Aaron747
Topic Author
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### 747-400 Climb Profile

In the above and several other 747-400 takeoff videos, (as well as personal experiences looking out the window) I have noticed that the high weight climb profile for the 744 seems to call for keeping flaps extended for the first few minutes of climb.

What, if any, would the exact parameters for this be in the FOM?

In the video, I would hazard a guess they departed at flaps 20 and maintained that setting for the first couple minutes of climb. Flaps 10 looked to be set another couple minutes with the wing not fully cleaned up until nearly 4 minutes after getting airborne. I am aware that the 744 and other similar-sized aircraft are not particularly great climbers at high weights by any measure, so I'm curious as to the benefits and trade-offs associated with leaving the flaps extended quite so long.

Many thanks in advance for satisfying my curiosity.
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Starlionblue
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### RE: 747-400 Climb Profile

 Quoting Aaron747 (Thread starter):In the above and several other 747-400 takeoff videos, (as well as personal experiences looking out the window) I have noticed that the high weight climb profile for the 744 seems to call for keeping flaps extended for the first few minutes of climb. What, if any, would the exact parameters for this be in the FOM?

Wild guess here but flaps cannot be retracted prior to a certain speed. So if you want to keep a certain angle of climb due to a required climb gradient at a high weight this predicates a lower speed on climbout. Ergo retraction later.

Anyway wild guess.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo

Francoflier
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Joined: Wed Oct 31, 2001 12:27 pm

### RE: 747-400 Climb Profile

 Quoting Starlionblue (Reply 1):Anyway wild guess.

Not wild at all.

Some departures call for speed limits until certain waypoints or altitudes. If that speed is below flap retraction speed (which varies with weight) then the flaps stay.
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vikkyvik
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Joined: Thu Jul 31, 2003 1:58 pm

### RE: 747-400 Climb Profile

I remember reading that at high TOW, a 747's min safe maneuvering speed (or whatever - I don't know the technical term) might be faster than the typical 250kt-under-10,000-feet speed limit at US airports. So my guess is, instead of requesting a higher speed, they leave the flaps out until they're clear of 10,000 feet (or clear of traffic that they may hamper by flying faster).
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Fabo
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### RE: 747-400 Climb Profile

Seems like a normal climb to me. Probably NADP1.

You climb until ~1500ft on takeoff speed, flaps out. Then you pull back to climb power and climb to 3000ft, still on take-off speed. Only then you start to speed up and retract flaps as you manage to speed up in a slight climb.

Could very well take a couple minutes for a heavy 747 to get to retraction... methinks.
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Francoflier
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### RE: 747-400 Climb Profile

 Quoting vikkyvik (Reply 3):might be faster than the typical 250kt-under-10,000-feet speed limit at US airports.

It is indeed faster than 250kt. Controllers are aware of that and grant high speed whenever requested, if possible.
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Aaron747
Topic Author
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### RE: 747-400 Climb Profile

 Quoting vikkyvik (Reply 3):might be faster than the typical 250kt-under-10,000-feet speed limit at US airports.

OK, so they're staying dirty to stay under the limit then. Would that suggest that even a 744 at heavy TOW is more slippery than she looks?

 Quoting francoflier (Reply 5):It is indeed faster than 250kt.

Assuming the usual step climb profile for a long 744 haul, would getting in the neighborhood of Va as quickly as possible be the ideal?
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B747FE
Posts: 217
Joined: Mon Jun 21, 2004 11:09 pm

### RE: 747-400 Climb Profile

 Quoting Aaron747 (Reply 6):OK, so they're staying dirty to stay under the limit then

If there is no other choice, yes. Normally is not necessary, as controllers clears us for high speed climb.

 Quoting Aaron747 (Reply 6):Would that suggest that even a 744 at heavy TOW is more slippery than she looks?

Not really. The -400 has full maneuver capability during the flap retraction, unless TOW is above 680,000 lbs. in which case we are bank angle limited until Vref + 100.

 Quoting Aaron747 (Reply 6):would getting in the neighborhood of Va as quickly as possible be the ideal?

