Usage of speed brakes, v/s, etc.
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Usage of speed brakes, v/s, etc.
I know I've made quiet a few threads lately, but im sure a lot of other newbies also gain from the advice of the more experienced on this forum.
I apologize nevertheless for asking too much, but again have some questions.
I was barely taught to use speed brakes, and v/s etc on TR, and now on line I see a lot of captains playing around with v/s which is very new to me.
I understand that you shouldn't or wouldn rather not use v/s to increase rate of descent that often, because it could increase speed a lot, but you would rather use speed brakes, correct?
If finding yourself below profile, use it to reduce rate of descent, and it will continue to maintain speed with no problems?
Can you use speed brakes and v/s both together?
ATC asked you to descent at 2500 ft per minute and maintain 250 knots.
What happens if you speed select 250 and put v/s 2500?
I assume the v/s is the priority and speed is disregarded? In this case do you use speed brakes to slow down?
Please feel free to add other examples, and any tricky stuff that you find ATC asking you to do, anything is useful.
Thanks in advance guys !
I apologize nevertheless for asking too much, but again have some questions.
I was barely taught to use speed brakes, and v/s etc on TR, and now on line I see a lot of captains playing around with v/s which is very new to me.
I understand that you shouldn't or wouldn rather not use v/s to increase rate of descent that often, because it could increase speed a lot, but you would rather use speed brakes, correct?
If finding yourself below profile, use it to reduce rate of descent, and it will continue to maintain speed with no problems?
Can you use speed brakes and v/s both together?
ATC asked you to descent at 2500 ft per minute and maintain 250 knots.
What happens if you speed select 250 and put v/s 2500?
I assume the v/s is the priority and speed is disregarded? In this case do you use speed brakes to slow down?
Please feel free to add other examples, and any tricky stuff that you find ATC asking you to do, anything is useful.
Thanks in advance guys !
It depends on aircraft type. In an old airbus the speed is controlled by the autothrust and the V/S is the pitch mode. I generaly would select the speed about 5 knots less as this keep auto thrust changes to a minimum,but you must be prepared to accept some speed variation around your target.
You can use speedbrakes and V/S but you need to be aware that this can lead to the autothrust in some circumstances increasing thrust and fighting against the drag of the speedbrakes. This is obviously not very fuel efficient.If you wish to increase your rate of descent I would utilize a mode which gives idle thrust(LVL Change or OpDes),and extend the brakes. If this is still not enough then I would either increase speed or alternatively extend the gear depending again on circumstances.
You can use speedbrakes and V/S but you need to be aware that this can lead to the autothrust in some circumstances increasing thrust and fighting against the drag of the speedbrakes. This is obviously not very fuel efficient.If you wish to increase your rate of descent I would utilize a mode which gives idle thrust(LVL Change or OpDes),and extend the brakes. If this is still not enough then I would either increase speed or alternatively extend the gear depending again on circumstances.
Last edited by tubby linton; 8th Jun 2012 at 16:14.
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250kts & 2500fpm descent?
Sorry, sometimes you just have to say "unable". You might offer one or the other but both at the same time (depending on variables) may be impossible.
Sorry, sometimes you just have to say "unable". You might offer one or the other but both at the same time (depending on variables) may be impossible.
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ATC is there for you and not the other way around. IF they want me to slow down and descent at a high V/S then I'll tell them that they've got a choice, either speed or v/s/altitude. Sometimes it's daft using speedbrakes for what ATC is trying to achieve and it's just wasting too much 'free' energy.
On the Embraer V/S is not used. We use Flight Path Angle instead. But yes, you can use speedbrakes in both modes.
In v/s you are not speed protected so we tend to use Flight Level Change or FPA. In FPA you are also not speed protected. but it maintains a given descent angle irrespective of config/speed/wind etc.
On the Embraer V/S is not used. We use Flight Path Angle instead. But yes, you can use speedbrakes in both modes.
In v/s you are not speed protected so we tend to use Flight Level Change or FPA. In FPA you are also not speed protected. but it maintains a given descent angle irrespective of config/speed/wind etc.
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For such a clearance I recommend to use OP DES. If unable to meet the target V/S with THR IDLE mode active, then it is obvious that you need speedbrakes. Use them as required.
