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Airmann
25th May 2018, 01:06
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.

Capn Bloggs
25th May 2018, 01:08
You tell 'em champ! :ok:

PS: what about "a few knots"?

pineteam
25th May 2018, 01:45
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.

Check Airman
25th May 2018, 05:58
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.

pineteam
25th May 2018, 06:13
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 :E) 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.:}

John_Reid
25th May 2018, 20:26
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.

FlightDetent
26th May 2018, 02:32
@ 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.

safetypee
26th May 2018, 10:54
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

RAT 5
26th May 2018, 11:05
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.

Check Airman
26th May 2018, 11:14
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.

Dan_Brown
26th May 2018, 12:38
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......

Danny42C
26th May 2018, 13:20
In my day, we used to say: "Add five knots for the Wife, and five for your Pension".

TheAirMission
26th May 2018, 13:30
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

FlightDetent
26th May 2018, 15:11
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?

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?
Clear as mud ...

Bonus: What is the certified approach speed? Is it Vref = VLS?

pineteam
26th May 2018, 15:51
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.

Airmann
26th May 2018, 16:39
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?

safetypee
26th May 2018, 16:59
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.

FlightDetent
26th May 2018, 17:03
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 leftside of the drag curve. Pin, say again what is the speed for bottom point of the drag curve at 60 t landing weight?

safetypee
26th May 2018, 17:04
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 ;) )

Check Airman
26th May 2018, 17:06
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.

pineteam
26th May 2018, 17:07
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?

I hear you. Many times it happened that my Fo will call '' Speed'' when I fly raw data and the speed dropped by like 2/3kts getting slightly close to VLS and they will call me '' Speed!':}.. 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.



Pin, say again what is the speed for bottom point of the drag curve for a 60 t landing weight?

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/syedviquarahmed/media-object-file-flt-ops-appr-seq03-presentation

FlightDetent
26th May 2018, 17:31
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.

pineteam
26th May 2018, 17:37
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. :}

Check Airman
26th May 2018, 17:59
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.

Well my point is that you do know which one is correct. The PFD Vls is correct. I'm not following your argument. We didn't have any short/long landing technique. As I stated before, if the runway length is limiting, I'm happy to let the Vapp sit on top of Vls. We're not going to die- mind the pitch though ;)

Airmann
26th May 2018, 19:00
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.
​​​​​​
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

Smokey Lomcevak
26th May 2018, 20:01
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...

Airmann
26th May 2018, 20:54
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.

Check Airman
26th May 2018, 21:16
​​​​​​
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

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.

misd-agin
27th May 2018, 00:53
How much does the pitch attitude drop if you go 2-3 kts faster on approach?

On a typical landing how much additional pitch is there before you have a tail strike?

Airmann
27th May 2018, 02:26
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.

MajorLemond
27th May 2018, 03:21
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. (,”)

pineteam
27th May 2018, 13:23
How much does the pitch attitude drop if you go 2-3 kts faster on approach?

On a typical landing how much additional pitch is there before you have a tail strike?




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.

Meikleour
27th May 2018, 13:53
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!

Check Airman
27th May 2018, 14:26
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!

Devil's advocate. What if today's one of the days when it's -3?

Check Airman
27th May 2018, 14:35
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.

safetypee
27th May 2018, 21:29
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.

MajorLemond
28th May 2018, 03:00
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.

misd-agin
28th May 2018, 03:08
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.

Vref -3 works out to be approx. 1.23 Vso in the pictures provided by Pineteam. 1.23 Vso is within normal operating range.

hoss
28th May 2018, 07:32
May I add a few words.

”measure it with a micrometer, cut it with an axe”.

Safe flying.

(context: Australian, 737)

PENKO
28th May 2018, 09:14
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!
Safety is not so much the issue. A few knots above Vapp has a huge effect on flare characteristics of this aircraft ánd on top of that provides you with margin to avoid planting it in when the wind drops out on you in the flare like it always does in for example AMS runway 06. Ground speed mini has long gone to bed at that stage.

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?

FlightDetent
28th May 2018, 11:00
Well my point is that you do know which one is correct. The PFD Vls is correct------
Devil's advocate. What if today's one of the days when it's -3? Now me playing Robin to devil's advocate: If on a given day, the displayed Vapp is Vls +5 AND at the same time the FAC is under-reading by 3 knots: should we not add +3 to cover the eventuality, making it VLS+8 at least at all times?:ooh:

Will you also acknowledge that Airbus went to certain lengths and already adopted a modification for PFD, where the VLS is displayed based on FMS&LDS data, so the habit of fiddling with Vapp is eradicated systematically? :E Are we really smarter here than the OEM engineers and standards technical pilots, as well as the financial controller who signed for the investment needed to develop the mod?


