Ground Speed Mini and Strong Headwinds
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Ground Speed Mini and Strong Headwinds
Just wondering if any of you have a company policy or sop for dealing with landing in strong headwinds circa 60-65 knots.
When in managed speed the ground speed mini function often commands a fly speed at or above the flap limiting speeds. Obviously selected speed will allow fly speeds just below the limits,but I was wondering if there are any other ideas out there. Thanx
When in managed speed the ground speed mini function often commands a fly speed at or above the flap limiting speeds. Obviously selected speed will allow fly speeds just below the limits,but I was wondering if there are any other ideas out there. Thanx
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G/S Mini limits the speed to Vfe config full minus 5kts so that should not be a problem. It is also worth remembering that it is not the surface wind that is the problem, it is in effect the difference between the wind affecting the ac on approach and the surface (tower) wind as entered in the Perf App Page which G/S Mini acts upon. Keep the tower wind up to date.
Cheers
mcdhu
Cheers
mcdhu
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Thanx Lads.
Following on above then.
Assuming 65kt headwind at 2500ft, reducing mainly in the last 1000ft to say 20kt down the runway. Would you be happy enough to leave the auto thrust in or out? Also assuming tower winds updated in mcdu as mentioned above.
Following on above then.
Assuming 65kt headwind at 2500ft, reducing mainly in the last 1000ft to say 20kt down the runway. Would you be happy enough to leave the auto thrust in or out? Also assuming tower winds updated in mcdu as mentioned above.
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G speed mini
It happened to me once during an app in Buenos Aires( SAEZ).What made me feel unconfortable was the fact the Fcom's don't say anything about it.
I used selected speed through flaps full, then went back to managed.
If you find it in writing let me know.
Good flights to you all.
Fbwdude
I used selected speed through flaps full, then went back to managed.
If you find it in writing let me know.
Good flights to you all.
Fbwdude
You don't say which Airbus you are flying but on the A340 in those conditions I find that using Config 3 for landing gives better handling. Using managed speed has always worked well.
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G/S Mini limits the speed to Vfe config full minus 5kts so that should not be a problem
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I find it way better at that point when the ground speed mini is enourmous to leave it in, but DISCONNECT the auto throttles and hand fly the approach at a more reasonable speed (DO NOT SELECT THE MORE RESONABLE SPEED). Fly your aircraft and use the ground speed mini as a warning that you are going to need to increase power.
YOU can increase power way faster than the auto throttles can. and before you start whinging about it being unsafe, ALPHA FLOOR is still available and you will also get the "Speed Speed" warnings if you are projected to be too slow in a few seconds, again giving you the chance to push up the throttles. IF you have lost the ability to do both fly the airplne and the throttles, then leave the auto pilot hooked up and focus on the speed.
Ground speed mini is a nice idea, but the real reason it was created is that the auto throttles are too slow, and with the fixed throttles you have no ability to help them out.
Selecting a speed is definately a bad idea, so if ATC is forcing you slower than ground speed mini, u are just going to have to do it the old fashioned way.
Cheers
Wino
YOU can increase power way faster than the auto throttles can. and before you start whinging about it being unsafe, ALPHA FLOOR is still available and you will also get the "Speed Speed" warnings if you are projected to be too slow in a few seconds, again giving you the chance to push up the throttles. IF you have lost the ability to do both fly the airplne and the throttles, then leave the auto pilot hooked up and focus on the speed.
Ground speed mini is a nice idea, but the real reason it was created is that the auto throttles are too slow, and with the fixed throttles you have no ability to help them out.
Selecting a speed is definately a bad idea, so if ATC is forcing you slower than ground speed mini, u are just going to have to do it the old fashioned way.
Cheers
Wino
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Fly 3:
I find as a previous poster has said on another thread that selecting Conf Full requires a higher thrust setting due to the increased drag and that the engines seem a little more responsive that at Conf 3.
Wino as Dreamland has said :
G/S Mini limits the speed to Vfe config full minus 5kts so that should not be a problem however the reality is different in certain conditions. I was suggesting selected speed to avoid flap exceedances NOT for the whole approach. ie back to managed once the condition has passed.
Thanx for the thoughts people!!
Safe Flying
I find as a previous poster has said on another thread that selecting Conf Full requires a higher thrust setting due to the increased drag and that the engines seem a little more responsive that at Conf 3.
