A319 floating on touchdown

[tjf4375 7]

Hi there,

Hoping someone can help - I've been flying the Aerosoft A320 for some time, and have very much enjoyed it. However, I'm not having so much success with the A319 variant, and was looking for some advice.

Basically, I find it incredibly difficult to achieve a proper flare and touchdown with it - there seems to be an extremely small 'window' for the flare, and even when the throttles are retarded, the aircraft seems very prone to floating above the runway, resulting in a very late touchdown. I wondered whether this may be caused by retarding from autothrust mode - reason for thinking this is that the throttle levers are still in the climb thrust position at this point, whereas the actual thrust setting set by the FMGS during final approach is much lower. If flying an approach with AT engaged, when you get the retard callout, you'll be pulling the levers through higher thrust settings before it reaches the idle detent, possibly causing a floating behaviour?

I'm at a bit of a loss really - the A320 doesn't seem to have the same problem, which is equally confusing.

I'd be very grateful for any input,

Many thanks,

Tim

[Aviator1111 6]

Hi Tim!

I have also experienced what you are talking about, and the difference between the 320 and the 319 from this point of view. The problem is quite simple: first, the Vapp, what the FMGS suggests to use is a bit high. Not much, just about 1-2 kts higher than it should be, second, the idle thrust is also a bit high. It's okay that an A319 is able to start moving on the ground on idle thrust, but to reach more than 20 kts GS in half a minute...that is not okay. And this surplus of thrust is fair enough to make the aircraft behave during flare like we experienced.

But writing these kind of problems into this forum is completely pointless unfortunately, unless you are able to prove your point undeniably with a picture or a video, or something else.

So good luck to you!

Adam

[CaptOwen 3]

Start to slowly idle the throttles at the 30 feet callout and raise the nose a few degrees. The baby busses don't require a large flare.

[RobsonM 94]

For the A319 and A318 the tail strike angle is pretty high so you can do a way earlier retard and have lot's of room for additional flare. See this guy's video at 3:47. He pulls to idle just after 100 callout.

Also see rest of he's videos (most flying A318/19) to see other cool stuff you can do with A319 taking benefit of it's high tail strike angle clearance. Like this one at 2:51 keeping the nose wheel of the ground until just 80 or so knots. He explains details somewhere in the comments below the video.

Of course do not attempt to apply these techniques to A320 or A321 as you'll have to explain to the passengers why you've scratched the runway

[tjf4375 7]

That's interesting, thanks guys - I wondered whether an earlier idle might be the answer. I've discussed this with a few real world pilots, and they advised against retarding earlier though. I do agree that the VAPP does appear to be slightly too high, I've noticed that several times. Indeed it will take a real world pilot to point that out to AS if we want it changed, but in the meantime probably earlier idle will be the answer to try and shake off some of that extra speed. CaptOwen, you're absolutely right about the flare, I have noticed on many A319/20 videos that there is very little perceptible flare by the pilot on touchdown - as the aircraft is usually at about 3 degrees nose up anyway during the final approach, any more than that seems to result in floating.

[Airbus339 129]

There's also a big difference between the IAE and CFM model as the former has an idle thrust too high

[tjf4375 7]

I think I may have found the answer to this problem, or at least a major contributing factor.

I normally fly with A/T engaged until the 'retard' callout. What I've found is that the action of moving the throttle back from the climb thrust position to idle causes a momentary 'spike' in thrust, as you move through different throttle modes. This is a problem at 20 feet, because you end up 'ballooning' before the throttles reach idle.

The other day, I tried an approach with the A/T disengaged, and the landing was beautiful - this was obviously because I'd been adjusting the thrust levers in the lower half of the thrust range during the approach, and the position of the levers reflected the actual thrust setting at the 'retard' point, so there was no moving through higher thrust settings to get to idle. What I'd like to know is whether this is prototypical, or whether there is some feature that prevents this behaviour in the real aircraft that hasn't been replicated here. Presumably you'd need a function that disables any thrust adjustment between the climb and retard detents, if the A/T mode is engaged.

What I don't understand is why this doesn't seem to be a problem on the A320 - you'd expect exactly the same behaviour but I've not encountered the problem flying that model.

I'd be really keen to hear from Aerosoft about this, and also from any real world pilots - it doesn't seem right to me but not being an Airbus pilot, I'm not really qualified to make that judgement!

[Airbus339 129]

Ok, but in normal operations ATHR is always engaged on an Airbus ...

