TOP of descent, and descent monitoring. (A320)
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I agree with the above, just make sure the box has something realistic in it.
Then that is most economical way to fly, and is the SOP at my place.. To keep it updated and stay managed.
Then that is most economical way to fly, and is the SOP at my place.. To keep it updated and stay managed.
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Thank you all VERY much for the responses.
Lots of informative and useful posts.
Someone asked if its my first airline job, and to answer your question, yes it is.
At the moment being new to all of this. Not just the aircraft but also real world flying, would it work out fine for me if I just used the simple method of, altitude to lose X 3 plus 10. If my track miles are more than what I get from this simple formula, obviously I'm below profile, and if less track miles than calculated, I'm high.
In addition to that, I can Increase speed Or use speed breaks to descend lower, decrease speed to reduce V/S.
Would it be okay to use this simple method for now, not to complicate the whole scenario even more, as basically EVERYTHING is new to me at this point.
Also, yet another stupid question.
What is the difference if I increased V/S, or just ncreased speed.
I believe ncreasing V/S will increase speed as needed to give the V/S set.
Lots of informative and useful posts.
Someone asked if its my first airline job, and to answer your question, yes it is.
At the moment being new to all of this. Not just the aircraft but also real world flying, would it work out fine for me if I just used the simple method of, altitude to lose X 3 plus 10. If my track miles are more than what I get from this simple formula, obviously I'm below profile, and if less track miles than calculated, I'm high.
In addition to that, I can Increase speed Or use speed breaks to descend lower, decrease speed to reduce V/S.
Would it be okay to use this simple method for now, not to complicate the whole scenario even more, as basically EVERYTHING is new to me at this point.
Also, yet another stupid question.
What is the difference if I increased V/S, or just ncreased speed.
I believe ncreasing V/S will increase speed as needed to give the V/S set.
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Also, yet another stupid question.
What is the difference if I increased V/S, or just increased speed.
I believe increasing V/S will increase speed as needed to give the V/S set.
What is the difference if I increased V/S, or just increased speed.
I believe increasing V/S will increase speed as needed to give the V/S set.
The only other advice I would give you is to remember the effect of wind (see my post #4) particularly in calculating ToD - and it will change on the way down - and to always add on a 'bit for mum' in your early days (the first 5 or so sectors) by descending, say, 5 miles early, so you don't get 'high'. I'm sure a decent TC will not have an apoplexy
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Standard Airbus technique if HIGH on the profile as indicated by your magenta deviation 'donut' (yes i know its not a donut anymore on the latest revision of the fmgc, before anyone points it out!) is OPEN DESCENT and increase SELECTED SPEED, if you remain fully MANAGED, deploy 1/2 speedbreak in order to meet the 'rejoined profile' down arrow, either works fine, but the OPEN DES method is more decisive. If low then VS and SELECTED SPEED, (managed speed can be used, but some trainers like to see that you are accepting control over the FMGC by Selecting your speed as well as your RoD.) When back on the profile, go back to fully managed. The only time you really need to calculate the Distance vs Altitude is when on vectors and you have cleared the FMGC to only show the Approach from the Final (or Centr) fix to the GA point. The donut is still there to help you, but backing it up with some mental arithmetic is good.
The Airbus concept is smart aircraft for dumb pilots and largely you can use this philosophy safely to make your life easy, which suits me fine. BUT, what Airbus don't say on the tin is that buried away inside your clever aircraft are lots of traps for the unwary in the form of computer glitches and oddities of logic. Your mission is to be ahead of the aircraft and have a really good understanding to the FMGC and the automatics, cause if you don't some dark and stormy night your friendly Airbus will bite you on the backside.
The Airbus concept is smart aircraft for dumb pilots and largely you can use this philosophy safely to make your life easy, which suits me fine. BUT, what Airbus don't say on the tin is that buried away inside your clever aircraft are lots of traps for the unwary in the form of computer glitches and oddities of logic. Your mission is to be ahead of the aircraft and have a really good understanding to the FMGC and the automatics, cause if you don't some dark and stormy night your friendly Airbus will bite you on the backside.
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There are several reasons for a pilot of a 320 to be proficient in accurately calculating a TOD and monitoring a descent without the FMGS.
The first of them is the need to check the reasonableness of the FMGS predictions and indications.