If you use V/S and SPEED mode is unable to maintain the target speed (actual speed is greater than target with the engines at idle), then it is obvious that you need speedbrakes. Physically you are doing the same, an idle descent with speedbrakes, but it is more intuitive and less confusing with the OP DES, in my opinion.
V/S is a great, great tool, however, that you can use in many situations. It allows you to tactically set the rate at which you change airplane speed. OP DES, DES, OP CLB and CLB modes include algorithms for acceleration and deceleration that depend on several factors. Sometimes they are not convenient for your particular situation and you can change that by using V/S mode. Also, V/S mode allows you a more direct control of your pitch attitude. It is like an indirect way of pulling or pushing the sidestick, so to speak. It is very useful when you have TCAS TA, to prevent a TCAS RA, for instance. If ALT* happens and you still want to use V/S because of that push to level off, then adjust the V/S.
Again, many pilots seem to be scared of using it. That is wrong. V/S is your friend, and it comes with a very good friend of its own: SPEED. And it has protections for excessive rates. What else could one ask for???
Don't forget that V/S is the pitch basic mode of the AP/FD and you must know how to use it. There are some things you have to bear in mind when using it, but nothing complicated.
If you use V/S and SPEED mode is unable to maintain the target speed (actual speed is greater than target with the engines at idle), then it is obvious that you need speedbrakes. Physically you are doing the same, an idle descent with speedbrakes, but it is more intuitive and less confusing with the OP DES, in my opinion.
V/S is a great, great tool, however, that you can use in many situations. It allows you to tactically set the rate at which you change airplane speed. OP DES, DES, OP CLB and CLB modes include algorithms for acceleration and deceleration that depend on several factors. Sometimes they are not convenient for your particular situation and you can change that by using V/S mode. Also, V/S mode allows you a more direct control of your pitch attitude. It is like an indirect way of pulling or pushing the sidestick, so to speak. It is very useful when you have TCAS TA, to prevent a TCAS RA, for instance. If ALT* happens and you still want to use V/S because of that push to level off, then adjust the V/S.
Again, many pilots seem to be scared of using it. That is wrong. V/S is your friend, and it comes with a very good friend of its own: SPEED. And it has protections for excessive rates. What else could one ask for???
Don't forget that V/S is the pitch basic mode of the AP/FD and you must know how to use it. There are some things you have to bear in mind when using it, but nothing complicated.
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VS and Speedbrake don't work very well together for the reasons stated above, the only reason to use this combination is if you were unusually assigned a particular RoD and were trying to get the speed back. If you PULL 250kt and PULL 2500 Vs, VS being a basic mode mode will have greater priority over SPEED mode and you will accelerate away from your selected speed target. This situation will continue until an overspeed occurs, when the OS protection will temporarily override the VS command and pitch the a/c up to maintain vmax. It is possible to use the speedbrake to prevent this, but it would look and feel untidy.
If ATC are being unreasonable with your 250kts/2500fpm scenario, you can consider:
taking the autopilot out which on most A320's allows maximum Speedbrake to pop out, instead of the just over 50% with Ap engaged, this works a treat. It does not work on A321's and other specific Airbuses, so check your MSN.
If you are really stuck and are quite close in to destination, state 'non standard' and get the gear down. This technique is completely appropriate and combined with the full speedbrake gives a very sporting Rod. But it requires a bit of the mental arithmetic that as discussed in a previous thread.
I make no claim to being a Airbus expert, so this just line stuff which I might use in a specific situation, that I know will work OK.
Good questions OP, keep 'em coming.
ps. once upon a time there used to be a breed of pilot that regarded it as a matter of honour that they didn't use the speedbrake ever and actually laughed at you if you did, thankfully this has largely died out.
If ATC are being unreasonable with your 250kts/2500fpm scenario, you can consider:
taking the autopilot out which on most A320's allows maximum Speedbrake to pop out, instead of the just over 50% with Ap engaged, this works a treat. It does not work on A321's and other specific Airbuses, so check your MSN.
If you are really stuck and are quite close in to destination, state 'non standard' and get the gear down. This technique is completely appropriate and combined with the full speedbrake gives a very sporting Rod. But it requires a bit of the mental arithmetic that as discussed in a previous thread.
I make no claim to being a Airbus expert, so this just line stuff which I might use in a specific situation, that I know will work OK.
Good questions OP, keep 'em coming.
ps. once upon a time there used to be a breed of pilot that regarded it as a matter of honour that they didn't use the speedbrake ever and actually laughed at you if you did, thankfully this has largely died out.
