I imagine any pilot could answer this. At the bottom of the initial descent portion of a flight and when the wings are still clean and the power is at flight idle, how do you slow the aircraft down? Does an aircraft slow when it is leveled off? Raise the nose? I think someone told me that dumping the gear and lowered flaps slows a plane down but that this is not a sign of good airmanship. Are some airliners easier to slow than others at the bottom of the initial descent?

I think I read on another Forum, with regards to the Boeing 727, that if one could see the landing field over the nose of the aircraft, regardless of one's current altitude, that one could land on it. Not sure what was meant by that. I am guessing that this means that if one could see the runway, no matter how high one was in a 27 that one could descend and slow and land on it. If it is true, is that true of all airliners?

Aerodynamic drag due mostly to Cd and air density. About 10 knots per nm in the types I’ve flown. As the plane slows, to maintain level flight, AoA must increase which causes an increase in induced drag. Descent and slowing should be planned to avoid using drag devices for fuel savings.

Probably not newer designs, but the B727 could create awesome amounts of drag once below 270 with gear, speed brakes, then retract the boards start deploying the high lift devices. Gear down at 270 sounded terrible, but airspeed went away quickly.

Max spoilers on the Global with slats out could generate 5,000 to 6,000 fpm at lower altitudes, more than smart. Later, an AFM limitation was put on using the MAX position as it was for emergency descent and not tested for maneuvering. The C-5, fully configured, at 180 knots would descend at about 900-1,000 ft/mile but you had to slow it down first.

I would think you could use the speed brakes to slow down.

AirKevin wrote:

I would think you could use the speed brakes to slow down.

Yes, those, too. But good airmanship tries to avoid them.

Hold down the clutch and let it coast if manual. Drop down a gear and take your hand off the throttle if automatic.

Speed brakes (if I need to continue to get down) or just increasing the angle of attack to create induced drag to slow (I prefer this method).

TWA772LR wrote:

Hold down the clutch and let it coast if manual. Drop down a gear and take your hand off the throttle if automatic.

I find opening the window and holding the palm of my hand into the wind also helps.

WesternDC6B wrote:

TWA772LR wrote:

Hold down the clutch and let it coast if manual. Drop down a gear and take your hand off the throttle if automatic.

I find opening the window and holding the palm of my hand into the wind also helps.

But you have to slow to 200kts first to comply with the cockpit window speed limitation to open it.

Then i can use the flare gun as an impromptu heat seeking missile decoy launcher while inverted.

GalaxyFlyer wrote:

AirKevin wrote:

I would think you could use the speed brakes to slow down.

Yes, those, too. But good airmanship tries to avoid them.

Absolute nonsense. If needed, use them. This old cliche of ‘lever of shame and bad airmanship’ is nonsense. You can’t plan or foresee everything. I’d rather use speedbrakes than flaps to slow down. That’s also our company policy too as flaps are not meant to replace the speedbrakes. And with speedbrakes you are flexible in a way as you can vary your deceleration rate to fit what you need. You fo’t always need full speedbrakes. By extending flaps you are ‘locked’ in that config and deceleration rate.

convair880mfan wrote:

I imagine any pilot could answer this. At the bottom of the initial descent portion of a flight and when the wings are still clean and the power is at flight idle, how do you slow the aircraft down? Does an aircraft slow when it is leveled off? Raise the nose? I think someone told me that dumping the gear and lowered flaps slows a plane down but that this is not a sign of good airmanship. Are some airliners easier to slow than others at the bottom of the initial descent?

I think I read on another Forum, with regards to the Boeing 727, that if one could see the landing field over the nose of the aircraft, regardless of one's current altitude, that one could land on it. Not sure what was meant by that. I am guessing that this means that if one could see the runway, no matter how high one was in a 27 that one could descend and slow and land on it. If it is true, is that true of all airliners?

It's true, in the 727 if you could see it in the window, you could land on it. I proved it a time or ten You could drop it like a crowbar out of the sky. I went from that to the A320 series, the two couldn't be more different.