It is very difficult to be proficient at that if you don't practice.
It also gives you independence, since sometimes it is be too complicated to set the lateral navigation with the MCDU. It is much better to carry out the descent (or typically a part of it) with selected modes.
Even for full descents. In many airports you are never going to fly the FMGC depicted FPLN. You may bet to one of several possibilities, but there is no use in changing all the FPLN just based one of those possibilities. It is better to base your descent in that possibility without major changes in the MCDU. You are betting on a given track and distance to go, which may be radically different to that in the MCDU. You have to make calculations of your own.
An example: flying to Dubai Intl 30L coming from the gulf, from northwest, the arrival takes you to the runway via a right downwind, a base and then final. There are many altitud restrictions so that you are quite low all throughout the arrival. Then, in final, many get high because they follow the donut. What a nonsense. Because if you are number one or two you are not going to fly All those miles. So what you do is: at your mentally calculated TOD for those miles you expect to fly, from say the 10,000 ft you are maintaining, you pull OP DES. When they give you the shortcut you are on profile. If you are on the donut, you are high so they don't give it to you altogether. This may save 2 minutes ore more. Of course, if there is a lot of traffic, you are number 6, just follow the donut, or even fly somewhat above it...
Optimizing takes some thinking. Efforts to avoid thinking are no good.
The first of them is the need to check the reasonableness of the FMGS predictions and indications.
It is very difficult to be proficient at that if you don't practice.
It also gives you independence, since sometimes it is be too complicated to set the lateral navigation with the MCDU. It is much better to carry out the descent (or typically a part of it) with selected modes.
Even for full descents. In many airports you are never going to fly the FMGC depicted FPLN. You may bet to one of several possibilities, but there is no use in changing all the FPLN just based one of those possibilities. It is better to base your descent in that possibility without major changes in the MCDU. You are betting on a given track and distance to go, which may be radically different to that in the MCDU. You have to make calculations of your own.
An example: flying to Dubai Intl 30L coming from the gulf, from northwest, the arrival takes you to the runway via a right downwind, a base and then final. There are many altitud restrictions so that you are quite low all throughout the arrival. Then, in final, many get high because they follow the donut. What a nonsense. Because if you are number one or two you are not going to fly All those miles. So what you do is: at your mentally calculated TOD for those miles you expect to fly, from say the 10,000 ft you are maintaining, you pull OP DES. When they give you the shortcut you are on profile. If you are on the donut, you are high so they don't give it to you altogether. This may save 2 minutes ore more. Of course, if there is a lot of traffic, you are number 6, just follow the donut, or even fly somewhat above it...
Optimizing takes some thinking. Efforts to avoid thinking are no good.
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WsT
Firstly, your instructor is trying to teach you how to manage the descent on your own. It is very seldom that you will fly an entirely managed descent in todays ATC environment. Vectors are a very important tool in the ATCs armoury and then you will need to know how the aircraft is performing wrt the descent. Take heed of his lessons, he is doing you a favour.
Secondly, despite some peoples reverence for the FMGS, it is not the most efficient way to manage a descent, especially in an A320 with IAE engines. It is very conservative(for good reason) and you will often find yourself low and having to intervene with V/S. A point to remember is that while V/S can be helpful, you lose a lot of protections and therefore it is not the best way to descend for extended periods of time.
As to being high, remember your Aero-d lectures/lessons. The co-eff of drag, like that of lift is depend on the speed of the a/c. Therefore, the higher the speed, the more the drag and the quicker you will descend resulting in a requirement for less distance for the high speed descent.
Finally, and for me personally the most important, is that it is more fun to manage your own descent and therefore the most fulfilling. Not much(from a work point of view) beats the feeling of idle from TOD to stable at 1000'(which I have to admit, doesn't happen all that often but I do try).
Firstly, your instructor is trying to teach you how to manage the descent on your own. It is very seldom that you will fly an entirely managed descent in todays ATC environment. Vectors are a very important tool in the ATCs armoury and then you will need to know how the aircraft is performing wrt the descent. Take heed of his lessons, he is doing you a favour.
Secondly, despite some peoples reverence for the FMGS, it is not the most efficient way to manage a descent, especially in an A320 with IAE engines. It is very conservative(for good reason) and you will often find yourself low and having to intervene with V/S. A point to remember is that while V/S can be helpful, you lose a lot of protections and therefore it is not the best way to descend for extended periods of time.
