744 Speed Control
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From: UK
744 Speed Control
I recent thread that has been discussing ATC speed control has got me thinking about the 747-400.
If we take LHR where speed control normally goes something like 250-220-180-160/4D, how do crews handle the the lengthy time required to extend from flaps 1-5? Correct me if I'm wrong, but with average weights, min clean speed is something in the region of 220-230 kts. When instructed to reduce to 180KIAS this would normally require flap extension from 1-through to 10. Do ATC just accept that it will take a 744 a while to reduce in this speed range, or do crews anticipate this by having flap 5 selected at the 220kt mark?
If we take LHR where speed control normally goes something like 250-220-180-160/4D, how do crews handle the the lengthy time required to extend from flaps 1-5? Correct me if I'm wrong, but with average weights, min clean speed is something in the region of 220-230 kts. When instructed to reduce to 180KIAS this would normally require flap extension from 1-through to 10. Do ATC just accept that it will take a 744 a while to reduce in this speed range, or do crews anticipate this by having flap 5 selected at the 220kt mark?
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By coincidence I flew exactly this profile this morning. Leaving the BIG hold I was at 254t so, as you have deduced, 180kts can only be flown at F10. We don't cheat at LHR anymore as ATC can see our mode selections 
Thus I called F1 approaching BIG for the "leave heading 265/ speed 220" and then F5 outbound to enable an actual 220kts to be selected and flown. Mrs director called for the usual turn-in over Crystal Palace "left heading 360/speed 180" which I anticipated by calling for F10 about 5 sec before her (psychic or what?). Therefore I was easily able to fly the speeds required and by selecting V/S of about 700 fpm a continuous descent profile as well.
All that was needed was a similar anticipation for F20 to be able to fly 160 to 4DME on the glideslope and throw the Dunlops out at 1500' for a stable approach gate at 1000'.
By getting all the flap selections called for in a timely fashion the slow extension time can be allowed for - all it takes is a little forethough.
Thus I called F1 approaching BIG for the "leave heading 265/ speed 220" and then F5 outbound to enable an actual 220kts to be selected and flown. Mrs director called for the usual turn-in over Crystal Palace "left heading 360/speed 180" which I anticipated by calling for F10 about 5 sec before her (psychic or what?). Therefore I was easily able to fly the speeds required and by selecting V/S of about 700 fpm a continuous descent profile as well.
All that was needed was a similar anticipation for F20 to be able to fly 160 to 4DME on the glideslope and throw the Dunlops out at 1500' for a stable approach gate at 1000'.
By getting all the flap selections called for in a timely fashion the slow extension time can be allowed for - all it takes is a little forethough.
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From: Seattle
For those new to the -400, "Drag management" may be a foreign concept. It's a slippery airplane, and does not "slow down and go down" well.
The answer in situations such as described above is to put out some flaps well before "needed" according to the Flap Speed bugs. As ETOPS shows, put out the flaps when you need them to start decelerating, or maybe earlier when the time required for Flaps 5 will be too long for comfort. In the -400 it is almost ALWAYS preferable to get the flaps out a bit earlier than "required," rather than try to salvage a high/hot/decelerating approach.
When you forget, speedbrakes CAN be used at Flaps 25 & 30. Just remember that they are not "recommended" because they WILL cause excessive deceleration and/or descent rates if held open too long...
The answer in situations such as described above is to put out some flaps well before "needed" according to the Flap Speed bugs. As ETOPS shows, put out the flaps when you need them to start decelerating, or maybe earlier when the time required for Flaps 5 will be too long for comfort. In the -400 it is almost ALWAYS preferable to get the flaps out a bit earlier than "required," rather than try to salvage a high/hot/decelerating approach.
When you forget, speedbrakes CAN be used at Flaps 25 & 30. Just remember that they are not "recommended" because they WILL cause excessive deceleration and/or descent rates if held open too long...
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Leaving aside particular aircraft foibles, I am pretty certain that there is NO ATC requirement to 'nail' the speed immediately. I assume (ATC??) that the speed requested is what they want for the vectors they will give you, which will depend on many things, and that they would EXPECT you to achieve it in a reasonable time, which I always take as closing the throttles and starting the reduction when requested.
- a note of caution for Intruder and others - use of speedbrake (in a 737) with flap above 5 will produce significant and possibly fatigue inducing tailplane buffet AND stall speeds are increased (10kts) with speedbrake, so my logic says that min flap speeds need to be thought about also. Whether this applies to the 747 I know not.
When you forget, speedbrakes CAN be used at Flaps 25 & 30. Just remember that they are not "recommended" because they WILL cause excessive deceleration and/or descent rates if held open too long...
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From: I wouldn't know.
Interesting for me as well as my company SOP allows selection of speedbrake up to flaps 10, but not at flaps 15 or greater. Thats classics only though and might be different for the NG (they had some speedbrake problems in the beginning on the NG iirc). In our AFMs is just a recommendation to not use speedbrake at 15 or greater, but it is still allowed according to the AFM.
Per Ardua ad Astraeus
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From: UK
Sorry - we are off on a 737 trail here
I 'grew up' on the 737 with Captains who threatened to remove my left arm if I used it at more than F5. I now do the same.
