwind, then "The effect of a tailwind increases the landing distance by 21 percent for the first 10 kts of tailwind."
https://www.faa.gov/documentLibrary/...91-79B_FAA.pdf
Joined: Feb 2008
Posts: 72
Likes: 41
From: AUS
Shooting themselves in the foot on the 737-800 whose wing has a tendency to fly forever. Not me but I've witnessed it time and time again. It gets even more interesting when for mum and dad additives are also kept till touchdown. I'm a firm believer that correct speed and touchdown point are of great importance for a successful landing
Joined: Mar 2006
Posts: 2,633
Likes: 137
From: USA
On the various types from different manufacturers I've flown, unless it's extremely windy or there are very strong gusts, I'll carry all the speed down to about 50ft, where I'll allow it to bleed off to the usual Vls or Vref at touchdown. Not always successful, but there's no point in carrying the extra 15kt all the way to the flare then having to fight a wing that's not quite ready to land.
Thread Starter
Joined: Apr 2001
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From: surfing, watching for sharks
On the various types from different manufacturers I've flown, unless it's extremely windy or there are very strong gusts, I'll carry all the speed down to about 50ft, where I'll allow it to bleed off to the usual Vls or Vref at touchdown. Not always successful, but there's no point in carrying the extra 15kt all the way to the flare then having to fight a wing that's not quite ready to land.