As to being high, remember your Aero-d lectures/lessons. The co-eff of drag, like that of lift is depend on the speed of the a/c. Therefore, the higher the speed, the more the drag and the quicker you will descend resulting in a requirement for less distance for the high speed descent.
Finally, and for me personally the most important, is that it is more fun to manage your own descent and therefore the most fulfilling. Not much(from a work point of view) beats the feeling of idle from TOD to stable at 1000'(which I have to admit, doesn't happen all that often but I do try).
A good example would be Larnaca in Cyprus rwy 22, where you can easily let the FMGC fly from top of drop on the STAR to short final on the ILS with no intervention
I assume you mostly use the Daros 2A, then that would make sense. Chaos corner, indeed.
Try any other arrival into LCA and the boxes profile goes out of the window.
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As you say, Daros2a works a treat, you just have to watch out for the altitude restriction at SOLAB as sometimes it is not coded and must be entered manually. This was my best example. The only reason this sticks in my mind is because years ago I had a bet with a skipper who said he could get the a/c to fly the whole thing from Tombo fully managed and I was a' doubting thomas! I lost the bet. At the time, as a new boy, i was keen to intervene at every point, but I now know that Managed flying on the 'bus is the most efficient way to operate it. I absolutely agree that you have got to be able to do all the mental gymnastics, but that is not the Airbus philosophy. For the new guy who started this thread, he should have already proved that he can do the mental arithmetic in a Seneca or something, and again IMHO, if I were a trainer I would be much more impressed with a deep understanding of the aircraft automation, than any ability to operate the a/c without it.
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There is a generation conflict here.
For the "veterans", automation looks like a very complex thing that achieves magically things that otherwise take a lot of mental work. So they do every effort to understand automation and the interface. They have flown manual or with old automation systems more than enough.
For the "freshmen", automation is a very simple thing (later they will learn it is not so simple, but it is just another computer in their life) and they won't even know what task the automation is relieving the pilot from if they never perform it on their own. They didn't have the opportunity.
In the Senecas, the mental gymnastics are different. I think that we must master both sides of the coin: brain and computer. Playing too much can lead to inefficiency or even trouble. Relying on automation too much can lead to that, too.
A classical example: you are cruising at FL 340 and ATC gives you an early constraint at say, FL 290 well away or the airport. If you just put the constraint and at the TOD manage the descent, then the airplane will do a nasty idle descent at 3,000 fpm and then capture 290, with the associated thrust increase. Instead, a simple math calculation and the use of V/S achieves a far better way of doing the job. Some make it even worse, they manage the descent well before the TOD, so they get 1,000 fpm. That's fine, but then the flight path captures the profile at maybe 1,500 ft above FL 290 and the airplane all of a sudden goes idle, pitches down, reaches 3,000 fpm, ALT *, pitch up again, N1 increasing rapidly again... So untidy!
I apply the automation rule (using the level of automation required for the task and conditions). For too many this rule is: "use highest automation level no matter what, except if you loose the automation" which makes no sense.
Airbus automation is very good and I like it very much. I trust it because I know it intimately and I know that if one day I need the computer to manage for me while I have to deal with some kind of emergency or situation I can rely on it.
For the "veterans", automation looks like a very complex thing that achieves magically things that otherwise take a lot of mental work. So they do every effort to understand automation and the interface. They have flown manual or with old automation systems more than enough.
For the "freshmen", automation is a very simple thing (later they will learn it is not so simple, but it is just another computer in their life) and they won't even know what task the automation is relieving the pilot from if they never perform it on their own. They didn't have the opportunity.
In the Senecas, the mental gymnastics are different. I think that we must master both sides of the coin: brain and computer. Playing too much can lead to inefficiency or even trouble. Relying on automation too much can lead to that, too.
A classical example: you are cruising at FL 340 and ATC gives you an early constraint at say, FL 290 well away or the airport. If you just put the constraint and at the TOD manage the descent, then the airplane will do a nasty idle descent at 3,000 fpm and then capture 290, with the associated thrust increase. Instead, a simple math calculation and the use of V/S achieves a far better way of doing the job. Some make it even worse, they manage the descent well before the TOD, so they get 1,000 fpm. That's fine, but then the flight path captures the profile at maybe 1,500 ft above FL 290 and the airplane all of a sudden goes idle, pitches down, reaches 3,000 fpm, ALT *, pitch up again, N1 increasing rapidly again... So untidy!
