Adding a 'Couple-a-Knots'
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Adding a 'Couple-a-Knots'
Honestly, I'm sick of guys asking me if I want to add a couple of knots to my approach speed. Honestly what difference does a couple (i.e. two) knots make. If you're going to add anything add at least a minumum of 5.
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Haha! Yeah I remember some guys won't even ask me and just forced a new higher VAPP and telling me how much it's going to save the day... 
I also like to add a few knots ( 2 to 3 knots) on the old birds. Especially A319 in conf 3 to lower the nose when the pitch is ridiculously high or on the old A321 when the VAPP is too close to VLS. 1kt is roughly 1 tonne, and few knots seem to work fine for me. I never question the VAPP of my colleagues tho. Should be a personal choice; Not a mandatory thing.
I also like to add a few knots ( 2 to 3 knots) on the old birds. Especially A319 in conf 3 to lower the nose when the pitch is ridiculously high or on the old A321 when the VAPP is too close to VLS. 1kt is roughly 1 tonne, and few knots seem to work fine for me. I never question the VAPP of my colleagues tho. Should be a personal choice; Not a mandatory thing.
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Well it all depends.
In most A320's, the fms and flight control computers calculate the speeds independently. When there's a difference, we're invariably heavier than we think we are, and thus the FMS wants to fly at a slower speed than is appropriate. In that case, I'll add another 2 or 3 kts to maintain the proper ref+5.
In most A320's, the fms and flight control computers calculate the speeds independently. When there's a difference, we're invariably heavier than we think we are, and thus the FMS wants to fly at a slower speed than is appropriate. In that case, I'll add another 2 or 3 kts to maintain the proper ref+5.
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Yeah. Just as a reminder: On the old aircraft VLS displayed on PFD is based on the AOA sensor ( reality) versus VAPP calculated by the FMS based on the figures inserted from the load sheet ( not very accurate eg: Assuming 75kg for adult uh huh 
) If VAPP is less than 5kt from the VLS, it means the aircraft is heavier than we (FMS) think we are, like Check Airman mentioned. I also like to keep 5kt rom VLS. Give you a nice margin in case you flare too high.
) If VAPP is less than 5kt from the VLS, it means the aircraft is heavier than we (FMS) think we are, like Check Airman mentioned. I also like to keep 5kt rom VLS. Give you a nice margin in case you flare too high.
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In my day, flying 1st generation heavy jets I always flew VREF + 10kts, easing back to VREF "over the fence". The reason I always gave for this was, it is easier to loose the access speed should the need arise. Try recovering from a sudden 10 knot speed loss when flying VREF.. Also your landing weight maybe higher than you thought. Prevalent during cargo ops..
These days one would probably be reported for an "unstabilized approach" or some other misdemeanor, for the above.
These days one would probably be reported for an "unstabilized approach" or some other misdemeanor, for the above.
Only half a speed-brake
@ pinteam & Check Airmen: Do not worry, everyone has been through that stage.
Airmann: I am not the most experienced, but never has my landing been made any better or worse by fiddling with the numbers. The sentiment of your post is fully shared, sir.
Airmann: I am not the most experienced, but never has my landing been made any better or worse by fiddling with the numbers. The sentiment of your post is fully shared, sir.
The reply to the query “… if I want to add a couple of knots to my approach speed” could be:-
‘What’s the correction to the landing distance?’
A numerical answer is an opportunity to debrief the risks in approach and landing, distance margins, accuracy of declared runway state, etc.
Not providing an answer leads to a wider discussion on balancing risks, particularly the combination of speed and touchdown position, and thereafter stopping distance, wet runway, and overruns.
https://www.skybrary.aero/bookshelf/books/900.pdf table 6, page 11
‘What’s the correction to the landing distance?’
A numerical answer is an opportunity to debrief the risks in approach and landing, distance margins, accuracy of declared runway state, etc.
Not providing an answer leads to a wider discussion on balancing risks, particularly the combination of speed and touchdown position, and thereafter stopping distance, wet runway, and overruns.
https://www.skybrary.aero/bookshelf/books/900.pdf table 6, page 11
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The reply to the query “… if I want to add a couple of knots to my approach speed” could be:-
‘What’s the correction to the landing distance?’
