Landing flaps depending on aircraft weight
Thread Starter
Joined: May 2024
Posts: 1
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From: seoul
Landing flaps depending on aircraft weight
Hello,
Just had a quick question on landing flaps usage. I'm a trainee, about to fly B777.
which flap setting do you prefer to use in relation to aircrafts' landing weight? All this time, I thought it's favorable to use flaps 30 for light weight and flaps 25 for heavy weight.
However, a captain came up to me and said I had this all wrong. Could someone explain this in little more detail? (which flap setting to use depending on the landing weight and the reason why)
Thank you in advance
Just had a quick question on landing flaps usage. I'm a trainee, about to fly B777.
which flap setting do you prefer to use in relation to aircrafts' landing weight? All this time, I thought it's favorable to use flaps 30 for light weight and flaps 25 for heavy weight.
However, a captain came up to me and said I had this all wrong. Could someone explain this in little more detail? (which flap setting to use depending on the landing weight and the reason why)
Thank you in advance
Joined: Mar 2006
Posts: 2,633
Likes: 137
From: USA
I use 30 by default, unless something necessitates 25. I’ve never heard of weight influencing flap setting, unless you’re looking at a climb limit, but that’s more of a single engine factor. Flap 25 does give you SLIGHTLY better tail clearance though. If your landing technique is sound, this shouldn’t be an issue though. I’d rather go with 30 and have an approach speed 7-8kt slower.
Joined: Apr 2008
Posts: 83
Likes: 2
From: Central Europe
On the shorter 777 versions like -200 and 777F Vref30 is limited at light weights for controllability reasons (VMCL). Might be a sensible to use flaps 25 in normal ops on these tails if only light weight as the Vref30 and Vref25 will be very close or even the same and Flaps 30 with these speeds.
However I have no real world experience with this effect as we only operate the -300ER.
However I have no real world experience with this effect as we only operate the -300ER.
Joined: Nov 2007
Posts: 36
Likes: 2
From: RH base 36R
Many operators favor flaps 25 landings (even to the point of making it the standard landing flapsetting) because of fuel savings and noise reduction during the approach. However, as a crew you need to factor in all variables that may be relevant (such as runway length, head/tailwind, runway condition, landing weight, minimum runway occupancy time, resulting brake temperatures) and if you think flaps 30 would be the better/safer choice, then flaps 30 it is. As long as you are below max landing weight either flaps 25 or 30 is fine, based on your judgement of the mentioned factors. One is not more difficult than the other, just get familiar with the slight handling (flare) differences.
If you need to make an overweight landing, you may not be able to use flaps 30 because your approach speed is higher than the flaps 30 placard speed. The OVERWEIGHT LANDING procedure will give you guidance here, but it may be a good idea to have an idea of the weight above which you will need to use flaps 25 (or possibly flaps 20 if you have an engine out).
If you need to make an overweight landing, you may not be able to use flaps 30 because your approach speed is higher than the flaps 30 placard speed. The OVERWEIGHT LANDING procedure will give you guidance here, but it may be a good idea to have an idea of the weight above which you will need to use flaps 25 (or possibly flaps 20 if you have an engine out).
Joined: Dec 2002
Posts: 2,775
Likes: 353
From: UK
Safety involves minimising the risk of harm
Moody 
- -
Most regulators, either by recommendation or mandate, require a check of landing performance before making an approach to assess the safety of landing.
In the event of an overrun accident where the flap setting does not give the lowest landing distance, then this outcome could be considered as not minimising risk because a better performance option was available.
If so, then any approach with a flap setting with a lesser performance than available could be identified as involving more risk.
Relating safety to risk / risk management, then irrespective of outcome, any approach with a lesser flap setting would be less safe, (i.e. not minimising risk where a lower option existed).
Also, note the subtle difference between judging the risk in situational uncertainties vs the choice of known advantages of flap setting.
Also a difference as to when the risk is assessed; before the approach (preference / favour of flap setting) or from the overrun area (regret).
- -
Most regulators, either by recommendation or mandate, require a check of landing performance before making an approach to assess the safety of landing.
In the event of an overrun accident where the flap setting does not give the lowest landing distance, then this outcome could be considered as not minimising risk because a better performance option was available.
If so, then any approach with a flap setting with a lesser performance than available could be identified as involving more risk.
Relating safety to risk / risk management, then irrespective of outcome, any approach with a lesser flap setting would be less safe, (i.e. not minimising risk where a lower option existed).
Also, note the subtle difference between judging the risk in situational uncertainties vs the choice of known advantages of flap setting.
Also a difference as to when the risk is assessed; before the approach (preference / favour of flap setting) or from the overrun area (regret).