I apply the automation rule (using the level of automation required for the task and conditions). For too many this rule is: "use highest automation level no matter what, except if you loose the automation" which makes no sense.
Airbus automation is very good and I like it very much. I trust it because I know it intimately and I know that if one day I need the computer to manage for me while I have to deal with some kind of emergency or situation I can rely on it.
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TOD to APP
Sorry, if thread spread, am avidly reading all your posts to check if this has been answered -
actually, I have a Question.
don`t care if openeing myself up to criticism but:
I know I should know this, but suddenly have forgotten it - notwithstanding Alzheimers, or even spelling . . If at TOD I shall avoid all FMA and PFD checks for this scenario - (God this is so simple)
you are just before TOD say, and everything not mentioned here has been done . .
You set up a lower FL say FL170 and push and down you go,
If, if you select speed 280 say, then the descent is still managed but the speed is not.
A/P is still engaged.
A/Th is still in, (at work will get back to you )- anyway, will not the a/c manage the descent, except that your in Selected Spd and the descent will be managed as the aircraft tries to maintain the profile using pwr + att .
actually, I have a Question.
don`t care if openeing myself up to criticism but:
I know I should know this, but suddenly have forgotten it - notwithstanding Alzheimers, or even spelling . . If at TOD I shall avoid all FMA and PFD checks for this scenario - (God this is so simple)
you are just before TOD say, and everything not mentioned here has been done . .
You set up a lower FL say FL170 and push and down you go,
If, if you select speed 280 say, then the descent is still managed but the speed is not.
A/P is still engaged.
A/Th is still in, (at work will get back to you )- anyway, will not the a/c manage the descent, except that your in Selected Spd and the descent will be managed as the aircraft tries to maintain the profile using pwr + att .
Last edited by Natstrackalpha; 7th Jun 2012 at 11:52. Reason: Just, tidying it up
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Managed descent with selected speed, another untidy thing except if you are high on profile at a high speed. When on profile with a selected speed similar to ECON speed, SPEED and THR IDLE modes will alternate annoyingly.
If you select a low speed, you will get high. If you select a high speed, SPEED mode will keep the high speed an pitch will keep the profile, but... If speed is much higher, airplane energy is much higher too, and if you don't pull for an OP DES early enough, in the end you will have to use speedbrakes! That's another classic, by the way. I have seen it happen many times, as follows:
ATC clears us to a mid flight level, such as FL240, well away from arrival airport. Then pilot selects FL240 as the cruising FL, so you have a TOD in the MCDU. Pooblem is that ECON speeds will change and ECON descent speed may be quite slow, like 265 or something. So when reaching the TOD, the pilot pushes for DES and when realising speed is too slow he selects, say 320 knots (he wants to arrive early for supper).
Pitch will maintain the magenta profile, which is calculated for a 265 knots idle descent. SPEED mode increases thrust very noticeably to maintain that shallow path at 320 knots. Pilot requests "high speed below ten". Everything seems alright. Then there is a moment where the pilot, being on profile at, say, 20 miles, starts deceleration and then something smells rotten and the pilot deploys speedbrakes. Finally he manages to do the ILS only it took early configuration and speedbrakes all the way. Why? Because he had about 70 extra knots of energy. The profile was never good. He was never on profile. He has been using thrust all throughout the descent and at the end he had to use speedbrakes and early flaps, maybe even early gear down depending on the particular circumstances of the day.
These mistakes stem from two added factors:
incomplete knowledge of the airplane's managed automation plus lack of knowledge of the airplane performance and behaviour without the managed modes and without automation at all.
Both are unacceptable. Pilots must master both skills: managed and selected automation and manual flight.
If you select a low speed, you will get high. If you select a high speed, SPEED mode will keep the high speed an pitch will keep the profile, but... If speed is much higher, airplane energy is much higher too, and if you don't pull for an OP DES early enough, in the end you will have to use speedbrakes! That's another classic, by the way. I have seen it happen many times, as follows:
ATC clears us to a mid flight level, such as FL240, well away from arrival airport. Then pilot selects FL240 as the cruising FL, so you have a TOD in the MCDU. Pooblem is that ECON speeds will change and ECON descent speed may be quite slow, like 265 or something. So when reaching the TOD, the pilot pushes for DES and when realising speed is too slow he selects, say 320 knots (he wants to arrive early for supper).