Generally correct, until obstacle clearance or crossing altitudes restrictions are met. Then accelerate to climb speed.

Regards,
B747FE.
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Starlionblue
Posts: 18028
Joined: Fri Feb 27, 2004 9:54 pm

### RE: 747-400 Climb Profile

 Quoting B747FE (Reply 7):The -400 has full maneuver capability during the flap retraction, unless TOW is above 680,000 lbs. in which case we are bank angle limited until Vref + 100.

Out of curiosity, is that bank angle limit in place when flaps are out, or only during flap operation?
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo

B747FE
Posts: 217
Joined: Mon Jun 21, 2004 11:09 pm

### RE: 747-400 Climb Profile

 Quoting Starlionblue (Reply 8):Out of curiosity, is that bank angle limit in place when flaps are out, or only during flap operation?

Above 680,000 lbs. you are still limited to 15 degrees until reaching Vref + 100 regardless of flap position.
Flap retraction would normally be commanded from flaps 1 position to flaps up at Vref + 80 KIAS, which happens to be Va for a clean wing if the aeroplane is below 680,000 lbs.

Regards,
B747FE.
"Flying is more than a sport and more than a job; flying is pure passion and desire, which fill a lifetime"

Qantas744er
Posts: 1192
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### RE: 747-400 Climb Profile

 Quoting Aaron747 (Thread starter): Was killing time going through some videos on YouTube and got to wondering about this: http://www.youtube.com/watch?v=yAHLSKv2rOI In the above and several other 747-400 takeoff videos, (as well as personal experiences looking out the window) I have noticed that the high weight climb profile for the 744 seems to call for keeping flaps extended for the first few minutes of climb. What, if any, would the exact parameters for this be in the FOM? In the video, I would hazard a guess they departed at flaps 20 and maintained that setting for the first couple minutes of climb. Flaps 10 looked to be set another couple minutes with the wing not fully cleaned up until nearly 4 minutes after getting airborne. I am aware that the 744 and other similar-sized aircraft are not particularly great climbers at high weights by any measure, so I'm curious as to the benefits and trade-offs associated with leaving the flaps extended quite so long. Many thanks in advance for satisfying my curiosity.

United has been using NADP-1 off 28L and 28R for a few years now. Hence on the 744, (they do both flaps 10 and 20 departures) thrust reduction height to CLB thrust is 1500' AGL (United has no CLB-1 and CLB-2 derate on their 744) and acceleration height to VREF+100kt (clean speed) is 3000' AGL.

Off all other runways at SFO they use the standard NADP-2 profile, which on the 744 means acceleration at 800' AGL and thrust reduction to CLB at flaps 5.

 Quoting vikkyvik (Reply 3):I remember reading that at high TOW, a 747's min safe maneuvering speed (or whatever - I don't know the technical term) might be faster than the typical 250kt-under-10,000-feet speed limit at US airports. So my guess is, instead of requesting a higher speed, they leave the flaps out until they're clear of 10,000 feet (or clear of traffic that they may hamper by flying faster).

They will always accelerate to VREF+100kt (clean speed) on the 747 without asking ATC in the U.S. The reason being that ATC is well aware that a heavy 747 will have a clean speed above 250kt.

Some pilots prefer requesting, others simply go for it. After all, operating the aircraft safely trumps the 250kt/10000ft rule.

Also, having flaps 1 out until 10,000 would NOT make any pilot happy during icing conditions!

A very experienced B744 captain once said here, that in 20+ years of flying he had never encountered a situation where accelerating to VREF +100kt was not possible.
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Fabo
Posts: 1154
Joined: Tue Aug 16, 2005 1:30 am

### RE: 747-400 Climb Profile

 Quoting Qantas744ER (Reply 10):They will always accelerate to VREF+100kt (clean speed) on the 747 without asking ATC in the U.S. The reason being that ATC is well aware that a heavy 747 will have a clean speed above 250kt.

Not just that ATC are aware, it is actually stated in the FARs that the aircraft should maintain under 250 or minimum clean speed under 10K
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