We didn't have any short/long landing technique. Post a picture / coordinates of your next (MLG) touchdown, dare? Or at least your most frequented landing runway.
As I stated before, if the runway length is limiting, I'm happy to let the Vapp sit on top of Vls. That awfully sounds lot like a different technique for a short LDA, pardon my french. :D

Here's the point: if you are willing to fly closer to displayed Vls on a limiting rwy (please do say what lenght is limiting for you - I mean what distance), why get all excited with Vls +4 on a long runway? Why not get a practice of flaring from Vls +3: at least we'd train a bit and stand lesser chances of screwing up when shooting into a limiting LDA with Vapp sitting atop VLS, hm?
There are some seriously good points in the thread.

measure with a micrometre, cut with an axe - what's the point (my language's own version: a precise calculation of inaccurate values)
if suspect of the weight, work the work and brief it with S-speed data, do not start playing smart only after landing flaps is gets extended.
the debate is academic for a day's flight, but at a grass-root systematic level quite relevant
the certified approach speed is Vref. The additions go on top for a reason.
sloppy flying and lazy thinking is not the target state for a professional

icemanalgeria
30th May 2018, 16:50
I agree with you john.
some examples are landing in HER where you have sea, cliff runway, Or MBA Trees, Valley Runway always give a sudden drop in energy at a time its not easy to recover with thrust.
I've briefed many a new copilot on possible speed loss, when we get it they ask how did you know we'd get speed loss I answer experience and now you gained that too.
An old boy told me, now i'm the old boy. I hope you young guys appreciate this knowledge as I do, and I bet as John does.

rickseeman
30th May 2018, 20:51
I guess this thread sums up all the excuses people use for approaching too fast. I once watched 1,000 airliners land at a major airport. Everyone one of them approached too fast and landed too long. Vref is already 30 percent above stall speed. How much do you need? Since I started flying 35 years ago very single person that has died trying to land at my home airport was trying to land way over Vref. And they all had an excuse. And these were all very experienced pilots. One of them may have been a former Air Force One pilot. These weren't dummies. But they were all (like everyone else) coming in way over Vref. And there will be at least 10 more crashes from coming in over Vref before you hear of a single crash from going too slow on final. Come in as fast as you want guys. It will be job security for the NTSB.

Cmon-PullUP
3rd Jun 2018, 12:31
On the A320, a 5 kts increase in Vapp, increase ldg distance roughly 8%
Throw in a little tailwind, late flare, drift, termals and late breaking as you wish.

I am not anal about a few extra knots with all of the above considered, but I am very sure a lot of those asking for a few extra knots, haven't got a clue what the effect is. On a 2500+ m rwy it is not a problem, but it might very well be on shorter rwy's.

pineteam
3rd Jun 2018, 16:45
Unless you operate in extremely short runways, Using the EFB, an A320 max landing weight at 64.5T in ISA condition and no wind will have a landing distance of only 2350M with auto brake medium with No Flaps and No Slats with a VAPP of 185kt and only 1750M with manual braking. You would have to land way past the TDZ in normal condition to overrun this aircraft.:}
Not saying that it can’t happen, but that’s not the biggest concern. In worst case I rather overrun the end of the runway at 20/30 kts than crashing short of the threshold.

Edit: I’m not adding « couple of knots »on some aircraft because I’m scared to stall but to have better control while flaring and to lower the pitch on old A319 with conf 3.

Centaurus
4th Jun 2018, 06:35
I've briefed many a new copilot on possible speed loss, when we get it they ask how did you know we'd get speed loss I answer experience and now you gained that too.

.Real story. 737-200 on dark night ILS to Runway 6L Guam Agana in the Marianna Islands. Cloud base about 1500 ft There are two runways at Guam. 6L and 6R. 6L has ILS. 6R has no aids. We received Instructions from ATC to break right when visual for sidestep right to 6R. As mentioned, there were no aids on 6R, so once you break right from the localiser 6L, it is a matter of glide path judgement. A taxiway with holding point joins 6L and 6R at their landing thresholds and separates both runways by about 300 metres. On this occasion, a PANAM 747 was holding on the taxiway intending to depart 6L (10,000 ft long). At 4 miles on final and breaking clear of cloud, we announced side-stepping right to land 6R. ATC then clears the 747 for take off 6L. So far, so good. With no glide slope guidance available for 6R, and glide slope 6L unusable for 6R, we drifted lightly high as we crossed threshold 6R. Wind calm.

Without any warning, turbulence hit the 737 which rapidly banked 20 degrees left and right and sank like stone. At the same time a stunned co-pilot called "Christ! Bug minus 20." . As PF I firewalled the thrust levers and hauled back for a raw data go-around on instruments. Fortunately this may prevented what would have been an extremely heavy and uncontrolled touch-down. We went into cloud while on the go-around and were then radar vectored for an ILS and landed safely. ATC queried the reason for the go-around and was told by the PM "severe windshear."