Pitch will maintain the magenta profile, which is calculated for a 265 knots idle descent. SPEED mode increases thrust very noticeably to maintain that shallow path at 320 knots. Pilot requests "high speed below ten". Everything seems alright. Then there is a moment where the pilot, being on profile at, say, 20 miles, starts deceleration and then something smells rotten and the pilot deploys speedbrakes. Finally he manages to do the ILS only it took early configuration and speedbrakes all the way. Why? Because he had about 70 extra knots of energy. The profile was never good. He was never on profile. He has been using thrust all throughout the descent and at the end he had to use speedbrakes and early flaps, maybe even early gear down depending on the particular circumstances of the day.
These mistakes stem from two added factors:
incomplete knowledge of the airplane's managed automation plus lack of knowledge of the airplane performance and behaviour without the managed modes and without automation at all.
Both are unacceptable. Pilots must master both skills: managed and selected automation and manual flight.
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Cool, thanks for that. Really.
and . . point taken. (I thought I had . ., obviously not . .back to school, back to basics!)
Many thanks Microburst.
N.
================================
6 hours later: Ok, this is the situation . . .
The figures as above BUT - Start from ToD as per usual in managed, obviously go to spd from machno when appropriate. At the intermediate approach and subject to (because of) ATC then use Selected if necessary and depending largely on HWC or TWC or no wind, then . . use the firgures for 12 miles , 8, miles and 6 miles as above, "I did it myyyy way . " (joke) - Managed is good. Selected is more dans les mans (my French is c--p unlike my flying).
And . . on a slightly lighter note and with full consideration of those very responsible noise abatement people . . .would it not be better for eagle to be slightly high and sail it in, rather than bang on and drag it in . . hmmm? Also - and I mean this lovingly(within reason)) where is the premium on not being high and fast-ish? What is wrong with a bit of speebrake and early flaps / gear to slow - or were we already communicating . . .? . . hmmm?
I mean, on profile City is where I would like to be, but if have been reading some of the greats (like your good selves, most honourable gentle persons) and they are giving me speds like above, then it all must be happiness?
and . . point taken. (I thought I had . ., obviously not . .back to school, back to basics!)
Many thanks Microburst.
N.
================================
6 hours later: Ok, this is the situation . . .
The figures as above BUT - Start from ToD as per usual in managed, obviously go to spd from machno when appropriate. At the intermediate approach and subject to (because of) ATC then use Selected if necessary and depending largely on HWC or TWC or no wind, then . . use the firgures for 12 miles , 8, miles and 6 miles as above, "I did it myyyy way . " (joke) - Managed is good. Selected is more dans les mans (my French is c--p unlike my flying).
And . . on a slightly lighter note and with full consideration of those very responsible noise abatement people . . .would it not be better for eagle to be slightly high and sail it in, rather than bang on and drag it in . . hmmm? Also - and I mean this lovingly(within reason)) where is the premium on not being high and fast-ish? What is wrong with a bit of speebrake and early flaps / gear to slow - or were we already communicating . . .? . . hmmm?
I mean, on profile City is where I would like to be, but if have been reading some of the greats (like your good selves, most honourable gentle persons) and they are giving me speds like above, then it all must be happiness?
Last edited by Natstrackalpha; 7th Jun 2012 at 16:02.
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5 x 3 =15 but 15 x 3 = 45
Microburst
Ok, your mention of too high is not really high in my book at 15 miles, its only 425 feet and at 15 miles 425 feet above profile does not seem all that much, or maybe I`m wrong. Having said that, 3xheight for range is good down to 10,000 say, and then you can back calc 3xrange for height
Your comments on Open descent are as you suggested most favourable, I am still happy with 33 miles at FL100 notwithstanding alt constraint or spd constraint,
I would be looking for Green Dot or 210 at about 12 miles out or 8 miles if making an abeam approach, at 280 kts decelling to 250.
