Adding a 'Couple-a-Knots'
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.. Lol. It drives me crazy, the call out is 5kts below VAPP not 2 or 3kts! I think people forgot what's the meaning of VLS... The way some guys panic, they must think VLS = Stall speed. xD.I have no idea! Green dot speed I beleive? What I know is that getting below VLS is looking for trouble.
Edit times 10: I see, what I said is not really correct in my previous post but you understand what I mean: Slower, more drag then more thrust required to maintain VAPP... Or should I go back to the book? xD
I was referring to this graph page 5. From what I understand, a speed below VAPP and you are on the backside of the power curve.
https://www.slideshare.net/syedviqua...3-presentation
Last edited by pineteam; 26th May 2018 at 17:29. Reason: Link added and typo. Sorry it's 1h30am xD.
Only half a speed-brake
Exactly the point. Vls=Vref=Vapp.
+ 1/3 of the reported head wind for the reduction in of its speed in the boundnary layer below the anemometer height
or + 5 kts if A/THR used (to allow for its speed drops not expected to exceed -5 kts)
So, if the displayed Vfms is Vls+3, without really knowing which is correct, why add 2 kts? Worst case it is still Vref+3.
@CheckAMN: all good until you start to develop a "long landing standard" technique. Then one day going into a short-ish place people opt for a "short landing technique" (which should have not need to exist in the first place!!!). And it scary to watch them fail their first attempt at executing what they did not practice before, and actually, they have no idea or guidance what it should be like.
But as long as the shortest LDA is 2500 m, the discussion is admittedly academic. Unless one's ready to see the broader views presented by safetypee above. Similar to going for 3 red's on the PAPIs, boss.
+ 1/3 of the reported head wind for the reduction in of its speed in the boundnary layer below the anemometer height
or + 5 kts if A/THR used (to allow for its speed drops not expected to exceed -5 kts)
So, if the displayed Vfms is Vls+3, without really knowing which is correct, why add 2 kts? Worst case it is still Vref+3.
@CheckAMN: all good until you start to develop a "long landing standard" technique. Then one day going into a short-ish place people opt for a "short landing technique" (which should have not need to exist in the first place!!!). And it scary to watch them fail their first attempt at executing what they did not practice before, and actually, they have no idea or guidance what it should be like.
But as long as the shortest LDA is 2500 m, the discussion is admittedly academic. Unless one's ready to see the broader views presented by safetypee above. Similar to going for 3 red's on the PAPIs, boss.
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Ok thank you FlightDetent. But I don't know if you flew on the very old A321-100 and some -200 models with the wingtip fences: The flare is quite challenging and scary when the speed is only 1 or 2kt above VLS. Maybe it was a problem with the flight control computers but they were famous for hard landings. xD The one with Sharklets on the other hand, increasing the VAPP is looking for a very long flare. They are good gliders.
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Exactly the point. Vls=Vref=Vapp.
+ 1/3 of the reported head wind for the reduction in of its speed in the boundnary layer below the anemometer height
or + 5 kts if A/THR used (to allow for its speed drops not expected to exceed -5 kts)
So, if the displayed Vfms is Vls+3, without really knowing which is correct, why add 2 kts? Worst case it is still Vref+3.
@CheckAMN: all good until you start to develop a "long landing standard" technique. Then one day going into a short-ish place people opt for a "short landing technique" (which should have not need to exist in the first place!!!). And it scary to watch them fail their first attempt at executing what they did not practice before, and actually, they have no idea or guidance what it should be like.
But as long as the shortest LDA is 2500 m, the discussion is admittedly academic. Unless one's ready to see the broader views presented by safetypee above. Similar to going for 3 red's on the PAPIs, boss.
+ 1/3 of the reported head wind for the reduction in of its speed in the boundnary layer below the anemometer height
or + 5 kts if A/THR used (to allow for its speed drops not expected to exceed -5 kts)
So, if the displayed Vfms is Vls+3, without really knowing which is correct, why add 2 kts? Worst case it is still Vref+3.
@CheckAMN: all good until you start to develop a "long landing standard" technique. Then one day going into a short-ish place people opt for a "short landing technique" (which should have not need to exist in the first place!!!). And it scary to watch them fail their first attempt at executing what they did not practice before, and actually, they have no idea or guidance what it should be like.
But as long as the shortest LDA is 2500 m, the discussion is admittedly academic. Unless one's ready to see the broader views presented by safetypee above. Similar to going for 3 red's on the PAPIs, boss.