Last edited by macdo; 8th Jun 2012 at 19:39.
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I was barely taught to use speed brakes, and v/s etc on TR, and now on line I see a lot of captains playing around with v/s which is very new to me.
I understand that you shouldn't or wouldn rather not use v/s to increase rate of descent that often, because it could increase speed a lot, but you would rather use speed brakes, correct?
If finding yourself below profile, use it to reduce rate of descent, and it will continue to maintain speed with no problems?
Can you use speed brakes and v/s both together?
ATC asked you to descent at 2500 ft per minute and maintain 250 knots.
What happens if you speed select 250 and put v/s 2500?
I assume the v/s is the priority and speed is disregarded? In this case do you use speed brakes to slow down?
I understand that you shouldn't or wouldn rather not use v/s to increase rate of descent that often, because it could increase speed a lot, but you would rather use speed brakes, correct?
If finding yourself below profile, use it to reduce rate of descent, and it will continue to maintain speed with no problems?
Can you use speed brakes and v/s both together?
ATC asked you to descent at 2500 ft per minute and maintain 250 knots.
What happens if you speed select 250 and put v/s 2500?
I assume the v/s is the priority and speed is disregarded? In this case do you use speed brakes to slow down?
Use V/S whenever you want to maintain a specific V/S. Also use it to get down to G/S when intercepting from above.
Speedbrakes + V/S is a useful combination when you want to slow down while descending at a constant rate. If airspeed starts increasing when the throttles hit the idle stop in V/S, use the speedbrakes as necessary.
In the 744, V/S will sacrifice airspeed to maintain the selected V/S; there is no speed protection at the high or low end in V/S.
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On the Embraer V/S is not used. We use Flight Path Angle instead. But yes, you can use speedbrakes in both modes.
In v/s you are not speed protected so we tend to use Flight Level Change or FPA. In FPA you are also not speed protected. but it maintains a given descent angle irrespective of config/speed/wind etc.
In v/s you are not speed protected so we tend to use Flight Level Change or FPA. In FPA you are also not speed protected. but it maintains a given descent angle irrespective of config/speed/wind etc.
The trouble with FPA is, as in the scenario above, if you are trying to control ROD and speed but your speed starts to run away from you so will your VS. You're then in a bit of a vicious circle.
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Thank you all very much for the informative posts once again.
Definitely does make sense.
Line training captain today told me he personally never uses V/S to increase ROD generally because it disregards speed, but often uses it for a slow rate of climb for passenger comfort, and also to slow ROD when he finds himself below profile.
When using V/S to minimize rate of descent or climb, thrust will be added or reduced to maintain the manged speed, correct?
Also, since you bring it up intruder.
I have done it once in the sim only, intercepting GS from above.
Arm the approach, turn alt knob to be higher, select V/S -1500-2000 and pull.
Use speed brakes to help?
From what I have been told, the airbus is a pain to understand at first, but is a charm once you understand it.
Right now every captain I watch does something different. Some randomly seem to go on open climb, some manage, some would rather be low and slow, some high and somewhat fast, etc.
all in all it's an amazing aircraft I think.(not that I have much to compare it with
)
thanks for the responses guys!
Definitely does make sense.
Line training captain today told me he personally never uses V/S to increase ROD generally because it disregards speed, but often uses it for a slow rate of climb for passenger comfort, and also to slow ROD when he finds himself below profile.
When using V/S to minimize rate of descent or climb, thrust will be added or reduced to maintain the manged speed, correct?
Also, since you bring it up intruder.
I have done it once in the sim only, intercepting GS from above.
Arm the approach, turn alt knob to be higher, select V/S -1500-2000 and pull.
Use speed brakes to help?
From what I have been told, the airbus is a pain to understand at first, but is a charm once you understand it.
Right now every captain I watch does something different. Some randomly seem to go on open climb, some manage, some would rather be low and slow, some high and somewhat fast, etc.
all in all it's an amazing aircraft I think.(not that I have much to compare it with
)thanks for the responses guys!
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Originally Posted by zerozero
250kts & 2500fpm descent?
Sorry, sometimes you just have to say "unable".
Sorry, sometimes you just have to say "unable".
How's your new digs? You need to update your profile.
Last edited by A Squared; 9th Jun 2012 at 01:08.
