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Speed control while descending.


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Hi,

When the flight is auto pilot mode,it perfectly speeds down to the mentioned speed.even when it is descending also it maintains the proper set speed.But when when I try to descent or even in the normal attitude the speed of the flight is increasing..during the approach it even touches 250 knots for a321. How effectively speed can brougjt in desired,what are the control and activities to do in the cockpit for reducing the speed..please please explain it with logic and principle. I mean flap10 means what? Spoilers means what impact etc...

THANKS

 

Sent from my GT-N7000 using Tapatalk

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Plan your descent, so you have enough almost level stretches in it where you can slow down the plane. Keep an eye on the throttles, especially when autothrottle is active. It may have a different idea about how the throttles should be set as you would need to slow down.

 

But even at throttles idle the plane will pick up speed if you descend fast enough (= repeat: plan ahead). In that case you can use the speedbrakes aka spoilers. These are metal sheets that are raised from the surface of the wings to increase drag and at the same time change the lifting properties of the wing (hence the name "spoilers" - they spoil the areodynamic of the plane). If your descent is planned right and the approach isn't too steep at this airport, you should not need them. But they are definitely raised when you touch down, to destroy the lift and slow the plane down. Flaps are metal sheets that extend outwards and down on the rear of the wings. They too change the profile of the wing and slow you down, but they increase lift, so you can fly slower without stalling. The larger the flap angle (5-10-15-25-35 degrees etc.) the more lift and drag is produced, and the slower the plane can fly. The last touch on approach is to lower the landing gear, this slows the plane down even further.

 

But be aware of the limitations.

- Speedbrakes you can apply at pratically any speed (within limits)

- Flaps can only be lowered to a certain degree below predefined speeds (that is what speedcards are for) or you will damage them and the plane may crash.

- Gear can only be lowered below a certain speed too, or you will damage it.

 

As for planning your descent: be aware that default FSX ATC does not manage this very well. They often will expect you to descend like a brick, which will increase your speed beyond limits. Better to call for descent ahead of TOD (request lower altitude) so you have more time to slow down.

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I never use the autopilot or autothrottle or auto-anything-else because it spoils the fun of flying manually.

To manually land I never do it by the boring book, instead I "ride" the big airliners down by the seat of my pants like a bush pilot, constantly juggling the throttle, spoilers and flap settings while pushing and pulling the joystick, it's great fun like I said.

Even Armstrong disengaged his autopilot and landed Apollo 11 manually..:)

 

PS- basically spoilers are like "gates" that pop up on top of the wings to spoil the smooth airflow over the wing and make the plane drop at a steeper angle without having to push the nose down.

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How effectively speed can brougjt in desired,what are the control and activities to do in the cockpit for reducing the speed

 

I can't tell you specifics as I don't fly those aircraft. But the primary method it is universal - reduce power and trim up. And secondarily, increase drag - gear, flaps, spoilers. It's just physics - the only thing that keeps your 80-ton lump of metal flying straight and level is the thrust from the engines. In a descent you have assistance from gravity.

 

With no engine power your minimum glide ratio will be about 15:1 (descend about 6000ft for every nautical mile). Trim it up to slow down, then add power to maintain the required descent rate. I would guess your aircraft's flight manual will have very specific procedures for all of this.

MarkH

 

C0TtlQd.jpg

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I agree with the other posters. When descending from a flight level however, I recommend using speed brakes. I find that using half of my available speed brakes works perfectly fine, depending on how fast I need to descend. If you are using payware airliners with a working FMC, it will usually tell you if you need speed brakes according to your VNAV descent profile with the message "drag required." Approach is a whole different ball game. If you are having trouble on your final approach, throw out everything you got. Speed brakes, gear, and flaps. Even in the simulator, it is appropriate to point out that pitch controls airspeed. Pitch up to bleed off airspeed, and plan your approach accordingly. Happy flying :o

"For once you have tasted flight you will walk the earth with your eyes turned skywards, for there you have been and there you will long to return." :pilot:

-Leonardo da Vinci

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I'd add that taking the flight lessons in FS (yes, in a lowly C-172) can help a lot in understanding how to fly -- the same principles apply and the Cessna is easier.

 

But I might add that if you're flying on autopilot and want to descend, just turn AP off (and autothrottle) then reduce power -- you'll descend.

 

Larry N.

As Skylab would say:

Remember: Aviation is NOT an exact Science!

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Thanks a ton all..I will trying all of your recommendations...sometimes what happens to me is speed comes down during the approach but flight will sink before hitting the runway. .

 

Sent from my GT-N7000 using Tapatalk

 

Shouldn't be unless you are not trimmed, or are actually dropping well below Vref before

you get to the runway.

Don't fly the Airbuses, but I assume they are slippery like the typical Boeing.

The 737NG is quite slippery. The 800 in particular.. They can descend, and they

can slow down, but they will often balk at doing both at the same time. This is where

planning ahead a bit can pay off. Even with a slippery plane, I rarely have to use

the speed brakes to slow down. Only in the worst case scenarios might I need to use em..

 

This video is pretty good as far as the typical approach in a 737.. I'm sure the Airbus

is a bit different, but not hugely so. They generally start slowing down from the usual

240 or so knots on the downwind. You generally want to be down to flaps up maneuvering

speed by the time you turn onto the base leg.

This video is of an autoland, but a manual approach and landing is the same as far as

the speeds and flaps sked.

 

https://www.youtube.com/watch?v=Bm02l989PUw&list=PLQR3X8_t24hh69ApDGWvrhIfYKMks2OKm

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Are you adding power to compensate for the extra drag of higher flaps settings? Gear coming out?

As mentioned, stay out ahead of the plane. Plan ahead. Give yourself enough time to descend at a reasonable rate (I have no idea what it's supposed to be in the AirBii). Make certain you are using hte correct power for the Flaps settings. You can fly around at say 10K ft MSL and do tests on that if you want. Same for gear. Add a setting of flaps, make sure you have the power set properly for that airspeed. Add another, check you power, etc etc. Bear in mind that engines don't respond instantly. They take time to "spool up" after the throttles are changed. If you add a final flaps setting very shortly prior to touchdown, perhaps the added drag is slowing you more than you think, and the engines aren't catching up in time. Make sure you are properly set up with trim, gear, flaps, setting engine RPM, sink rate, etc etc a couple miles out, then just settle on in. Cut the throttles (if that's the proper procedure on those) as you cross the threshold, about 10 or 20' AGL, not before.

The checklist is your friend!

Just trying to offer suggestions :)

Pat☺

[sIGPIC][/sIGPIC]

Had a thought...then there was the smell of something burning, and sparks, and then a big fire, and then the lights went out! I guess I better not do that again!

Sgt, USMC, 10 years proud service, Inactive reserve now :D

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