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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.
read my post again. Correcting VAPP for a incorrectly calculated FMS VLS is something I don't disagree with. The issue is with guys adding 2kts ONLY above VLS+5 for gust wind
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Its in interesting question that divides opinion at my firm. As far as I am concerned, the landing speed is Vls. We need 5 kts for the Athr in managed speed because its very tolerant to small variations from the target. So generally, I'm not concerned about at target speed close to Vls - the Athr is going to respond if we get below that hockey stick. I do however understand those who have got into the practice of landing at FAC Vls +5 - to each his or her own. But please please please, check the speeds as part of your descent prep, brief what you want to see on the PFD, especially if you expect your colleague to land at a particular speed, and check them during the initial approach. Check S speed from PFD and MCDU - that will tell you any discrepancy away from the ground. 800ft and IMC is not the time to be heads down fiddling with speeds in the mcdu, especially if one is PF at the time, and particularly if your colleague has no idea what your doing, and has no desire for your amendments...
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Scary thing is that as airlines transition entirely over to EFBs for landing performance there will come an entire generation of pilots that will not be made to do approach speed calculations using paper and might well have no idea of why the VAPP is what is, or at least specifically how it is calculated and the nuances of it. I believe that there are absolutely no paper performance charts at all for the 350.
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Apologies. You're right. Adding 2kt in that case doesn't make much sense, unless you really think the system isn't keeping up with the gusts, in which case, they may just be trying to bias it to a slightly higher airspeed.
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I'm all in favor of people flying precisely. We're all professionals and sloppiness is simply not acceptable from anyone given the responsibility of people's lives in their hands. For that reason anyone correcting VAPP for incorrect FMS calculations is fine with me.
However, we all know that Airbus (I won't speak of Boeing as I haven't flown them) would like thrust variation to be as few and as gentle as possible due fuel savings. And I'm sure anyone that has flown the 320 family has experienced being in cruise and suddenly having the thrust jump forward because the aircraft has reached cruise attitude minus 50 ft after a shallow decent in an effort to increase speed without adjusting thrust but which inevitably did not yeild a sufficient increase in speed (called soft cruise or something that like).
However, is anyone aware of just how the auto thrust behaves during an approach. Does it try to be gentle down to VAPP -5 Kts and then kick in hard, or does it wait for VLS? Or is there no difference at all? As for those flying manual thrust (rare these days I know) if you add 2 or 3 kts to give yourself more margin to VLS what is that saying about your trust in yourself. In a calm wind your VAPP should be VLS. And most checks call for a tolerance of only VAPP -5kts. What does it say of our own confidence in our flying skills when people do not have full confidence on the line to meet the standards they are expected to meet.
However, we all know that Airbus (I won't speak of Boeing as I haven't flown them) would like thrust variation to be as few and as gentle as possible due fuel savings. And I'm sure anyone that has flown the 320 family has experienced being in cruise and suddenly having the thrust jump forward because the aircraft has reached cruise attitude minus 50 ft after a shallow decent in an effort to increase speed without adjusting thrust but which inevitably did not yeild a sufficient increase in speed (called soft cruise or something that like).
However, is anyone aware of just how the auto thrust behaves during an approach. Does it try to be gentle down to VAPP -5 Kts and then kick in hard, or does it wait for VLS? Or is there no difference at all? As for those flying manual thrust (rare these days I know) if you add 2 or 3 kts to give yourself more margin to VLS what is that saying about your trust in yourself. In a calm wind your VAPP should be VLS. And most checks call for a tolerance of only VAPP -5kts. What does it say of our own confidence in our flying skills when people do not have full confidence on the line to meet the standards they are expected to meet.
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Honestly who cares? If they ask you and you don’t want it just be polite and say “no thanks”
On the a320, In my experience on newly built aircraft, the autothrust responds very slowly at low / intermediate thrust settings and in managed speed will quite often hover at the speed target - 2 or 3 knots.
I have seen this on approach fully configured with the speed staying a bit below commanded Vapp. In this case I will ask for the Vapp to be increased by a few knots so the aircraft is flying at the speed it’s supposed to be at. I’d rather be a bit fast than a bit slow. Just big picture stuff. And no, unless the LDA is limiting I wouldn’t recalculate anything. (,”)
On the a320, In my experience on newly built aircraft, the autothrust responds very slowly at low / intermediate thrust settings and in managed speed will quite often hover at the speed target - 2 or 3 knots.