In fact, it was not windshear as such; but break-away jet blast from the 747 still on the taxiway at 90 degrees to us. Despite being cleared to take off on 6L some three minutes earlier, he had delayed lining up for some unknown reason. He did not tell ATC. From the left seat on short final I was aware of a shape with flashing lights on the dark taxiway adjoining both runways but didn't twig it could have been the 747. We had then passed close behind him as we crossed the threshold of 6R just as he opened up to break-away power to taxi for 6L. His jet blast hit us just before we flared. What saved us was the fact we were slightly high on slope over 6R threshold.
. All the briefings in the world cannot cover the one-in-thousand unexpected speed loss.

RAT 5
4th Jun 2018, 10:04
Similar learning experience as F/O PF, well anticipated by one of the older more wizened brigade of captain as was more common in those days. LGW, high traffic flow, the common "expect late landing clearance" i.e. around 200' and B747 lined up & cleared to go. Old wizened LHS warned to beware of turbulence and speed fluctuations as the beast ahead rolled. Don't over control on thrust nor flt controls. Firm and decisive. He was correct. Rock & roll <200'.
A message to pass on whenever I could.
Off thread, but there was also another message passed on, learnt from an interesting upset report, of medium a/c passing behind a heavy at crz FL. They had the mandatory separation, but hit the rough wake and went to significant bank angle. Not nice at night. After my first encounter of similar scenario, whenever I was vectored to pass behind a crossing a/c, I always asked what type, and if close behind a heavy nudged up 100'. It could also hit you if further away and 1000' below; a bit like being in trail on NAT tracks.
Sorry for the drift.

FlightDetent
5th Jun 2018, 11:37
I’m not adding « couple of knots »on some aircraft because I’m scared to stall but to have better control while flaring and to lower the pitch on old A319 with conf 3. My opinion is that it's psychosomatic, i.e. would only happen if the pilot believes so.

Your own picture:
https://s19.postimg.cc/9eo685wq7/A319_pitch.plus3kt_not-really.jpg (https://postimg.cc/image/9eo685wq7/) (click open in new tab to expand)

The pitch decrease is 0,74 degrees. Yet at the second shot, the A/C is accelerating and V/S is 800 fpm, not 700 anymore.
- I would agree the pitch changed by 0,6 degree, with all other things equal, due to the speed increase of 3 knots as photographed.

However, the Vapp increment was 2 knots. Pin - objectively - you are targeting a pitch change of 0,4 degree
: "to have better control while flaring and to lower the pitch on old A319". Come on.

Still, I do trust your word it is better. My claim? It's your mind playing tricks, not the aerodynamics/mechanics. You may feel more confident, trust the machine better, and be relaxed. That IS the mindset for a nicely controlled and well-organized landing. Some guys just do not need to add the 2 knots to get there. :ok:

You can be one too. Do a test, stop adding those tiny bits for 2 months and see: did the landings get worse?

Or be slick: propose to your F/Os: "Do you think those 2 knots really make a difference in handling a 50t jet in seafront breeze? Is it not just the yellow Vls mark scaring the hell out of us and putting us on the far side of the stress-performance curve? Would you like to try this one landing without adding a thing?" And watch them master it regardless.

my 5c.

Callsign Kilo
5th Jun 2018, 11:49
My answer is 'why?'

If the headwind component is 10 knots or less.
If a specified maximum increment is stipulated by the QRH

In manual flight, people don't generally fly their selected speed anyway (it's more than likely faster) and in most cases the only answer to why they want to fly a 'few knots faster' is to achieve a smoother touchdown. All a load of twaddle that has crept into the operation over numerous years by people who think they know better.

pineteam
5th Jun 2018, 12:21
FlightDetent I understand what you say. On the picture I was PM and the FO wanted those 2 knots extra. Myself I also do that but usually 2 to 4 kts extra or whatever is required to lower the nose when it's sitting at 7/8 degrees pitch on A319 config 3. I do not do it all the time as like you said, I like to try different techniques. On the old A 321, The aircraft seems to respond better with those little extra. I'm really not afraid to fly close to VLS as I know it's still safe. I see some guys who do not add anything and fly at VLS +1/+2 and they manage it but I also saw some very interesting landings. Were they related to that? Maybe not. But from my experience, it seems it works better with that extra speed with my landing technique at least; I'm the kind of the guy who has the tendency to flare too much that not enough. So those extra knots are my best friends when I screw up and flare too much and float xD. I will accept the challenge and not add any speed to the VAPP for the next 2 months and let you know.:}