Eng Anti-Ice Off would give me some cool gates, thus:-
33 miles 10,000 280 max clean
20 miles 6000 250 clean
12 3800 210 or Green Dot Flap 1
8 .2500 180 or S speed Flap 1
4.5...1500 160 or F speed Flap 2 or 3 plus Gear.
Times to reduce speed are 350-210 2 mins 10 secs Dist 10 NM
===================350-280 1 min 6 NM
===================280-210 1 min 10 secs 4 NM
Using speedbrakes to aid decell will reduce these times by approximately 40% deployed and retracted gently. ADDED LATER ON: also the slight pitch up tendency due to speedbrake may help to decell more effectively but brisk speedbrake retraction may cause a pitch down and potential altitude bust.
I also favour the constant power technique, but that is for another day.
Ok, your mention of too high is not really high in my book at 15 miles, its only 425 feet and at 15 miles 425 feet above profile does not seem all that much, or maybe I`m wrong. Having said that, 3xheight for range is good down to 10,000 say, and then you can back calc 3xrange for height
Your comments on Open descent are as you suggested most favourable, I am still happy with 33 miles at FL100 notwithstanding alt constraint or spd constraint,
I would be looking for Green Dot or 210 at about 12 miles out or 8 miles if making an abeam approach, at 280 kts decelling to 250.
Eng Anti-Ice Off would give me some cool gates, thus:-
33 miles 10,000 280 max clean
20 miles 6000 250 clean
12 3800 210 or Green Dot Flap 1
8 .2500 180 or S speed Flap 1
4.5...1500 160 or F speed Flap 2 or 3 plus Gear.
Times to reduce speed are 350-210 2 mins 10 secs Dist 10 NM
===================350-280 1 min 6 NM
===================280-210 1 min 10 secs 4 NM
Using speedbrakes to aid decell will reduce these times by approximately 40% deployed and retracted gently. ADDED LATER ON: also the slight pitch up tendency due to speedbrake may help to decell more effectively but brisk speedbrake retraction may cause a pitch down and potential altitude bust.
I also favour the constant power technique, but that is for another day.
Last edited by Natstrackalpha; 12th Jun 2012 at 14:03.
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15 miles at 5,000 and 250 you are high, unless very light and/or strong headwind. That is how you would be with a FLx3 rule.
Anyway, I always prefer to calculate parting from my present altitude, speed and configuration. Distance to go is not clear every time and a don't need gates or specific sets of conditions.
I must say that most of the times, when FMGS FPLN is what I actually fly, my rule takes me with the donut. Only if conditions are special (weight and wind, basically) I deviate from that.
Anyway, I always prefer to calculate parting from my present altitude, speed and configuration. Distance to go is not clear every time and a don't need gates or specific sets of conditions.
I must say that most of the times, when FMGS FPLN is what I actually fly, my rule takes me with the donut. Only if conditions are special (weight and wind, basically) I deviate from that.
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Hi WST,
Iīm in a similar situation as you and if I could, from my inexperience, recommend you something is to memorize (or write down and use in flight until memorized) the gates given above by NTA. It gives distances, altitudes AND speeds + config.
It helps A LOT. Later for sure you (and I hopefully) will get to the finer details also described in this very interesting thread, but this numbers will help you for now.
One other thing, yes, there is a direct relationship between V/S and speed. Modifying one will affect the other. Which one to use? I guess it is something up to each individual BUT I got an advice from a TC which for now I will keep and basically goes about using Selected Speed below 10,000 and not the V/S. Why? because that way you are sure you will not bust any speed limit.
Say you are doing 240 decending thorugh 6000, using V/S, then you get some vectors, now all of the sudden you are high... no problem, increase V/S and thatīs it BUT then speed starts to creep up and suddenly you are doing say 255 AND already below 5000ft. NOT GOOD.
On the other hand, if in the same scenario you are using Selected Speed and then suddenly you are high, what would you do? Maybe think to increase speed, but then you will notice you are selecting (or about to select) something above the speed limit, and then you choose to use some speed brakes instead till on profile again.
I know it might sound basic for the more experienced but it does work, at least for me.