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Originally Posted by A Squared
I can do that without speed brakes. Easy.
How's your new digs? You need to update your profile.
How's your new digs? You need to update your profile.
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Airbus has so many tools... Use them any time you see it fit to use them. If you are the Pilot Flying you have to fly the airplane. That can be full managed, almost full managed, partially managed, selected, AP OFF... As required by the situation and according to circumstances. You must never be flown by the airplane. Ignore those who tell you to manage everything every time.
If you don't like the V/S of your airplane, or the rate at which it is losing or gaining knots, or the rate at which it is pitching, or something, you are the pilot flying and have to make the airplane do what you want it to do.
For the time being, get familiar with the machine, understand it. Then study it again and you will see you didn't understand it so well, so study it again and understand it. Still, you have to study it a bit more... Learn from others, but always in a critical way (don't learn bad habits) and beware of negative training (lots of it can be poured into you if you are unlucky with the TRI, TREs...). With time, experience and a constant learning mentality, you will reach higher and higher levels of understanding and you will truly master the machine. Enjoy the process. After 10 years I still learn and I am sure there are still a few levels to reach.
If you don't like the V/S of your airplane, or the rate at which it is losing or gaining knots, or the rate at which it is pitching, or something, you are the pilot flying and have to make the airplane do what you want it to do.
For the time being, get familiar with the machine, understand it. Then study it again and you will see you didn't understand it so well, so study it again and understand it. Still, you have to study it a bit more... Learn from others, but always in a critical way (don't learn bad habits) and beware of negative training (lots of it can be poured into you if you are unlucky with the TRI, TREs...). With time, experience and a constant learning mentality, you will reach higher and higher levels of understanding and you will truly master the machine. Enjoy the process. After 10 years I still learn and I am sure there are still a few levels to reach.
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Think through the dynamics of what you want to achieve.
VS is useful for a controlled rate of descent, it is seldom, if ever the correct way to achieve a high RoD. I was taught (on 737) that VS is not a suitable mode with power in the lower quarter of the range, or close to the top as reaching idle or max thrust will begin to affect the speed, so in those thrust regimes use Level Change or whatever equivalent mode you are equipped with. Failure to observe this basic precaution will eventually lead to a speed exceedence at one end of the range or the other. If you need more RoD than can be achieved with idle thrust either increase IAS or maintain what you have and use speedbrake, or both, which is used depends again on the situation, ie is speed able to be varied?
Using speedbrake to increase RoD when higher speed is not a problem is a clumsy technique, but of course close to (or intercepting) the approach increasing speed is a good way to get yourself into a pickle.
I regard using speedbrake to slow the aircraft as clumsy too unless the reduction is urgent which is rare. It isn't intended to be used like the brakes on a car. We'd be better off referring to them by their proper name, "Spoilers" which is less likely to form slowing down associations in the minds of junior (and some senior) pilots.
As said elsewhere the gear is a useful and valid option close in too.
Finally, if you can't comply, tell ATC. They will have to give you a workable option, be it more miles, a turn, changing the clearance etc. That is up to them, and you can suggest what you can do as said above. It's your show, not theirs!
VS is useful for a controlled rate of descent, it is seldom, if ever the correct way to achieve a high RoD. I was taught (on 737) that VS is not a suitable mode with power in the lower quarter of the range, or close to the top as reaching idle or max thrust will begin to affect the speed, so in those thrust regimes use Level Change or whatever equivalent mode you are equipped with. Failure to observe this basic precaution will eventually lead to a speed exceedence at one end of the range or the other. If you need more RoD than can be achieved with idle thrust either increase IAS or maintain what you have and use speedbrake, or both, which is used depends again on the situation, ie is speed able to be varied?
Using speedbrake to increase RoD when higher speed is not a problem is a clumsy technique, but of course close to (or intercepting) the approach increasing speed is a good way to get yourself into a pickle.
I regard using speedbrake to slow the aircraft as clumsy too unless the reduction is urgent which is rare. It isn't intended to be used like the brakes on a car. We'd be better off referring to them by their proper name, "Spoilers" which is less likely to form slowing down associations in the minds of junior (and some senior) pilots.
As said elsewhere the gear is a useful and valid option close in too.
Finally, if you can't comply, tell ATC. They will have to give you a workable option, be it more miles, a turn, changing the clearance etc. That is up to them, and you can suggest what you can do as said above. It's your show, not theirs!