[tjf4375 7]

From FLEX/TOGA and during flight yes, but Airbus pilots frequently disengage A/T during the final approach. I had this discussion with two real world A319 pilots, who both said they will fly manual thrust approaches on the majority of occasions, unless they were at the end of a long sector or if the weather was challenging.

In any case, this doesn't answer the question about the issue I was describing with A/T mode.

[a320maxi 39]

Hi guys,

I've never had this issue, when retarding the throttles I don't get the spike you describe. Maybe it's a software or hardware issue. Or simply try retarding them a little faster, not giving the engines the time to spool up again.

My personal technique is to get the thrust levers out of the CL detent at 20 feet and let the engines run at some 30% N1 until I hear the "Retard" call out two times, which happens at around 10 feet, then I completely retard the throttles to idle. I start the flare at a little less than 20 feet, I slowly reach about 3,5° pitch up at 10 feet and then do a quicker flare to 5° shortly after descending through 5 feet. Most RW pilots would probably shake their heads if I wanted to use this technique in the real plane, but you would wonder how smooth and efficient on landing distance, as well as on touch down rate, this technique is, when mastered properly.

I had this discussion with two real world A319 pilots, who both said they will fly manual thrust approaches on the majority of occasions, unless they were at the end of a long sector or if the weather was challenging.

Well, depends on what you define as challenging weather, when there are strong winds with heavy gusts, pilots would normally disconnect the A/T, since it cannot react to wind changes as quickly and accurately as a pilot can.

[a320maxi 39]

Another useful tip would be not to do the "Boeing pull", which is pulling up quite violently low over the ground and then quickly pushing down a little to compensate for the resulting high lift. The "Boeing pull" allows you to shorten the distance you fly over the runway and it's fun to do on short runways with a 737, but definitely not a good idea in Airbuses... I always end up floating or simply going around.

[tjf4375 7]

Thanks for the comments. Yes, I'm used to flying the buses now so I've got out of the habit of over-flaring - the A319 in particular seems to be very sensitive to it! What I have noticed is that if properly configured, you'll already be at a good nose up attitude at 20 feet so I've actually found more success in very small, barely noticeable amounts of pitch up. Certainly in all the A320 cockpit dvds I've seen (and I've seen a few!), the flare is very subtle indeed.

In the video someone posted earlier, you can see the pilot retarding the throttles at 100 feet - I tried this on an approach this evening, and got quite a smooth touchdown, even with quite a severe crosswind, so I was quite pleased with that result. However, I did still get a slight float when the throttles were idled. I'm wondering whether there might be a bit of noise coming from my throttle controller that's causing this spike. I'm going to try it with a different throttle tomorrow, and see if I see any improvement!

[Airbus339 129]

I made four flights today with the IAE A319 and it's damn difficult to land!!

Will try your suggestions guys, thanks!

[tjf4375 7]

Can't speak for the IAE version as I've been flying CFM, but yes it is difficult to land, I'm just starting to get the knack of it now after dozens of botched long landings - earlier 'retarding' definitely seems to be the answer. Although slightly more flare is needed. I've just completed a successful flight from LGW-BFS; ATC decided to use runway 17 for landing today, despite the wind being much more favourable for 25. I had a 35knot crosswind so quite a lot of drift on final, but it was a stable approach. I retarded the throttles just after 100ft and there was no ballooning, and it settled down happily onto the runway. Touchdown was a little bit on the firm side, but felt like a good landing nonetheless!

[Joshua Che. 1601]

As a rule of thumb, retard throttle 10 feet higher than CFM and you will be fine.

The IAE takes a longer time to spool down, hence it results in a float.

[tjf4375 7]

That may be, but I've been using the CFM version and have the same floating issue. Retarding at 20 feet still results in ballooning. Moving the throttles from the CL detent to idle causes a thrust 'spike' that results in the floating issue. Is there any advice for this? As I've mentioned, I've got round the problem by retarding much earlier, but this is not necessarily realistic.

[Tom A320 4915]

As I've mentioned, I've got round the problem by retarding much earlier, but this is not necessarily realistic.

Why is it not realistic, if you see it in one of the videos posted earlier in this thread also done in RL?

[tjf4375 7]

Well by realistic, I meant standard practice - yes it is shown in the video above, but I have not seen this practice anywhere else, in any of the A320 cockpit videos I've seen. I have also spoken to two experienced A319 pilots who say that they would not advise retarding the throttles early as it could result in a stall situation if you encountered unexpected wind conditions before touchdown.