Wino as Dreamland has said :
G/S Mini limits the speed to Vfe config full minus 5kts so that should not be a problem however the reality is different in certain conditions. I was suggesting selected speed to avoid flap exceedances NOT for the whole approach. ie back to managed once the condition has passed.
Thanx for the thoughts people!!
Safe Flying
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punchus, no, you may have misread, I have personally seen gs mini above 177 knots when in config full, not exactly how it is described in the books, same as Wino described.
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I'm assuming people are talking about A320 family and not the bigger buses
DL
If you are sure that you were in config F at the time I would suggest that the aircraft's FMGC possibly had a software glitch. G/S mini is limited to Vfe next in Config 1, 2 and 3 and Vfe-5kts in config F. That is, the Vapp target is limited, not the actual speed. Not the same thing. In very gusty conditions it is possible for the ATHR to get out of phase with the actual speed variations as the Vapp target, modified by G/S mini, can lag events somewhat.
Wino
I'm curious to know why you think going "selected" is a bad idea. I've been doing it when I think I need to in gusty conditions for as long as I have been flying A320s (9 years). Most of the time I'd go back to "managed" once out of the rough winds but occasionally it is better to stay selected all the way to the flare, especially if landing on a very short runway. At least the speed target is not moving so there is less chance of a prolonged flare and deep touchdown.
DL
I have personally seen gs mini above 177 knots when in config full, not exactly how it is described in the books,
Wino
I'm curious to know why you think going "selected" is a bad idea. I've been doing it when I think I need to in gusty conditions for as long as I have been flying A320s (9 years). Most of the time I'd go back to "managed" once out of the rough winds but occasionally it is better to stay selected all the way to the flare, especially if landing on a very short runway. At least the speed target is not moving so there is less chance of a prolonged flare and deep touchdown.
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Selected is a bad idea because it defeats the whole purpose of groundspeed mini (which is a constant GROUNDSPEED approach).
The reason that was created is because the autothrottles are not fast enough for all conditions and cannot be "helped" out like you could in brand B... There are situations where the aircraft will completely unspool itself. Groundspeed mini guarantees you enough smash to survive it. Selected speed does not.
But manually running the throttles will allow you to pull em towards closed but not completely closed, so you are still spooled...
I will fly my 140ish approach speed instead of the 170 groundspeed mini is commanding and be ready with a whole handfull of throttle knowing that I got 30 knots that are about to disappear somewhere.
So the groundspeed mini depiction of target airspeed is not my target. My target is the 140 ish or so I am looking for. Groundspeed mini becomes my psychic advisor of whats about to happen. Airplane stays at a more or less constant airspeed. Much less trimming going on, engines always spooled etc...
Selected speed with autothrottles in use is just defeating a safety feature that airbus felt you had to have because of the way they designed the autothrottle system.
Cheers
Wino
The reason that was created is because the autothrottles are not fast enough for all conditions and cannot be "helped" out like you could in brand B... There are situations where the aircraft will completely unspool itself. Groundspeed mini guarantees you enough smash to survive it. Selected speed does not.
But manually running the throttles will allow you to pull em towards closed but not completely closed, so you are still spooled...
I will fly my 140ish approach speed instead of the 170 groundspeed mini is commanding and be ready with a whole handfull of throttle knowing that I got 30 knots that are about to disappear somewhere.
So the groundspeed mini depiction of target airspeed is not my target. My target is the 140 ish or so I am looking for. Groundspeed mini becomes my psychic advisor of whats about to happen. Airplane stays at a more or less constant airspeed. Much less trimming going on, engines always spooled etc...
Selected speed with autothrottles in use is just defeating a safety feature that airbus felt you had to have because of the way they designed the autothrottle system.
Cheers
Wino
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Selected speed with autothrottles in use is just defeating a safety feature that airbus felt you had to have because of the way they designed the autothrottle system.
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different approach
what if in such a situation try to ride 1/2 a dot above the glide so the increased rod will compensate for the speed and at 1000 feet get back to normal glide? is it possible? will it work?
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UM, no that wouldn't work and would be grounds for a go around at many airlines...
Wingswinger,
I think we are actually arguing the same thing in many ways. By hand flying it, I am slower than I would have been in ground speed mini, leading to the more accurate touchdown.
Have seen very very high target speeds with groundspeed mini engaged on the autothrottles leading to just what you descibed (long landings, dithering around a couple of feet above the pavement for extended times etc...)
