Boeing 737 flight spoilers
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Boeing 737 flight spoilers
On a recent pax flight on a 737 I noticed use of the flight spoilers when approaching to land.
Am I right in thinking that spoilers can be deployed at a higher airspeed than flaps?
Also, what benefit do the spoilers have vs flaps i.e. do they control descent rate or airspeed or both?
Thanks!
Am I right in thinking that spoilers can be deployed at a higher airspeed than flaps?
Also, what benefit do the spoilers have vs flaps i.e. do they control descent rate or airspeed or both?
Thanks!
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Spoilers reduce the created lift of the airfoil significantly. You can therefore use them to reduce speed, achieve a higher rate of descent or even both!
The 737 has no speed limit for the use of flightspoilers. The faster you are the more effective they are!
When using the flaps, placard speeds exist for each flap setting stating the highest IAS for deploying. The also help reducing speed (but creating extra lift) but Mr. Boeing recommends not to use flaps as speedbrakes since the stress on the flaps is undesirable!
Hope that answers your question!
Cheers
The 737 has no speed limit for the use of flightspoilers. The faster you are the more effective they are!
When using the flaps, placard speeds exist for each flap setting stating the highest IAS for deploying. The also help reducing speed (but creating extra lift) but Mr. Boeing recommends not to use flaps as speedbrakes since the stress on the flaps is undesirable!
Hope that answers your question!
Cheers
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Depends too if you were seeing them assymetrically deployed as roll augmentation when flaps down.
Was this an observation or a planned future comment to a fellow crewmember? Or both, haha?
Was this an observation or a planned future comment to a fellow crewmember? Or both, haha?
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When using the flaps, placard speeds exist for each flap setting stating the highest IAS for deploying. The also help reducing speed (but creating extra lift) but Mr. Boeing recommends not to use flaps as speedbrakes since the stress on the flaps is undesirable
While they may stay within flap airframe limit speeds (usually much higher than minimum manoeuvre speeds for the flap settings conccerned), there is evidence that pilots often cannot be bothered with excellence in flying, so they say it doesn't matter a stuff and go ahead and call for Flaps one through to Flaps Five while still descending and at speeds above the recommended.
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The FCOM [NGs] say do not extend spoilers below 1000 AGL. The "SPEEDBRAKE EXTENDED" Amber light will illuminated below 800 AGL. Our company has an additional restriction which says do not use speedbrakes with Flaps more than 15.
D O G
As per our procedures, while doing a CDA or a decelerated approach, we use F5 till 2000 AGL and then select the gear. This gives a "near" idle thrust descent and normally spped stays within limits. If speed starts to increase, we simply select gear early.
hope it helps
cheers
D O G
As per our procedures, while doing a CDA or a decelerated approach, we use F5 till 2000 AGL and then select the gear. This gives a "near" idle thrust descent and normally spped stays within limits. If speed starts to increase, we simply select gear early.
hope it helps
cheers
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Southwest has own limitation of no flaps at all with speedbrake usage. The party line is "Boeing engineers told us so" even though it's not in Boeing's manual. Any other self imposed restrictions out there besides the flaps 15 just mentioned?
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Our company has an additional restriction which says do not use speedbrakes with Flaps more than 15
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Hi
"The 737 has no speed limit for the use of flightspoilers. The faster you are the more effective they are"
"The 737 has no speed limit for the use of flightspoilers. The faster you are the more effective they are"
I found this reading an "Emergency descent" article for the 737NG
"Remember that use of speedbrakes at speeds in excess of 320 kts could result in a severe vibration which, in turn, could cause extreme damage to the horizontal stabilizer"
However 320 IAS is close to the VMO which is 340 IAS.
"Remember that use of speedbrakes at speeds in excess of 320 kts could result in a severe vibration which, in turn, could cause extreme damage to the horizontal stabilizer"
However 320 IAS is close to the VMO which is 340 IAS.
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The 737 has no speed limit for the use of flightspoilers. The faster you are the more effective they are!
I found this reading an "Emergency descent" article for the 737NG
"Remember that use of speedbrakes at speeds in excess of 320 kts could result in a severe vibration which, in turn, could cause extreme damage to the horizontal stabilizer"
However 320 IAS is close to the VMO which is 340 IAS.
"Remember that use of speedbrakes at speeds in excess of 320 kts could result in a severe vibration which, in turn, could cause extreme damage to the horizontal stabilizer"
However 320 IAS is close to the VMO which is 340 IAS.
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A3757 states: I would hazard a guess and say most 737 operators pay lip service to the FCTM advice of "Normal descents are made in the clean configuration to pattern or instrument approach altitude...if greater descent rates are desired, extend the speed brakes."
While they may stay within flap airframe limit speeds (usually much higher than minimum manoeuvre speeds for the flap settings conccerned), there is evidence that pilots often cannot be bothered with excellence in flying, so they say it doesn't matter a stuff and go ahead and call for Flaps one through to Flaps Five while still descending and at speeds above the recommended.
Would you care to elaborate? I know of no airline that does such as you suggest here is common practice. If you could quote your source for such a contentious and defamatory statement, I would be most grateful. If you are merely speculating, as seems the case, then please delete your rubbish post.
While they may stay within flap airframe limit speeds (usually much higher than minimum manoeuvre speeds for the flap settings conccerned), there is evidence that pilots often cannot be bothered with excellence in flying, so they say it doesn't matter a stuff and go ahead and call for Flaps one through to Flaps Five while still descending and at speeds above the recommended.
Would you care to elaborate? I know of no airline that does such as you suggest here is common practice. If you could quote your source for such a contentious and defamatory statement, I would be most grateful. If you are merely speculating, as seems the case, then please delete your rubbish post.
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use of speedbrakes at speeds in excess of 320 kts could result in a severe vibration which, in turn, could cause extreme damage to the horizontal stabilizer
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Controller: ABC1234 increase rate of decent
Pilot: unable
Controller: Don't you have speedbrakes?
Pilot: Yes, we do. But they are for my mistakes, not for yours...
Pilot: unable
Controller: Don't you have speedbrakes?
Pilot: Yes, we do. But they are for my mistakes, not for yours...
Last edited by TheWanderer; 13th Aug 2009 at 06:58. Reason: edited for layout
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Try to avoid speedbrakes like the devil will avoid the holy water.
The 5 P rules: Proper Planning Prevents Poor Performance!
IMHO if speedbrakes are needed, then something has gone wrong in the previous part of the descent.
Speedbrakes produce drag and are uncomfortble to passengers. If you need speedbrakes, you burned to much fuel in cruise or level flight earlier -> start your descent earlier.
There are other options that are more comfortable to passengers than speedbrakes.
The 5 P rules: Proper Planning Prevents Poor Performance!
IMHO if speedbrakes are needed, then something has gone wrong in the previous part of the descent.
Speedbrakes produce drag and are uncomfortble to passengers. If you need speedbrakes, you burned to much fuel in cruise or level flight earlier -> start your descent earlier.
There are other options that are more comfortable to passengers than speedbrakes.