The Airbus doesn't really go down and slow down very well. I find the speed brakes to be mostly rumbling noise makers. I tend to keep the airspeed at 250 in an open, thrust idle descent. If that doesn't work 180 and Flaps 2 you have it made most of the time. For some reason a lot of guys, starting way back in initial training(me included), select 210 knots on an open, idle descent. The A320 doesn't do anything well at 210 knots, especially descend! It is pretty common coming into DTW to be abeam the field at 10-12,000' and 210 knots per the STAR constraints and be told to expect a short approach. I ask for speed relief to 250, usually well before being midfield if I sense it coming, otherwise I won't accept it because I won't be able to lose the altitude I need to lose.

In level flight, the rule of thumb is 10 knots deceleration per nautical mile at idle, or double that with speed brakes.

On the A330/A350, if you're descending and also need to slow down, it is often a good idea to just level off for a bit, decelerate, then resume descent. Much more relaxing than watching that speed tape glacially creep down but never fast enough...

Once you're below 200 knots, the speed brakes don't do very much in the 'bus as tb727 says. But by then you're at flaps one at least and have a fair bit of pitch angle on so it is less of a problem than trying to get from 280 to 210 before that speed constraint.

If you want to descend fast, on the other hand, you want to keep the speed up. At 300 knots we can easily get over 5000fpm descent with the speedbrakes.

You can always use the gear.

Avgeek21 wrote:

GalaxyFlyer wrote:

AirKevin wrote:

I would think you could use the speed brakes to slow down.

Yes, those, too. But good airmanship tries to avoid them.

Absolute nonsense. If needed, use them. This old cliche of ‘lever of shame and bad airmanship’ is nonsense. You can’t plan or foresee everything. I’d rather use speedbrakes than flaps to slow down. That’s also our company policy too as flaps are not meant to replace the speedbrakes. And with speedbrakes you are flexible in a way as you can vary your deceleration rate to fit what you need. You fo’t always need full speedbrakes. By extending flaps you are ‘locked’ in that config and deceleration rate.

Agreed - I have seen some speedbrake use on almost all my flights as a passenger. I mean obviously plan accordingly, but winds change, ATC vectors, etc etc, they are there for a reason!

Starlionblue wrote:

You can always use the gear.

OK perhaps my senses weren't playing tricks on me. I was a passenger on an A330 last week descending into ATL. They had speed brakes deployed seemingly all the way to pattern altitude, and were retracted just as I heard thrust being applied. A couple of minutes before then, I was 95% sure the gear came down. Granted this was at night, but looking out the window I thought "wow, that's an early deployment" based on our altitude. This was on right downwind to 26R.

Once on final, I doubted my earlier observation as the gear certainly came down (again?). That was a new one for me. Presumably with the speed brakes deployed for so long, they were getting down in a hurry.

This seems a little strange, given that we were flying into ATL - which I figured had pretty straight-forward STARs. After well over a hundred flights into ATL, that was certainly a first. Weather was great.

Why may this have been the case?

Most airports keep planes high on the downwind for sequencing with aircraft coming from the opposite cornerposts.

Then there will be a circumstance when there is no one on final and so the aircraft on downwind will be #1 for the runway.

You can tell when you’re the next one. Normally on downwind you’ll be stepped down from 11 to 8 to 6 to 3. But if there is no traffic you get cleared directly to 3000 from 11.

Options are to just accept it will take 20 miles to descend from 11000 to 3000 and then fly the 15 mile final to the runway, or hustle down by getting dirty and losing the altitude in 6 miles and only having a 5 mile final.

Sounds like your crew decided to get dirty.

I didn’t say don’t use the boards, just plan the descent to avoid them, if your plan doesn’t work out, go ahead. Boards are better than configuring way early, unless you need that, too.

Generally speaking, is it correct to say that flaps are for flying slower than cruise but not for actually slowing down?

Urban legend? ATC wanted a guy to descend faster and asked if he had speed brakes. Pilot reply “those are for my mistakes, not yours”.

IFlyVeryLittle wrote:

Generally speaking, is it correct to say that flaps are for flying slower than cruise but not for actually slowing down?

It really depends. Some aircraft have a much higher flap speed, at least for an initial setting, than they do gear speed. In that case, using flaps to slow down might actually be a good idea. These days, speed brakes are on most larger aircraft specifically to slow down and save configuring for later in the approach.

IFlyVeryLittle wrote:

Generally speaking, is it correct to say that flaps are for flying slower than cruise but not for actually slowing down?

As a general rule, yes. Flaps are for flying slower, not for slowing down.