Is the landing roll not effected more by ground speed at touchdown than approach speed in the air? Notice I said roll because of course distance includes a short air distance where the excess speed is being bled off.
‘What’s the correction to the landing distance?’
Is the landing roll not effected more by ground speed at touchdown than approach speed in the air? Notice I said roll because of course distance includes a short air distance where the excess speed is being bled off.
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It's not a written procedure to add a few knots. I suppose it'd fall somewhere between airmanship and technique. I don't think an FAA inspector in the jumpseat would fault a crew for increasing Vapp when it's sitting right above Vls.
I've heard of one person (thankfully not at my airline) who uses ref+10 all the way to 50ft even in calm wind, all in the name of smoother touchdowns. That's something else entirely.
I've heard of one person (thankfully not at my airline) who uses ref+10 all the way to 50ft even in calm wind, all in the name of smoother touchdowns. That's something else entirely.
All good poimts.
We were on approach once behind a heavy, dead calm (too calm?). In the blink of an eye we lost 10kts. It only needs to happen once, when you're not prepared......
We were on approach once behind a heavy, dead calm (too calm?). In the blink of an eye we lost 10kts. It only needs to happen once, when you're not prepared......
Normally added on the A319s because the VS calculated in the FMGC isn't the same as the VLS on the PDF, thus an increase in Vapp speed to make sure at least +5 VLS speed is flown. A320s are better at having a similar VLS on the PDF and calculated on the FMGC
Only half a speed-brake
The question is, WARNING - this will go in direction of safetypee's post - what makes us feel so confident that it is the VLS that shows correct value and FMS+LDS speed is the wrong one?
Bonus: What is the certified approach speed? Is it Vref = VLS?
- Does Airbus say the VLS could be wrong by 2-3 knots?
- How is it possible to have a difference of 3 tons (equivalent) on an aeroplane with only 30 seats filled but empty otherwise - is the true passenger weight really 176 kg each?
- What tpe of VLS to Vfms spread do you see when flying the A/C out of paint shop after IL check, with interior removed and freshly weighted?
Bonus: What is the certified approach speed? Is it Vref = VLS?
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As per QRH, we are allowed to increase up to 15kt above VLS. It’s really up to you.
Everytime I increase the VAPP, I insert it in the Flightsmart landing data to have an accurate landing distance. Unless I operate on short runways ( which we don’t; the shortest one is about 2500 meters), I rather approach slightly too fast than too slow and ending on the backside of the power curve. My worst landings were most of the time due to lack of energy.
Everytime I increase the VAPP, I insert it in the Flightsmart landing data to have an accurate landing distance. Unless I operate on short runways ( which we don’t; the shortest one is about 2500 meters), I rather approach slightly too fast than too slow and ending on the backside of the power curve. My worst landings were most of the time due to lack of energy.
Last edited by pineteam; 28th May 2018 at 09:23. Reason: Erroneous info corrected.
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Adding speed due to incorrect VAPP calculations in the FMS I understand. Adding a few knots in order to lower pitch attitude in config 3 also makes sense to me.
But primarily I see the addition of 2 knots (and it's almost exactly that amount) due to gusty conditions even in VREF is correctly calculated. Firstly an Airbus has GS mini function which takes care of ensuring that a margin is added when there is a headwind on approach higher than that expected on touch down, so that you don't get caught out with the wind drop. Secondly VLS is an Airbus systems speed. It is not a structural or aerodynamic speed. Going a bit under VLS is not the same as going below green dot at high altitudes. And even if you do, at lower levels all commercial Aircraft with all engines running have plenty of power to get themselves out of the back end of the curve, and so dropping a couple of knots into VLS has no real meaning except frightening some pilots.
All your really doing by adding two knots is to increase your margin vs stall speed. But will 2 knots save your life? Are pilots getting a bit too paranoid here?