If you ever have the chance to sit at the back of a 737 when some ******** up front cannot control his speed without s/brake at Flap 5 or more try to watch the tailplane - I almost guarantee you will never do it yourself again. It is worth asking the rear c/c too if they notice the heavy vibration.
I 'grew up' on the 737 with Captains who threatened to remove my left arm if I used it at more than F5. I now do the same.
If you ever have the chance to sit at the back of a 737 when some ******** up front cannot control his speed without s/brake at Flap 5 or more try to watch the tailplane - I almost guarantee you will never do it yourself again. It is worth asking the rear c/c too if they notice the heavy vibration.
Warning Toxic!
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Worth watching the flaps too. Speedbrake with flap really shakes the flaps something horrible. I find it a little dismaying many pilots regard speedbrakes as a natural way to slow down everytime, rather than applying energy management. I've even caught some intentionally keeping higher altitude/speed in a circuit so that when it came time to descend/slow, they can whack out full speedbrake. It seems to escape them that speedbrakes are very good vibration devices and not very good slow-up devices!
The 747 doesn't take much longer than a 737NG in the deceleration phase. Flap to 5 takes longer, but the descent planning and slow-up phase is almost similar.
The 747 doesn't take much longer than a 737NG in the deceleration phase. Flap to 5 takes longer, but the descent planning and slow-up phase is almost similar.
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From: Seattle
- a note of caution for Intruder and others - use of speedbrake (in a 737) with flap above 5 will produce significant and possibly fatigue inducing tailplane buffet AND stall speeds are increased (10kts) with speedbrake, so my logic says that min flap speeds need to be thought about also. Whether this applies to the 747 I know not.
Speedbrake with flap really shakes the flaps something horrible. I find it a little dismaying many pilots regard speedbrakes as a natural way to slow down everytime, rather than applying energy management.
Also, those who use S/B for deceleration MAY have read a Boeing pub that implies that S/B and landing gear are the "only" drag-producing devices. A couple Check Airmen in our company chastise Pilots for using flaps above the bug speed for drag...
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S'funny, having flown the 737, 747-400 and A320 family, I know which one I consider least slippery, and as a clue it isn't the 737 or the Airbus.
The 747-400 may be more slippery than the classic, but once the flaps get to 5 it's anything but slippery - goes down like a brick and requires quite a bit of power to maintain the glideslope. It's the time that f5 takes to run that's the problem, the aircraft decelerates quicker than the flaps run (unless the deployment is started closer to lplacard speeds).
The A319 especially is a little b@stard to slow down (as, I believe, is a light 757) with relatively high residual thrust, and maintaining the glide rarely requires anything above idle thrust.
Maybe part of the perception is the relative lack of handling by us heavy metal drivers?
The 747-400 may be more slippery than the classic, but once the flaps get to 5 it's anything but slippery - goes down like a brick and requires quite a bit of power to maintain the glideslope. It's the time that f5 takes to run that's the problem, the aircraft decelerates quicker than the flaps run (unless the deployment is started closer to lplacard speeds).
The A319 especially is a little b@stard to slow down (as, I believe, is a light 757) with relatively high residual thrust, and maintaining the glide rarely requires anything above idle thrust.
Maybe part of the perception is the relative lack of handling by us heavy metal drivers?
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The 747-400 may be more slippery than the classic, but once the flaps get to 5 it's anything but slippery - goes down like a brick and requires quite a bit of power to maintain the glideslope.
Warning Toxic!
Disgusted of Tunbridge
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From: Hampshire, UK
I think a lot of what we perceive of as 'a slippery aeroplane' probably has more to do with high idle thrust settings on the engines rather than low drag fuselages, with the 747 big fans having possibly a higher inflight idle thrust setting due to the historic problems with big fans sometimes not responding to thrust lever demands. Certainly with the 747, once the flaps are mostly out, and all those wheels down, it becomes a flying brick!
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I am pretty certain that there is NO ATC requirement to 'nail' the speed immediately.
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From: Seattle
once the flaps are mostly out, and all those wheels down, it becomes a flying brick!
Both the 744 and the 742 become relative bricks with the rubber in the breeze. However, most pilots are more reluctant to drop the gear than to raise the speedbrakes! The other piece of that equation is that the gear is almost NEVER dropped if the pilot expects the drag requirement to be REDUCED after the lever is moved.
If the goal is to satisfy ATC AND the local populace, hanging the wheels out is NOT the answer! A bit of early flaps and a few extra N1s work a lot better...
BTW, put anti-ice and its higher N1 requirement into the equation, and the 744 is damn near impossible to "slam-dunk" without the wheels hanging!
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What about when it comes to holding in icing conditions? If i'm not mistaken, having the LE flaps extended prevents WAI. With the LTMA holding speed restriction of 220kts below FL140, the pattern would need to be flown with flaps 1 or 5. Hence no LE ice protection?
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From: Seattle
Holding while accumulating ice will soon develop into an emergency situation. Tell ATC you MUST hold at X speed min because of icing. If he doesn't like it, declare the emergency sooner rather than later.
I'd rather write the report than have my survivors read it...
I'd rather write the report than have my survivors read it...