Last edited by Agaricus bisporus; 9th Jun 2012 at 08:55.
My view has always been that speedbrakes are there to be used when required.
Better to use judiciously than be too high or fast at a limit point.
One of the great things about command is knowing there will be no 'Tut, tutting.' from the LHS
Better to use judiciously than be too high or fast at a limit point.
One of the great things about command is knowing there will be no 'Tut, tutting.' from the LHS
I think Agaricus has some very valid points.
You *can* use V/S and speedbrake together but over the years I've observed that it requires more attention than other ways of getting the same result. Wind gradient, icing, config. and speed changes all need continuous adjustments in the amount of speedbrake.
If you're distracted by other duties or events, which normally happens during the approach phase when speedbrakes are needed, you can easily end up with power coming up against the spoilers or getting close to limiting speeds, especially with a significant V/S or flap deployed. Yes, if you're on top of it all, it can be managed without incident but, to me, it lacks... Elegance, or something close to that. I feel part of being professional is to try to leave as much spare capacity as possible to deal with unforeseen events (or even foreseen ones...), especially when in a busy environment.
All AFDSs that I know of prioritise V/S over anything else, so the speed will vary unless you keep a close eye on the instruments and move the lever around. In the terminal environment, ATC generally want you to fly constant speeds and vary the RoD, rather than the other way round. It's simpler just to use an open descent mode (level change in Boeings) and adjust your descent rate using more or less drag. This has the advantage that the aircraft is speed stable if you take your eye off the ball for a moment.
V/S is one of those modes that if used thoughtlessly or without due monitoring can put you in a situation you'd rather not be in, such as behind the drag curve at high altitude if you climb/descend into a decreasing headwind or increasing tailwind. Strong temperature gradients can produce unexpected results as engine power decreases along with mach number. Things like this occur because it is easy to set a V/S which is instantaneously OK but will sooner or later take the aircraft out of its performance and/or flight envelope.
You *can* use V/S and speedbrake together but over the years I've observed that it requires more attention than other ways of getting the same result. Wind gradient, icing, config. and speed changes all need continuous adjustments in the amount of speedbrake.
If you're distracted by other duties or events, which normally happens during the approach phase when speedbrakes are needed, you can easily end up with power coming up against the spoilers or getting close to limiting speeds, especially with a significant V/S or flap deployed. Yes, if you're on top of it all, it can be managed without incident but, to me, it lacks... Elegance, or something close to that. I feel part of being professional is to try to leave as much spare capacity as possible to deal with unforeseen events (or even foreseen ones...), especially when in a busy environment.
All AFDSs that I know of prioritise V/S over anything else, so the speed will vary unless you keep a close eye on the instruments and move the lever around. In the terminal environment, ATC generally want you to fly constant speeds and vary the RoD, rather than the other way round. It's simpler just to use an open descent mode (level change in Boeings) and adjust your descent rate using more or less drag. This has the advantage that the aircraft is speed stable if you take your eye off the ball for a moment.
V/S is one of those modes that if used thoughtlessly or without due monitoring can put you in a situation you'd rather not be in, such as behind the drag curve at high altitude if you climb/descend into a decreasing headwind or increasing tailwind. Strong temperature gradients can produce unexpected results as engine power decreases along with mach number. Things like this occur because it is easy to set a V/S which is instantaneously OK but will sooner or later take the aircraft out of its performance and/or flight envelope.
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Never fails to amaze me when I hear people critical of pilots who choose to use speedbrake. The reason it's there and certified for usage in flight is that it's an aerodynamic device that's part of the package.
Agaricus, try getting away with not using speedbrakes into lots of places around the world, and you'll find yourself embarressed.
On the Boeing, FLCH and speedbrake is a better way of maintaining a ROD and a speed that might be difficult to do otherwise. VS will have you still requiring speedbrake to keep the speed back, but you will find the thrust levers coming up in anticipation......and causing further embarrassment.
Agaricus, try getting away with not using speedbrakes into lots of places around the world, and you'll find yourself embarressed.
On the Boeing, FLCH and speedbrake is a better way of maintaining a ROD and a speed that might be difficult to do otherwise. VS will have you still requiring speedbrake to keep the speed back, but you will find the thrust levers coming up in anticipation......and causing further embarrassment.
Last edited by haughtney1; 9th Jun 2012 at 12:12.