[HAL-9000 10]

The reason you are floating is likely because you're regarding the thrust levers too EARLY. The 319 is a lot lighter than the 320. Where in a 320 you would flare at 25 feet, in a 319 you should be flaring at 20 feet. Regardless of when you flare, you should be adjusting your pitch to make sure you don't land long, so if you find yourself floating you should lower the nose a bit to ensure you land within the touchdown zone. You dont stop flying the aircraft in the flare, closing your eyes and hoping for the best! You need to get that puppy down, put it down. Remember, the best way to avoid a float is to get your eyes to the far end of the runway when you cross the threshold at 50ft.

For avoidance of doubt, most Airbus pilots leave the autothrust in for most landings. If there is any spike in thrust, that is an error with the sim software and not an accurate reflection of the real thing. Thrust will still be handled by the autothrust until you select thrust Idle, although going below the current autothrust setting will impact it by limiting the autothrust. Thrust will NEVER increase when moving thrust levers out of the Climb detent with autothrust in, regardless of your phase of flight. What may be happening is that you're not factoring in the fact that thrust won't start decreasing until you move them so the thrust requested by them is less than that requested by the autothrust, so you might be expecting thrust to start decreasing as soon as the levers leave their regent, but that's not how it works. Close the thrust levers fairly rapidly (don't slam them closed, but don't take more than a couple of seconds to close them) and that should solve your issues.

And remember, eyes to the end of the runway! And if you're floating to beyond the touchdown zone, you should be going around! :-)

Edit: also for further avoidance of doubt, reducing thrust at 100ft, in any good airline, would trigger an immediate go-around followed up by an ASR. Don't do it.

[Galenki 1]

Well by realistic, I meant standard practice - yes it is shown in the video above, but I have not seen this practice anywhere else, in any of the A320 cockpit videos I've seen. I have also spoken to two experienced A319 pilots who say that they would not advise retarding the throttles early as it could result in a stall situation if you encountered unexpected wind conditions before touchdown.

https://youtu.be/BBTbTCLEp4M

Totally real, maybe you should stop talking to your so called real life 319 pilots and look it up for yourself. I always retard between fifty and twenty with 319/320 and never had a floating issue or else. You should barely have to flare if not at all if you're right where you should be on the glide slope (a little below), if you flare too much you gonna float depending on the wind or worse (also happens to real life pilots, can be seen all over youtube). I'm pretty sure not everybody flying the aerosoft bus really understand winds, baro pressures and all this things and just land "clueless" about what's going on outside the aircraft. Everything has to be taken into consideration and then you can start talking about something not feeling right in a simulator. Flaring on a well calibrated joystick with a low responsive curve like on a real bus should not take more than 30% of the course down, resulting in very little action on the elevator.

Also you can see in the link above how the pilot isn't flaring that much but is making mayonnaise with the stick to control the attitude of the plane till touchdown, can't really see a obvious flare action on the stick per se.

One thing that doesn't feel real to me is the spool up delay from an engine idling for more than 30sec, it's way longer on a real plane (@17:45 in the link above)

[The Dude 6537]

I think us real airbus pilots will call his stick behaviour a perfect example of what not to do. But it is always easier they say when sitting at home watching a video.

I concur fully with HAL-9000 on this floating matter. Although looking at the end of the runway for guidances is a bit flawed. But hey, explaining how to ride a bicycle in a book is also difficult and subjective.

[HAL-9000 10]

https://youtu.be/BBTbTCLEp4M

Totally real, maybe you should stop talking to your so called real life 319 pilots and look it up for yourself. I always retard between fifty and twenty with 319/320 and never had a floating issue or else. You should barely have to flare if not at all if you're right where you should be on the glide slope (a little below), if you flare too much you gonna float depending on the wind or worse (also happens to real life pilots, can be seen all over youtube). I'm pretty sure not everybody flying the aerosoft bus really understand winds, baro pressures and all this things and just land "clueless" about what's going on outside the aircraft. Everything has to be taken into consideration and then you can start talking about something not feeling right in a simulator. Flaring on a well calibrated joystick with a low responsive curve like on a real bus should not take more than 30% of the course down, resulting in very little action on the elevator.

Also you can see in the link above how the pilot isn't flaring that much but is making mayonnaise with the stick to control the attitude of the plane till touchdown, can't really see a obvious flare action on the stick per se.

