744 PFD Flaps markers

[Captain Caveman 1]

Hi on the PFD on the speed bar there are what i asume to be flaps markers.they read UP, 5 , 10 ect....and are on selected speeds. but to me they seem very low. i usualy deploy the flaps much sooner.is it me thats is doing it wrong?

[crvm 0]

What makes you assume that what you see "seems" to low? Did you mean to say "too fast"? You retract the flaps as your approach each flap speed setting period. Best,Randy J. Smith

[Captain Caveman 1]

i mean on approach, or doesnt it count there?i mean that the aircraft has so low speed when comming to the flaps that if the airplane isnt decending the nose go very much up in order to maintain its altitude.so to me it seems that the flaps should come at a higher speed to maintain proper lift.

[markadeane 272]

They represent the minimum recommended speed for that flap setting, this gives you a margin of safety above the minimum manoevuring speed, below which you're in trouble. There's nothing to stop you from setting the next notch of flaps at a slightly higher speed, as long as you have the relevant flap setting selected AT OR ABOVE the speed shown, you'll be fine. Don't let the aircraft go below the indicated flap speed or you'll get a beautifully modelled demonstration of just how much intertia and energy (or lack thereof) is at play in a slow flying 747!!!It's not recommended to lower the flaps too far above the recommended speed as this adds drag to the airframe earlier than required, thus affecting your operating costs.But hey, in a virtual world, who cares about operating costs?!

[Guest aarskringspier]

>They represent the minimum recommended speed for that flap>setting, this gives you a margin of safety above the minimum>manoevuring speed, below which you're in trouble. >>There's nothing to stop you from setting the next notch of>flaps at a slightly higher speed, as long as you have the>relevant flap setting selected AT OR ABOVE the speed shown,>you'll be fine. >>Don't let the aircraft go below the indicated flap speed or>you'll get a beautifully modelled demonstration of just how>much intertia and energy (or lack thereof) is at play in a>slow flying 747!!!>>It's not recommended to lower the flaps too far above the>recommended speed as this adds drag to the airframe earlier>than required, thus affecting your operating costs.>>But hey, in a virtual world, who cares about operating>costs?!I guess we dont care about ripping the flaps off the wings either?

[markadeane 272]

> I guess we dont care about ripping the flaps off the wings either?:DWell, ok. If we're dropping flaps THAT far above the appropriate speed then it's a wonder we GOT off the ground to start with, let alone to the approach phase!Good point though, I'll quantify my earlier statement: a 'slightly higher speed' can be anything within - say - 20 knots of the minimum recommended speed down to flaps 20. Beyond flaps 20, you won't want to be more than 10 knots or so over the minimum recommended speed when lowering the next notch.Back to one of the original poster's points, if you're finding youself too slow (and nose high) in the approach, consider the timing of your deceleration.Speed-wise, I find the following works *for me*, though obviously weight comes into play so will vary a bit. As you go, set flaps according to the speed tape and lower the gear when you get to flaps 20.-240 below 10,000 feet-220 knots downwind (or below 6,000 feet if you're going straight in)-200 knots abeam the end of the runway (or within 8 miles of joining the approach)-180 knots as you turn base (or as you get within 5 miles of joining the approach)-160-180 knots as you prepare to intercept the approach (weight dependent, but basically I'm aiming to be at Vref +30 knots at this point)-Once established on final descending through 2,000 feet, reduce speed to Vref (+5 if you like) and lower landing flaps.

[craig_read 43]

Yes! Who cares about running costs.. flaps 30 and full thrust for me all the way!.. hehe.. just kidding..From watching various videos... the flaps don't get fully extended till quite late on in the approach.. I often deploy mine to full extension just before or after I hit the 160knot approach speed restriction... If you watch some of the videos of wing views on the 744 on approaches you'll see they're still extending at quite low altitudes..Craig

[crvm 0]

Well since we are talking approach - there is a way pilots deploy that takes into account the time for each flap to extend and the time at which they move the lever so as to make each flap transition smoother for the PAX. So yeah it is different coming down than going up (which is what I thought he meant) as Mark stated, the min spd is now on the underside instead of the top side ;-).Best,Randy J. Smith

[Guest 777jockey]

>Don't let the aircraft go below the indicated flap speed or>you'll get a beautifully modelled demonstration of just how>much intertia and energy (or lack thereof) is at play in a>slow flying 747!!!HAHAHA! Extremely well-said advice!

