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tecboy99

A/T During Flare

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Question, It seems like if I leave the A/T on for landing, The throttles retard at around 15 feet. Causing a floating effect. I thought the real aircraft brings the throttles to idle at 25-ish feet. Is this a bug, or am I doing something wrong?

 

 

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Have you set the correct approach speed in the FMC and is this speed selected and active on the MCP?
 

Looks a bit like you're landing too fast. FMC speed from the LEGS page active (170 kts), maybe?

Edited by olli4740

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It's more likely that your flare is too steep. Common mistake.

 

Its always 4-5 deg. Maybe I should be a little more gentle? 

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I've been flying VREF + 5. Generally around 140 ish knots.

 

 

For a test, see what happens during an autoland in clear weather: Do your throttles retard the moment you expect them to do?

 

If yes, I concur with James. Likely something related to your landing technique. Like not being fully stabilized or starting to chase the G/S just before crossing the threshold.

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I thought the real aircraft brings the throttles to idle at 25-ish feet. Is this a bug, or am I doing something wrong?

 

The manual states that A/T will begin the flare between 25-50' radio altitude.  Closing the throttles is a relatively slow process, though.  Cutting the throttle too quickly could result in a hard landing.

 

Edit:

I'm with the rest of the guys here, though.  My bet is that it's probably technique.

Edited by scandinavian13

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For a test, see what happens during an autoland in clear weather: Do your throttles retard the moment you expect them to do?

 

If yes, I concur with James. Likely something related to your landing technique. Like not being fully stabilized or starting to chase the G/S just before crossing the threshold.

 

I do tend to chase the G/S. Maybe I'll turn off the F/D so I'm not so tempted ^_^ . I'll do some patterns tonight and let you guys know what I find out. Thanks!

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I do tend to chase the G/S. Maybe I'll turn off the F/D so I'm not so tempted ^_^ . I'll do some patterns tonight and let you guys know what I find out. Thanks!

 

Don't turn off the flight director, you'll want it on should you need to activate G/A. Just ignore it once you're closing in on the threshold as the ILS "cone" becomes too small to actually follow at this point. Your loc and G/S readings will be way too sensitive below around 100ft AGL (roughly).

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Don't turn off the flight director, you'll want it on should you need to activate G/A. Just ignore it once you're closing in on the threshold as the ILS "cone" becomes too small to actually follow at this point. Your loc and G/S readings will be way too sensitive below around 100ft AGL (roughly).

 

Will do!

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I override and cut the throttles at 20ft (F1 shortcut) - done a lot in the real world too. They do retard to idle pretty slow at times coming from a high approach N1. 

 

Remember that the 77L lands a bit faster than it should when you're around 215t and below with Flap 30 due to the 137 knot restriction on the GE90-110/5B engine. I use Flap 25 a lot now which averages 145 knots with wind correction and flies a bit better. When Flap 25 is 140 knots and below- I wouldn't bother using Flap 30 if the LDA is acceptable and not an autoland. 

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A bit off topic with the 137kt restriction. I notice that when landing at higher elevation airports (usually the ones above 4000ft msl) the vref for flaps 30 does indeed go below 137, I've seen it go to 135. just wondering why?

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There are two switches just aft of the power levers, if you flick both of these to OFF it does wonders for your return to earth. Start the APU before hand however.

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A bit off topic with the 137kt restriction. I notice that when landing at higher elevation airports (usually the ones above 4000ft msl) the vref for flaps 30 does indeed go below 137, I've seen it go to 135. just wondering why?

Your TAS will be higher even though your IAS reads 135kts. Since the 137kt Vref floor is based on Vmca (I assume at ISA) the FMC probably factors for the conditions at a high altitude airport.

 

Regards

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Question, It seems like if I leave the A/T on for landing, The throttles retard at around 15 feet. Causing a floating effect. I thought the real aircraft brings the throttles to idle at 25-ish feet. Is this a bug, or am I doing something wrong?

 

 

PMDG did say they were adding the capability to override the throttles for the flare. Should make it nice and easy. 

 

However... I've just looked in the issue tracking thread and any mention of it seems to have now been removed.

 

Must admit I've found the same re the flare. Autothrust "begins" to power back at 15 feet. Don't think it's related to spool down time.

 

In any case, all will no doubt change in SP1.