Cheers
Wino
Wingswinger,
I think we are actually arguing the same thing in many ways. By hand flying it, I am slower than I would have been in ground speed mini, leading to the more accurate touchdown.
Have seen very very high target speeds with groundspeed mini engaged on the autothrottles leading to just what you descibed (long landings, dithering around a couple of feet above the pavement for extended times etc...)
Cheers
Wino
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Wino
For which a good remedy to have in your shot-locker is to fly the approach manually as you describe, in selected speed. I prefer that because I then have a speed target displayed on the PFD which I am aiming for rather than deliberately ignoring the moving, G/S mini-ruled, Vapp target. With the thrust set manually at N1=GW-6%, TL adjustments do not need to be large and are usually of short duration. The aircraft rides the gusts well.
I must stress that I am talking only about approaches in strong gusty winds and their associated low-level turbulence, not about approaches in conditions in which a genuine windshear could be encountered (as opposed to gusts of +/-10 to 15kts, for example).
(long landings, dithering around a couple of feet above the pavement for extended times etc...)
I must stress that I am talking only about approaches in strong gusty winds and their associated low-level turbulence, not about approaches in conditions in which a genuine windshear could be encountered (as opposed to gusts of +/-10 to 15kts, for example).
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Have seen very very high target speeds with groundspeed mini engaged on the autothrottles leading to just what you descibed (long landings, dithering around a couple of feet above the pavement for extended times etc...)
'High Targetspeeds' are there for a reason! If you experience a 'sharp' speed-loss-windshear close to the ground (i.e. temp-inversion/high-pressure, pretty common here in fall/winter) YOU may be able to advance the TLs quick, but that won't help because of the time it takes THE AIRCRAFT to regain the lost speed beause of it's inertia.
The GS mini function was 'paid for' with blood, sweat and tears, can't believe anybody intentionally flying selected during a handflown app. only to get the speed down!
For those who don't know or remember 'the old times' before GS mini, here's an interesting transcript of the report on the A320 Accident at Warsaw (without GS mini). http://www.rvs.uni-bielefeld.de/publ...aw-report.html (if anybody knows a link to the 'official' report, I'd appreciate that)
I fully agree that the airbus is not the best aircraft for stormy approaches and that GS mini has it's disadvantages, too. But overall it's cleary a benefit and my company manuals don't allow selected speed during 'normal' approaches.
Manual Flight/Thrust and managed speed will do it, if the target is too high, either the wind-data on the PERF APP page are not accurate or your ADIRUs could need a re-alignment.
Regards, MAX
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Max,
I don't think G/S mini would have prevented the WAW crew from going off the end of RW11. They approached fast (+20kts IAS) with a tailwind well beyond limits (18 kts at touchdown) to a wet runway in heavy rain. They did not select autobrake either. There you have it.
I can think of one runway to which I have operated frequently, Aberdeen 34, which is short (1730m, I think) and which has a marked down-slope in the TDZ. If you approach there with excess speed and mishandle the flare leading to a deep touchdown, you will overrun the end. You must recognise the situation early and carry out a go-around. That is why I would, in stong gusty winds, approach in selected speed.
Flying is about risk management and one must at all times balance one risk against another. Company SOPs can be too prescriptive. I used to fly for a company which banned manual thrust - except when the ATHR was not coping or was u/s (allowable) - very silly and very short-sighted. I now fly for a company which encourages crews to think for themselves and employ whatever techniques are contained in the FCOM. Much more sensible.
Should your company ever operate to Aberdeen, or to Inverness, or to Bristol or Jersey it is denying itself advantage in banning selected speed. All of these airports have very short runways which can be difficult. Bristol has a downslope in 09 direction and Jersey's runway is a mini mountain-range. If the flare were to be misjudged, your choice would be between a go-around and an overrun (not a good idea at Jersey 27 - it's a 300ft drop to the beach!). I elect to reduce the risk of either by selecting my speed and side-lining G/S mini. Indeed, my previous company (when the fleet had sensible managers)ordered approaches to Jersey at Vls, either by amending Vapp or by selecting the speed.
Safe flying,
WS
I don't think G/S mini would have prevented the WAW crew from going off the end of RW11. They approached fast (+20kts IAS) with a tailwind well beyond limits (18 kts at touchdown) to a wet runway in heavy rain. They did not select autobrake either. There you have it.