[Guest aarskringspier]

>> Well since we are talking approach - there is a way pilots>deploy that takes into account the time for each flap to>extend and the time at which they move the lever so as to make>each flap transition smoother for the PAX.>> So yeah it is different coming down than going up (which is>what I thought he meant) as Mark stated, the min spd is now on>the underside instead of the top side ;-).>>>>Best,>Randy J. SmithTHats the way I try to do it my goal is to time the flap extension to where it is fully extended for the setting on the PFD when the speed reaches that point.

[cowpatz 243]

If ever you have had the opportunity to look at the real flap system onn a 747 then you will begin to have a new appreciation for flap operation. As we know the leading edge devices are pneumatically powered by a series of air motors positioned along the leading edge. Each of these rotates a series of driveshafts that connects to bellcranks and then a connecting roads to the flap surfaces. It is one #### of a mechanical setup! The trailing edge flaps are powered by hydraulics via large screw jacks. The flaps are also very complex being triple slotted (meaning we have 3 flap segments) all held together with various linkages and covered over by canoe fairings that are soooooo big if you took one off and turned it upside down a family could go fishing in it!So what is my point?Give consideration to this mechanical marvel out there on the wing. It suffers from wear and tear and needs considerable maintenance. The higher the speeds you deploy the flaps the more the strain and the more wear and tear. Speedbrake should be used to slow up in preference to flap usage. Flap retraction and deployment should be done at or as close as feasible to the indications on the speed tape. Under normal conditions and if autothrottle is enaged, then you do not need to wait for the flaps to be in position before bugging the speed back to the next setting. Of course if you find yourself in a situation that warrants the use of flap earlier then do it, up to the placarded maximum speeds. If you find that you are doing this regularly then think about modifying your operating technique. As a general guide if your landing weight is below 250 tonne then you should be able to fly down the GS with flap 5 initially. A headwind component will have a big effect on your ability to reduce speed in this configuration so if it is calm then make sure you are close to desired speed before heading off down the slope. Speed brake is not that effective at these low speeds. At heavier weights use F10. This gives a nice comfortable and stable speed down the slope. At 1500 ft AGL select gear down and F20. At a 1000 ft select landing flap. If you are going to autoland and/or the weather is not great then think about either a full drag approach or set yourself up a bit earlier. This will make vertical spped monitoring easier and trim adjustments less frequent which will make the whole operation a lot more stable. Flap 25 will minimise flap wear but increase the nose attitude slightly and add about 5 to 7 kts to the landing speed and add about 200 m to the landing roll.If ever you get the opprtunity to fly in a 747 and get a window seat just to the rear of the wing have a look at the TE flaps when they are fully deployed. They shake around like crazy.Happy flying and look after those flaps!CheersSteve

[markadeane 272]

> If ever you get the opprtunity to fly in a 747 and get a window seat just to the rear of the wing have a look at the TE flaps when they are fully deployed. They shake around like crazy.

[Guest Totalbeginner]

I find the following works pretty well for approach...Fly 250KIAS clean.As you pass 240KIAS select FLAPS 1At 220kts select FLAPS 5Aim to have flaps 10 when on intercept heading and select when leaving 200kts to be extended by 180ktsWhen glideslope is 1.5dots up select GEAR DOWN and FLAPS 20Set speed bug to 160KIASAs you reduce to VAPP+5 extend to FLAP 25/30If a lower speed is required on the intercept leg, i.e 170KIAS then you may need flap 20 depending on the weight. Regards, Martin Neep

[markadeane 272]

That experience came from my third or fourth flight in the PMDG 744. I was accustomed to flying the 767-300 and was making an ILS approach into Sydney after a 3 hour flight from Auckland, heavily loaded. I was a bit tired and the weather was bad, I just went into '767 mode' during the approach and bought the speed back WAY too far, as I intercepted the localiser I looked outside the window and saw that my nose was well up and was in a left turn with about 15-20 degrees bank. Things were NOT looking good. I was basically right on the stick shaker speed when I started the go around. Even with the thrust right up at the GA limit, the aircraft took an eternity to start accelerating and all the while was sinking VERY fast towards the waters of Botany bay! I got it sorted but only just!

[cowpatz 243]

Of course what ever works for you is fine. Just bear in mind that flap speeds are based on VREF which varies with weight. Why bother having speeds to remember when it is all there on the speed tape for you?CheersSteve