Then, just check the limits as: 250 below 10000, 230 near the Terminal area, and then, once you are getting closer to intercept, or turn base (if on vectors) select 2 or 3 knots below VFE next and keep it there. Why? Letīs say you thought you where going to get longer vectors, suddenly they turn you to intercept... if you are ALREADY in a safe speed (VFEnext -3): manage speed, request FLAP1 + GEAR DOWN and the speed will come back quickly and all will remain under control. But, if you have to wait for the speed to come back to VFEnext, and then start to configure to slow down and at the same time you want to get lower
specially with tailwnd it might be a bit too late.
Other thing I learned (the hard way
): sometimes itīs better to accept to be high for a brief period of time in order to be able to regain the profile. This applies to being left high by ATC close to the airfield. You might want to regain as usual with increasing speed, well, chances are you might not make it in the given distance, this increasing speed technique works better when FAR from the airfield. And anyway if you manage to do it (by increasing speed close to the airfield), as it has been pointed before, you will still have a lot of extra energy to get rid of in the form of speed. To prevent this situation it might be better to accept from the beginning that you will be high, SLOW DOWN (which will make you be even higher) and the put FLAP 1 GEAR and FLAP 2. If you manage to do this the airplane will sink very nice without any speed problems.
just my 2 cents (anyone please feel free to add correct any point)
Iīm in a similar situation as you and if I could, from my inexperience, recommend you something is to memorize (or write down and use in flight until memorized) the gates given above by NTA. It gives distances, altitudes AND speeds + config.
It helps A LOT. Later for sure you (and I hopefully) will get to the finer details also described in this very interesting thread, but this numbers will help you for now.
One other thing, yes, there is a direct relationship between V/S and speed. Modifying one will affect the other. Which one to use? I guess it is something up to each individual BUT I got an advice from a TC which for now I will keep and basically goes about using Selected Speed below 10,000 and not the V/S. Why? because that way you are sure you will not bust any speed limit.
Say you are doing 240 decending thorugh 6000, using V/S, then you get some vectors, now all of the sudden you are high... no problem, increase V/S and thatīs it BUT then speed starts to creep up and suddenly you are doing say 255 AND already below 5000ft. NOT GOOD.
On the other hand, if in the same scenario you are using Selected Speed and then suddenly you are high, what would you do? Maybe think to increase speed, but then you will notice you are selecting (or about to select) something above the speed limit, and then you choose to use some speed brakes instead till on profile again.
I know it might sound basic for the more experienced but it does work, at least for me.
Then, just check the limits as: 250 below 10000, 230 near the Terminal area, and then, once you are getting closer to intercept, or turn base (if on vectors) select 2 or 3 knots below VFE next and keep it there. Why? Letīs say you thought you where going to get longer vectors, suddenly they turn you to intercept... if you are ALREADY in a safe speed (VFEnext -3): manage speed, request FLAP1 + GEAR DOWN and the speed will come back quickly and all will remain under control. But, if you have to wait for the speed to come back to VFEnext, and then start to configure to slow down and at the same time you want to get lower
specially with tailwnd it might be a bit too late.Other thing I learned (the hard way
): sometimes itīs better to accept to be high for a brief period of time in order to be able to regain the profile. This applies to being left high by ATC close to the airfield. You might want to regain as usual with increasing speed, well, chances are you might not make it in the given distance, this increasing speed technique works better when FAR from the airfield. And anyway if you manage to do it (by increasing speed close to the airfield), as it has been pointed before, you will still have a lot of extra energy to get rid of in the form of speed. To prevent this situation it might be better to accept from the beginning that you will be high, SLOW DOWN (which will make you be even higher) and the put FLAP 1 GEAR and FLAP 2. If you manage to do this the airplane will sink very nice without any speed problems.just my 2 cents (anyone please feel free to add correct any point)
Last edited by RunSick; 10th Jun 2012 at 21:20.
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Then we would be sleeping durong descent!
I like the uncertainties. That makes the descent more fun. Within reason, of course. I hate when they change runway or pricedure or sequence every two minutes, like in some airports I know...
I like the uncertainties. That makes the descent more fun. Within reason, of course. I hate when they change runway or pricedure or sequence every two minutes, like in some airports I know...
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If I am descending on profile in Des mode and in managed speed; and now I select a speed lower than the managed speed (while keeping in Des mode), would the aircraft actually disregard the selected speed and continue to be on profile or would it end up high because it'll reduce the pitch to slow down?
New on the Airbus as well and never actually got to try this.
New on the Airbus as well and never actually got to try this.