Example. If we need to slow from 210 knots to 180 knots and the minimum clean speed is 203, you'd ask for flaps 1, then select 180 knots. The flaps will help you slow down, but they aren't extended to slow you down. They're extended because you need them below 203 knots.

An exception is if you really really need to land asap, e.g. uncontrollable fire. In this case you'd maintain as high a speed as possible until about 12-14 miles out, then extend speedbrakes. As soon as you slow below max gear speed, lower the gear, and as soon as you slow below each Vfe, extend flaps that step. Not so kind to the flaps, but it allows you to maintain high speed until the last possible moment by maximizing deceleration.

Welp, I remember a flight from Ft. Benning to Ft. Irwin on a C-141...All the pilot had to do was to open the deflector baffles on the doors for troops to jump out of.....airplane slowed down real quick...got kinda bumpy too!!.

bhill wrote:

Welp, I remember a flight from Ft. Benning to Ft. Irwin on a C-141...All the pilot had to do was to open the deflector baffles on the doors for troops to jump out of.....airplane slowed down real quick...got kinda bumpy too!!.

Probably not advisable to throw passengers out like that, though.

Do any aircraft prohibit simultaneous use of speed brakes and flaps? In my experience, the speed brakes usually get stowed before flaps are extended but I'm not sure if this is required or just a choice by the crews.

mxaxai wrote:

Do any aircraft prohibit simultaneous use of speed brakes and flaps? In my experience, the speed brakes usually get stowed before flaps are extended but I'm not sure if this is required or just a choice by the crews.

I believe between certain flap settings, you can't also use speed brakes.

mxaxai wrote:

Do any aircraft prohibit simultaneous use of speed brakes and flaps? In my experience, the speed brakes usually get stowed before flaps are extended but I'm not sure if this is required or just a choice by the crews.

B727 didn’t allow the combination of flaps and speed brakes, most newer types do with some restrictions. It’s rare you need both and probably more drag and quick energy loss than is advisable.

GalaxyFlyer wrote:

It’s rare you need both and probably more drag and quick energy loss than is advisable.

True, although there are some GA planes with linked speed brakes and flaps (so there's only one lever that moves both simultaneously). Makes steep descents really simple.

mxaxai wrote:

Do any aircraft prohibit simultaneous use of speed brakes and flaps? In my experience, the speed brakes usually get stowed before flaps are extended but I'm not sure if this is required or just a choice by the crews.

On the A330 and A350 there is no restriction. However if you're at speeds where you need Flaps 2 or more, speedbrakes aren't very effective anyway.

I use speedbrakes (usually multiple times) on just about every flight. Just part of the job.

On the Airbus A320 and A319, if speedbrakes are extended, they will auto retract if flaps are selected to FULL. On the A321, the speedbrakes retract if flaps are selected to 3 or greater.

On the A320 series, speedbrakes remain quite effective, even at slower airspeeds with flaps extended. The most common example of this, at my operator, is approach to KLAX Runways 24/25 where aircraft can be cleared for, and established on the ILS glideslope quite a distance from the airport (i.e., 25 - 30 DME from the airport). In most cases, we will be descending clean at 250 KIAS, normally at, or slightly above, idle thrust. When ATC requests us to reduce to 210 KIAS, 180 KIAS, and/or 165 KIAS, as required, speedbrakes are very effective in allowing the aircraft to slow to speeds at which flaps can be extended.

e38

GalaxyFlyer wrote:

mxaxai wrote:

Do any aircraft prohibit simultaneous use of speed brakes and flaps? In my experience, the speed brakes usually get stowed before flaps are extended but I'm not sure if this is required or just a choice by the crews.

B727 didn’t allow the combination of flaps and speed brakes, most newer types do with some restrictions. It’s rare you need both and probably more drag and quick energy loss than is advisable.

That may have been operator specific as we were able to use both if needed. Of course knowing the operator I flew the 727 for, well, enough said....It would drop like a rock though. We had a specific training maneuver with half spoilers and Flaps 15. At that point the spoiler/aileron PFM mixing box would give you movement of both the high-speed and low-speed ailerons and full spoiler up on one side and spoilers down on the other in a roll. The point of it was to show the accelerated roll rate in that configuration and to be careful if you were in that situation. It was very noticeable.