Edited by martin-w

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Don't turn off the flight director, you'll want it on should you need to activate G/A. Just ignore it once you're closing in on the threshold as the ILS "cone" becomes too small to actually follow at this point. Your loc and G/S readings will be way too sensitive below around 100ft AGL (roughly).

 

Plenty of pilots deactivate the FDs when they're flying in nice weather.  Just fly the missed as published, you don't always need the electronics telling you what to do.

 

I've been in the Concorde for a couple weeks now... No FD guidance in that thing on departure, and it's quite the handful.  Great fun though.

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Plenty of pilots deactivate the FDs when they're flying in nice weather. Just fly the missed as published, you don't always need the electronics telling you what to do.

 

You mind providing a source for that?  Additionally, why would you fly the publised missed on a nice day?  Published missed is an instrument procedure.  If it's nice (so much so that you're going to kill the F/Ds for some random and unknown reason), you'd just go around and be resequenced.

 

 

 


I've been in the Concorde for a couple weeks now... No FD guidance in that thing on departure, and it's quite the handful. Great fun though.

 

You might want to do the tutorial a few times, then.  There's a pitch guidance bar, and then the F/D picks up very soon after departure.  Sure, it's not as "involved" of an F/D as some of the newer stuff, but to say "no guidance" couldn't be further from the truth.

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If you did switch of the FD's (it's called a Raw data approach) they will automatically pop up once you commence a go-around.

 

I do know raw data approaches are done a lot in training. Can't see why it would be done in normal line operations on the T7

 

With that in mind I do know guys that occasionally perform raw data take off's and landings on the bus if weather permits. Will ask how common (or if allowed) on the 777 fleet.

 

Edit - brains not switched on, FD off approaches must be allowed on the 777. Like the A3xx it will force the A/T to speed, good for NPA's. If we take Asiana for example, with FD off, the A/T wouldn't have gone to Hold and remained at idle.

 

I'm out at the moment, will check into it properly a little later.

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Okay, So I did a few CAT III ILS approaches. Then a several CAT II ILS approaches with A/T on all the way down. The throttles did idle out at the correct time. But, as martin-w said, the throttles do take several seconds to close up. After some practice, I can already tell my landings are getting much better. Right on the piano keys B). Thanks for all the help gentlemen! 

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You mind providing a source for that?  Additionally, why would you fly the publised missed on a nice day?  Published missed is an instrument procedure.  If it's nice (so much so that you're going to kill the F/Ds for some random and unknown reason), you'd just go around and be resequenced.

 

I am going to support Ryan on that, plenty folks turn the F/Ds off in good weather. Especially for visual approaches, FD can be distracting. Anyways unless SOPs tell you otherwise, it's up to the pilots preference. I've seen people leave the bars off for the whole flight, flying raw for proficiency sake, letting AP catch up only as NON-RNAV becomes unreliable.

 

About the go-around, there are some good reasons to fly published missed even on good weather day. Published missed approaches would make sure to separate you from arrival stream, and can act as noise abaitment procs as well. ATC can pick you up when clear of conflicting or noise sensitive area.

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Thanks for the explanation on the speed FLEX1978 (I apologize for not using your name I'm using my phone browser and it doesn't show signature)

 

Fabo (again apology for not using your real name) I also can see why turning the FDs off especially when on a npa approach and transition to a visual approach can cause problems, as FLEX1978 said.

 

Also flying an instrument missed approach procedure especially when you were on an npa/PA can assure terrain clearance, take NZQN for example.

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Received the reply below from a 777 Captain. Question was regarding use of FD on approach & confirming A/T reverts to speed... This is only one company's SOP! - not a blanket statement for all operators...

 

 

 

"You do it at your peril ! Not forbidden , but last thing u want to do after a long night. So leave it to the automatics till u get the "1000 stable " call . Stay out of trouble that way. These days we do more raw data stuff in sim , which is good. Normally take a/t out as well , but if left in stays in spd mode"

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In real world,the only time I've flown with the FD off is during VFR pattern work or in the SIM.  Even during visual approaches, if available, I keep the ILS or RNAV loaded and tuned up. Even when flying visual, i like to stay as close to the normal glide path as possible so i use the FD and ILS/RNAV as a reference(habit from flying heavies). Even on non precision approaches, we keep the FD on and load the approach in the FMS. Once again, this helps keep you close to the normal glide path. Once visual, you're not spending much time on instruments anyway so its easy to ignore the FD if it's a concern. During VFR patterns, it can be annoying when the FD is commanding a turn as you fly the pattern. 

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