One thing that doesn't feel real to me is the spool up delay from an engine idling for more than 30sec, it's way longer on a real plane (@17:45 in the link above)

If you flared at 50ft in my airline you'd be having to file an ASR for the go-around that would be happening pretty much immediately. That's way too high. As in the post above, 320 flare at 25 ft, 319 flare at 20ft.

Also, that isn't a video in which you should be judging a landing. I don't think the FO in that is particularly experienced. Look how much he is waggling the side stick, from the moment the AP comes off to touch down. He just keeps flailing it about like a feather duster. He retards the thrust too early and does a mini flare which led to a "5" ft call from the Radalt and a firm touchdown. If he hadn't produced a firm touchdown, he would have landed long. That's not how it should be done. I actually think he got lucky in that one.

Just because you see videos of some pilots flying in a certain way does not mean it's the correct way.

Also, for your information, I am a real A320 pilot with about 4 years of experience on the line.

I think us real airbus pilots will call his stick behaviour a perfect example of what not to do. But it is always easier they say when sitting at home watching a video.

I concur fully with HAL-9000 on this floating matter. Although looking at the end of the runway for guidances is a bit flawed. But hey, explaining how to ride a bicycle in a book is also difficult and subjective.

Dunno what to say. That's how I've been taught and I find that looking to the end of the runway greatly improved my landing technique. Honestly I thought it was standard practice. Certainly, when I do a firmer than usual landing, when I consider what caused it, it's generally because I didn't look to the far end of the runway. When I do, I usually get good, consistent landings. Do you not find it useful then?

[Emi 5161]

Dunno what to say. That's how I've been taught and I find that looking to the end of the runway greatly improved my landing technique. Honestly I thought it was standard practice. Certainly, when I do a firmer than usual landing, when I consider what caused it, it's generally because I didn't look to the far end of the runway. When I do, I usually get good, consistent landings. Do you not find it useful then?

I don't have experience on any Airbus aircraft, but just on the 172 and PA28, but I think what Frank wanted to say is that you shouldn't "focus" on the end of the runway.

Of course you do not look at the touchdownzone all the time, but rather towards the a further spot, but you shouldn't focus on anything.

When I land my Cessna I usually keep sweeping my eyes over the area next to the runway to the runway end, so that I get a view of everything. This is probably due to my experience flying gliders where you often have other objects or persons on the runway who push their gliders back to the takeoffpoint. But all in all even this explanation is a bit vague because it is very hard to tell what you actually do. You simply look where you think it is right to look, but try to keep the eyes at around the end of the runway.

[HAL-9000 10]

I don't have experience on any Airbus aircraft, but just on the 172 and PA28, but I think what Frank wanted to say is that you shouldn't "focus" on the end of the runway.

Of course you do not look at the touchdownzone all the time, but rather towards the a further spot, but you shouldn't focus on anything.

When I land my Cessna I usually keep sweeping my eyes over the area next to the runway to the runway end, so that I get a view of everything. This is probably due to my experience flying gliders where you often have other objects or persons on the runway who push their gliders back to the takeoffpoint. But all in all even this explanation is a bit vague because it is very hard to tell what you actually do. You simply look where you think it is right to look, but try to keep the eyes at around the end of the runway.

I see what you mean, You wouldn't go looking at different parts of the runway, and your attention in an Airbus wouldn't be on the sides of the runway or looking out for where people have parked their gliders. But you're right, in the flare the eyes are at the far end of the runway, but you're using that to judge the flare attitude and then using your peripheral vision to focus on the runway rising through the side windows to help judge whether there there any corrections necessary. You would also have a glance, if you think it's taking a long time, to make sure you're going to land within the touchdown zone so that you can initiate a go-around if it looks like you'll miss it.

[The Dude 6537]

As a bottom line you should ofcourse do what works best for you. I myself have made so many landings that it is automatic. I really have to think hard as to where I look at. I would not say I actively and consiously look at the end of the runway. With runway 23R in MAN or in BIO that would not work. Also with sharp CAT 1 or CAT 2 I do not even see the end of the runway.

I guess I look at everything that needs to be looked at (Touchdown zone, crossing aircraft, birds, debris on the runway, centerline etc) and ofcourse the peripheral vision works best if your head is kind of level with the horizon. The auto RA countdown also helps me to judge the rate of change as to when to start the flare. I have no fix RA where I start but it is surely not above 30 feet.

All this talking about landing techniques reminds me of an american viper instructor pilot who told his Egyptian student to keep the nose up during the flare. After another few bad approaches he told him to keep his nose up even more. The student replied that if he did that he would not see the runway anymore because he could not tilt his head any futher back.