I can think of one runway to which I have operated frequently, Aberdeen 34, which is short (1730m, I think) and which has a marked down-slope in the TDZ. If you approach there with excess speed and mishandle the flare leading to a deep touchdown, you will overrun the end. You must recognise the situation early and carry out a go-around. That is why I would, in stong gusty winds, approach in selected speed.
Flying is about risk management and one must at all times balance one risk against another. Company SOPs can be too prescriptive. I used to fly for a company which banned manual thrust - except when the ATHR was not coping or was u/s (allowable) - very silly and very short-sighted. I now fly for a company which encourages crews to think for themselves and employ whatever techniques are contained in the FCOM. Much more sensible.
Should your company ever operate to Aberdeen, or to Inverness, or to Bristol or Jersey it is denying itself advantage in banning selected speed. All of these airports have very short runways which can be difficult. Bristol has a downslope in 09 direction and Jersey's runway is a mini mountain-range. If the flare were to be misjudged, your choice would be between a go-around and an overrun (not a good idea at Jersey 27 - it's a 300ft drop to the beach!). I elect to reduce the risk of either by selecting my speed and side-lining G/S mini. Indeed, my previous company (when the fleet had sensible managers)ordered approaches to Jersey at Vls, either by amending Vapp or by selecting the speed.
Safe flying,
WS
Last edited by Wingswinger; 28th Apr 2007 at 08:39.
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I don't think G/S mini would have prevented the WAW crew from going off the end of RW11
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Hi Wingswinger,
my point was not intended to be that GS mini would have prevented WAW, just wanted to say how it was done before GS mini (ah, let's ad some 20 knots to Vapp today).
Your point of ops into limiting RWYs is valid, the above posts (especially of whino) didn't carry that remark so it rather sound's to me like some pilots/operators fly windy approaches alsways (irrespective of RWY legnth) in selected speed.
Still I think from an overall point-of-view it would be better to fly GS mini even if the LDG RWY is limiting and pay special attention to touch down on speed near the 1.000 ft point. Normally in strong winds you will have at least a light headwind-component that increases your RWY-perfomance. If you miss yout touch-down-point, you go-around so nothing unsafe there.
By flying selected speed, you deterioate your performance in case of a low-level windshear-encounter. This may not be that much of a problem in an A319 at 55 tons, but let me tell you getting low on energy in an A321 at 75 tons is a whole different story (we fly A319-320-321, don't know about your company).
In the time when we were not allowed to modify the FMS-calculated Vapp in order to be 5 kts above the FAC-calculated Vls there where some very nasty landings in heavy 321s (especially hot and maybe high airfields like MAD, ESB etc), just because even flying Vapp did not give the aircraft enough energy for a 'normal' flare. Imagine now flying 10 knots below Vapp and then perform a Windshear-Recovery...
My manual clearly states, that in case of expected windshear
- use managed speed in approach phase
- use AP and A/THR if practicable
Regards, MAX
my point was not intended to be that GS mini would have prevented WAW, just wanted to say how it was done before GS mini (ah, let's ad some 20 knots to Vapp today).
Your point of ops into limiting RWYs is valid, the above posts (especially of whino) didn't carry that remark so it rather sound's to me like some pilots/operators fly windy approaches alsways (irrespective of RWY legnth) in selected speed.
Still I think from an overall point-of-view it would be better to fly GS mini even if the LDG RWY is limiting and pay special attention to touch down on speed near the 1.000 ft point. Normally in strong winds you will have at least a light headwind-component that increases your RWY-perfomance. If you miss yout touch-down-point, you go-around so nothing unsafe there.
By flying selected speed, you deterioate your performance in case of a low-level windshear-encounter. This may not be that much of a problem in an A319 at 55 tons, but let me tell you getting low on energy in an A321 at 75 tons is a whole different story (we fly A319-320-321, don't know about your company).
In the time when we were not allowed to modify the FMS-calculated Vapp in order to be 5 kts above the FAC-calculated Vls there where some very nasty landings in heavy 321s (especially hot and maybe high airfields like MAD, ESB etc), just because even flying Vapp did not give the aircraft enough energy for a 'normal' flare. Imagine now flying 10 knots below Vapp and then perform a Windshear-Recovery...
My manual clearly states, that in case of expected windshear
- use managed speed in approach phase
- use AP and A/THR if practicable
Regards, MAX