You couldn't use spoilers and flaps in the Learjet 20/30 series at the same time. The spoilers were either up or down and the wing is so tiny, the flow disruption from the spoilers with the flaps out as well would be worrisome.

That Falcon 20 we could use both but didn't really ever need to.

The A320 series we have talked about, not that they do much in my opinion with a clean wing, but you can use them to Flaps 3 fairly effectively. They won't come out in config Full.

mxaxai wrote:

Do any aircraft prohibit simultaneous use of speed brakes and flaps? In my experience, the speed brakes usually get stowed before flaps are extended but I'm not sure if this is required or just a choice by the crews.

On the 737NG/MAX we sometimes use Flaps and Speedbrakes combined. Always often on a last minute straight in approach clearance or establishing on the ILS and ATC want you to maintain a certain speed, or worse, slow down. Typically you’d be at Flaps 5, full speedbrakes for about 20-30 seconds than. I prefer to use Flaps 10 and see how it works but it gives very limited drag advantage over Flaps 5 so most often you’d have to resort to speedbrakes usage. Flaps 15 and speedbrakes gives a config warning and a mandatory air safety report in my company.

convair880mfan wrote:

I imagine any pilot could answer this. At the bottom of the initial descent portion of a flight and when the wings are still clean and the power is at flight idle, how do you slow the aircraft down? Does an aircraft slow when it is leveled off? Raise the nose? I think someone told me that dumping the gear and lowered flaps slows a plane down but that this is not a sign of good airmanship. Are some airliners easier to slow than others at the bottom of the initial descent?

I think I read on another Forum, with regards to the Boeing 727, that if one could see the landing field over the nose of the aircraft, regardless of one's current altitude, that one could land on it. Not sure what was meant by that. I am guessing that this means that if one could see the runway, no matter how high one was in a 27 that one could descend and slow and land on it. If it is true, is that true of all airliners?

Essentially the same as a car slows down when you take your foot off the gas. With a car it is mainly the friction of the wheels on the road.

With an aircraft it is mainly the friction with the air (simplicities), we call that drag.

The best way to slow an airliner down is to have both pilots on overtime.

I fly into LAW a lot on the E145. When high winds and/or inclement weather is moving thru, ATC keeps you high until you're about 25-30 miles from the field. Cruise is usually 16,000 feet, so it's a pretty quick descent. I'm pretty sure that the spoiler is just there so it could be certified. It definitely sounds like the aircraft is going to come apart at VLO, but helps you get down quick.

zeke wrote:

With a car it is mainly the friction of the wheels on the road.

Do you mean friction in the wheel bearings?

Also I think aerodynamic drag on a car is probably the main stopping factor if you're coasting.

vikkyvik wrote:

zeke wrote:

With a car it is mainly the friction of the wheels on the road.

Do you mean friction in the wheel bearings?

Also I think aerodynamic drag on a car is probably the main stopping factor if you're coasting.

Wheel friction likely comes from tire and road deformation. At low speed that would be the dominant energy loss, I assume.

kalvado wrote:

Wheel friction likely comes from tire and road deformation. At low speed that would be the dominant energy loss, I assume.

Perhaps true. Oddly, can't find many authoritative articles on the subject.

vikkyvik wrote:

Perhaps true. Oddly, can't find many authoritative articles on the subject.

It's called rolling resistance, and is a well understood concept. It is why trains are more efficient than busses or trucks at moving people and freight.


In response to the original question, in light aircraft pitch is your friend. Once the engine is at idle (a propeller is very effective at creating drag), your only real other tool is pitch. Slowing the rate of descent even by a small margin will have a large effect on the airspeed of the aircraft. This is especially the case as a lot of light aircraft have relatively low flap extension speeds, so you need to burn off energy to get below the flap speed.

Can you "slip" airliners? The C172 is bad at it, but for microlights it is great (left rudder, right aileron, and down you go).

TheSonntag wrote:

Can you "slip" airliners? The C172 is bad at it, but for microlights it is great (left rudder, right aileron, and down you go).

No slipping in airliners. The yaw damper takes care of the rudder, so you never touch the rudder pedals except for takeoff, landing, taxi and with an engine out.

That being said, it has been done. https://en.wikipedia.org/wiki/Gimli_Glider.

The last time someone tried to use the rudder aggressively (not to slow down though) AA587 happened.

https://en.wikipedia.org/wiki/American_ ... Flight_587