But primarily I see the addition of 2 knots (and it's almost exactly that amount) due to gusty conditions even in VREF is correctly calculated. Firstly an Airbus has GS mini function which takes care of ensuring that a margin is added when there is a headwind on approach higher than that expected on touch down, so that you don't get caught out with the wind drop. Secondly VLS is an Airbus systems speed. It is not a structural or aerodynamic speed. Going a bit under VLS is not the same as going below green dot at high altitudes. And even if you do, at lower levels all commercial Aircraft with all engines running have plenty of power to get themselves out of the back end of the curve, and so dropping a couple of knots into VLS has no real meaning except frightening some pilots.
All your really doing by adding two knots is to increase your margin vs stall speed. But will 2 knots save your life? Are pilots getting a bit too paranoid here?
RAT, #10, Is the landing roll not effected more by ground speed at touchdown than approach speed in the air?
I do not believe that it is because of the multiple effects of the increased air distance.
The key point is the increase in air distance due to the change in approach speed compared with that assumed in original landing performance (at the same wind speed). The change in airspeed / ground speeds are relative, although V squared is important during rollout.
The increased airspeed effects both the flare time and distance, plus any float due to the higher speed than required for the weight. When compared with the expected performance, based on an idealised landing profile based on Vref, then the aircraft would be both faster and further down the runway at touchdown.
Conversely, to retain the same safety margin assumed in the calculated performance, then the aircraft has to shorten the flare time to achieve the same touchdown point, and lose more speed - a fatuous argument where the limit would require a no flare landing with instant speed reduction.
Therefore any unaccounted speed increase reduces the safety margin assumed in the baseline landing distance.
Note Appx 1, para h (2) on page 6, - re adding speed: AC 91-79A Change 1, ‘Mitigating the Risks of a Runway Overrun Upon Landing’ https://skybrary.aero/bookshelf/books/3606.pdf
And note para j (3), page 8, - re minimum acceptable safety margin.
I do not believe that it is because of the multiple effects of the increased air distance.
The key point is the increase in air distance due to the change in approach speed compared with that assumed in original landing performance (at the same wind speed). The change in airspeed / ground speeds are relative, although V squared is important during rollout.
The increased airspeed effects both the flare time and distance, plus any float due to the higher speed than required for the weight. When compared with the expected performance, based on an idealised landing profile based on Vref, then the aircraft would be both faster and further down the runway at touchdown.
Conversely, to retain the same safety margin assumed in the calculated performance, then the aircraft has to shorten the flare time to achieve the same touchdown point, and lose more speed - a fatuous argument where the limit would require a no flare landing with instant speed reduction.
Therefore any unaccounted speed increase reduces the safety margin assumed in the baseline landing distance.
Note Appx 1, para h (2) on page 6, - re adding speed: AC 91-79A Change 1, ‘Mitigating the Risks of a Runway Overrun Upon Landing’ https://skybrary.aero/bookshelf/books/3606.pdf
And note para j (3), page 8, - re minimum acceptable safety margin.
Only half a speed-brake
Pin, say again what is the speed for bottom point of the drag curve at 60 t landing weight?
Last edited by FlightDetent; 26th May 2018 at 17:31.
Check Airman, #11, I don't think an FAA inspector in the jumpseat would fault a crew…
…providing they consider / adjust the landing performance; or … unless the aircraft stops in the overrun.
(JT, add FAA inspectors to the lawyers who can be found in the long grass at the end of the runway
)
…providing they consider / adjust the landing performance; or … unless the aircraft stops in the overrun.
(JT, add FAA inspectors to the lawyers who can be found in the long grass at the end of the runway
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I don't think it's paranoid behaviour at all. When I see Vapp sitting just above Vls, the airplane is telling me that the assumed weights are wrong.
Will we die if the adjustment isn't made? Probably not, but unless we're going to a short runway, I don't see the harm in flying the speed the airplane thinks I should be flying, as opposed to the speed the load agent thinks is appropriate.
Standing by to be corrected if my understanding of the Vls/Vapp determination is incorrect.
Will we die if the adjustment isn't made? Probably not, but unless we're going to a short runway, I don't see the harm in flying the speed the airplane thinks I should be flying, as opposed to the speed the load agent thinks is appropriate.
Standing by to be corrected if my understanding of the Vls/Vapp determination is incorrect.