B737 Flaps 25 on Approach
Joined: Mar 2009
Posts: 202
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From: Enroute to sand.
Our philosophy is F15-F30, and F15-F25-F40.
Theory:
Using F30 on route to F40 might lead to F30 landing,
where F25 will not lead to F25 landing (hopefully
).
The use of F25 as a transition flap makes things smoother, and easier to keep yourself away from max F40 speed in speed unstable weather conditions.
Theory:
Using F30 on route to F40 might lead to F30 landing,
where F25 will not lead to F25 landing (hopefully
). The use of F25 as a transition flap makes things smoother, and easier to keep yourself away from max F40 speed in speed unstable weather conditions.
Thread Starter
Joined: Oct 2006
Posts: 658
Likes: 1
From: Ankh Morpork, DW
Our philosophy is F15-F30, and F15-F25-F40.
Theory:
Using F30 on route to F40 might lead to F30 landing,
where F25 will not lead to F25 landing (hopefully
).
The use of F25 as a transition flap makes things smoother, and easier to keep yourself away from max F40 speed in speed unstable weather conditions.
Theory:
Using F30 on route to F40 might lead to F30 landing,
where F25 will not lead to F25 landing (hopefully
). The use of F25 as a transition flap makes things smoother, and easier to keep yourself away from max F40 speed in speed unstable weather conditions.
Per Ardua ad Astraeus
Joined: Mar 2000
Posts: 18,575
Likes: 4
From: UK
Interested in the answer. As I have said, it doesn't actually matter how you do it as long as both pilots are in the loop and recommended manoeuvre/limit speed are observed.
It took me 5 seconds the first time I had a call (from a 'newbie' just out of line training) for F30 from F15 to realise that something new was being taught, to check the call and decide it was safe and subsequently to clarify both with the P2 and a TC it was 'SOP'. If you want to use F2, brief it, and if you have no PFD, use F1 manoeuvre speeds (also briefed!).
Many years back a Captain, downwind at FNC, called for F40 from clean/210. It worked - but it should have been pre-briefed..
It took me 5 seconds the first time I had a call (from a 'newbie' just out of line training) for F30 from F15 to realise that something new was being taught, to check the call and decide it was safe and subsequently to clarify both with the P2 and a TC it was 'SOP'. If you want to use F2, brief it, and if you have no PFD, use F1 manoeuvre speeds (also briefed!).
Many years back a Captain, downwind at FNC, called for F40 from clean/210. It worked - but it should have been pre-briefed..
Joined: Nov 2007
Posts: 75
Likes: 0
From: england
Ecological disaster is, let's say you use 1 kg extra for leaving 40% N1 all the way thru flap extension:- (actually probably closer to 20kgs)
We have 1500 flights per day in my airline,, thats 1.5 tonnes x 364 (don't fly Xmas day), that's 564 tonnes! Get the point?
We have 1500 flights per day in my airline,, thats 1.5 tonnes x 364 (don't fly Xmas day), that's 564 tonnes! Get the point?
Joined: Mar 2001
Posts: 4,563
Likes: 35
From: I wouldn't know.
Yup, however only for the NG which displays them in the speedtape anyway. Classics do not seem to have them. However my last combined classic/NG FCOM is quite old (2008), we phased our last classics out in November 2008. But even our current NG FCOM has the flap speeds for Flaps 2 (Vref 40 + 40).
Joined: Feb 2011
Posts: 124
Likes: 0
From: Scandinavia
- it is indeed 'non-standard' in as much as you have absolutely NO idea what min manoeuvre speed is, do you?
When it comes to flap 25, it is recommended to avoid large trim changes during flap config. I believe this is the reason that all operators I've flown with use it in between 15 and 30.
Joined: Jun 2000
Posts: 4,507
Likes: 4
From: last time I looked I was still here.
When I flew B732 we flew fixed speed schedules. F0=210, F1=190, F2=180,
F5=170 F15-150. Now the speed tape shows a weight related man'vre speed of Vref40+40 for F2. F2 is 10kts slower than F1 and 10kts faster than F5. There are many places where 180kts is an ATC speed.
I like the reasoning that using F15-F30-F40 might cause a F30 landing by forgetfullness. This relates back to my point of not using F30 en-route F40 because there is no bug, but there is a F25 bug. Because there is a F25 bug this should alert you to the fact this is not therefore the landing flap setting.
F5=170 F15-150. Now the speed tape shows a weight related man'vre speed of Vref40+40 for F2. F2 is 10kts slower than F1 and 10kts faster than F5. There are many places where 180kts is an ATC speed.
I like the reasoning that using F15-F30-F40 might cause a F30 landing by forgetfullness. This relates back to my point of not using F30 en-route F40 because there is no bug, but there is a F25 bug. Because there is a F25 bug this should alert you to the fact this is not therefore the landing flap setting.