I have seen this on approach fully configured with the speed staying a bit below commanded Vapp. In this case I will ask for the Vapp to be increased by a few knots so the aircraft is flying at the speed it’s supposed to be at. I’d rather be a bit fast than a bit slow. Just big picture stuff. And no, unless the LDA is limiting I wouldn’t recalculate anything. (,”)
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https://ibb.co/fb4jY8
Flew this morning on A319. As you can see, VAPP config 3 initially is only 2.5kt above VLS and the pitch is around 6 degrees. It was fluctuating between 5 to 7 degrees.
Later on, the Fo requested 2kt extra and the pitch was about 5 degrees.
Only 2 kts extra made a small but noticeable difference on the pitch.
on A319, a tail strike will occur at a pitch of 13.5 degrees with landing gear compressed.
Last edited by pineteam; 27th May 2018 at 15:17. Reason: typo
I seem to recall that there used to be a note in the FCOMs that the AOA calculated speeds were only accurate to +/- 3 kts so a lot of this seems to be academic especially since one can fly safely at VLS with manual thrust!
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Devil's advocate. What if today's one of the days when it's -3?
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At the end of the day, in my opinion, it comes down to technique and personal preference. This is an academic discussion really. With the buffers built into line operations, 2-3 kts won't cause a stall or runway overrun.
ML, #32.
I appreciate a practical approach, assuming that your ‘who cares’ refers to the question and not the speed.
Taking a more philosophical, pedantic view for discussion, how would pilots know if the new landing performance will not be limiting, particularly if based on the current calculation ?
This issue reflects a much wider problem in modern operations, airmanship, professionalism. Lack of precision #31, experience #28, systems and aircraft knowledge, and the effect of external influences - FDR, SOPs, error, blame.
We might learn from Bertrand Russell “I would never die for my beliefs because I might be wrong”. Are pilot’s nowadays betting their careers on belief more than knowledge; 2 or 3kts of belief or personal preference.
We train in simulators - we cannot die, small deviations are accepted (the error is necessary in order to learn), but we rarely learn; instead we take to the air with the attitude that small deviations are OK, which of course can escalate to accepting situations without actually knowing the margin in operation between safety and ‘death’, loss of licence.
Are we lacking risk management skills because we don’t know, don’t’ care to find out, don’t plan ahead, or fail to ask a question; the response at #9 might be the better question for the owner of originating query #1 to ask of her/himself.
I appreciate a practical approach, assuming that your ‘who cares’ refers to the question and not the speed.
Taking a more philosophical, pedantic view for discussion, how would pilots know if the new landing performance will not be limiting, particularly if based on the current calculation ?
This issue reflects a much wider problem in modern operations, airmanship, professionalism. Lack of precision #31, experience #28, systems and aircraft knowledge, and the effect of external influences - FDR, SOPs, error, blame.
We might learn from Bertrand Russell “I would never die for my beliefs because I might be wrong”. Are pilot’s nowadays betting their careers on belief more than knowledge; 2 or 3kts of belief or personal preference.
We train in simulators - we cannot die, small deviations are accepted (the error is necessary in order to learn), but we rarely learn; instead we take to the air with the attitude that small deviations are OK, which of course can escalate to accepting situations without actually knowing the margin in operation between safety and ‘death’, loss of licence.
Are we lacking risk management skills because we don’t know, don’t’ care to find out, don’t plan ahead, or fail to ask a question; the response at #9 might be the better question for the owner of originating query #1 to ask of her/himself.
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The "who cares" was directed at being asked the question if they would like a few knots added and getting agitated for being asked the question. I'm all for flying as precisely as is practical. Splitting hairs over 2 or 3 knots fast is going overboard (in the context of adding to Vapp if your LDA isn't limiting) again in my opinion only.
I hardly think It speaks to any kind of unprofessionalism, or lack of knowledge either. I would consider it being assertive and doing your job properly by watching what's happening on your instruments and making adjustments as deemed appropriate.
There is a very good reason that buffers are applied to speeds in the AIP and to stabilized critera for landing.
I hardly think It speaks to any kind of unprofessionalism, or lack of knowledge either. I would consider it being assertive and doing your job properly by watching what's happening on your instruments and making adjustments as deemed appropriate.
There is a very good reason that buffers are applied to speeds in the AIP and to stabilized critera for landing.
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Vref -3 works out to be approx. 1.23 Vso in the pictures provided by Pineteam. 1.23 Vso is within normal operating range.
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Simply put it is far far far more forgiving with a ‘couple of knots’ extra.
Sure you can fly at VLS, but you give away a lot of handling margin for what, 60 meters less landing distance?