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jetsflier

Configuring During Descent

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Hi everyone, this question isn't a glitch per se but mostly me trying to get some tips for approach.

 

My problem:

 

On approach I want to deploy flaps - so I use the force speed or whatever that's called and deploy them. But then my speed doesn't decrease without me using the speedbrakes, which seems entirely unrealistic as most approaches don't require them at all, from my personal experiences at the minimum.

 

I was wondering how people set up when they deploy their flaps and also how they keep their speed relatively low enough. I want to try to avoid the use of speedbrakes on descent whenever possible!

 

Thanks everyone! One happy PMDG customer here!

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The aircraft is indeed a slippery one. Personally, once it levels off at 10000 to slow to 240, I use speed intervene (which you mentioned as "force speed") to drop to 220 instead. I make sure I intercept the ILS at flaps 15 between 160~180 kts, and stable at that speed. It requires a little planning in advance, and you definitely have to reduce your airspeed earlier, when comparing it to the NGX for example.

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The company descent speeds in the T7 are pretty low and I would stick to them.

 

Start your descent before the calculated TOD to have some leeway with the speed. Slow down the aircraft a good deal before starting the descent. If you're cleared late for the descent slow her down even more, close to flaps extension speed (F1/F5).

 

Do everything possible not to be high AND fast at the same time. Decrease speed before you lower your FL in order to able "to get dirty" (flaps, or even gear, if needed). Give yourself options for energy management, don't wait until it's too late.

 

And ... no, from my POV, speedbrakes ARE allowed with highly efficient airframe designs, no matter whether it's Boeing or Airbus.

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It's more comfortable for the passengers not to use speedbrakes, but if you need them, use them.

 

I found the FMS wants to descend a little late for my liking, especially from FL400. I initiate descent 120 nm from my destination at this altitude, and all works out great.

 

Take advantage of level flight and turns to decelerate. e.g. last night I descended out of FL400 to FL100 with a Mach 0.85/320 kts speed profile. 300 ft before levelling off at FL100 I selected 250 kts. Autothrust remained at idle, and she decelerated nicely.

 

I remained at 250 kts (at 8000 ft) for the vectors by ATC to the approach. He had me overfly the approach to the runway, which I did at 250 kts (GS of nearly 300 kts), then as I turned downwind I dialled back the speed to 180 kts, and took flap as she decelerated. GW was 410 k lbs. At flap 15 I had to use speedbrakes to get her to descend to 5000 ft (she was only making 800 ft/min which was not fast enough), but speed management was actually easier than I thought it might be. Guess I'm used to the MD-11 requiring supertanker type distances to decelerate! :lol:

 

Best regards,

Robin.

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I have no problems with the descent. Since TOD to FL100, the speed almost never exceeds the vnav speed, and i only use speed intervention about 20/25nm from the airport where i'll land

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Jeremy,

 

After all the design work involved in calculating a TOD which enables an idle thrust descent (i.e. the most fuel efficient), I see no need to intervene at all SO LONG AS you have entered your descent winds forecast into the FMC and the actual winds are the same.

 

Any other way of descending is very likely to give the passengers a bumpy ride and burn unnecessary fuel as well.

 

HTH

Cheers, Richard

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Yes I learnt with this bird you have to reach desired speeds quite early, however when on approach fully configured Flaps full and gear down I find she slows pretty well, gears and flaps add the extra drag needed if you need to slow down quickly - I am in no way saying to be fully configured at like 23.000ft lol however use the speedbrakes as thats what they are there for.


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I see no need to intervene at all SO LONG AS you have entered your descent winds forecast into the FMC and the actual winds are the same.

 

You have to intervene, the 777 isn't the 737 and won't slow for you.

 

If you're high, maintain idle descent at the highest speed speed possible (you'll lose energy more quickly this way) and make use of the off path descent display to see to track your progress.

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On the 777, if you want to fly professionally, you NEVER deploy flaps in order to slow the aircraft down.

You wanna wait for your speed to decrease to around manouvering speed for your present flap setting, before you call for the next extended flap setting and slow down even further.

Energy management comes with experience, and using speedbrakes is no harm at all.

Actually, speedbrakes on 777 are used VERY frequently.

Let the FMC manage your descent with updated winds down to 10.000ft, then speed intervene and manage your profile in FLCH or VS in order to obtain a continuous descent to touch down (from 10.000ft and below, multipling your distance from theshold by 3 is a good technique to realize at what altitude you should be - ie. if you're at 30nm: 30x3=9000ft - at 20nm you should be at 6000ft - at 10nm be at 3000ft...)

Depending on your actual gross weight, slowing down the 777 can take longer than other airliners, so manage well in advance.

It could take you 6/7NM to slow down from 300 to 250kts in level flight without using speedbrakes, and 4/5NM from 250 to flaps up manouvering speed.

Try the following:

 

30NM @ 10000ft @ 250kts

@ 20NM bring the speed back to flaps up manouvering to reach by 16NM @ approx 4000ft AAL

Set Flaps 1 and slow down to F1 man spd to reach by 12NM @ approx 3000/3200ft AAL

Set Flaps 5 and slow down to F5 spd by 8NM @ approx 2000/2200ft AAL

When GS alive:

Gear down, Flaps 20, ARM speedbrakes and display landing checklist

At GS capture:

Flaps 30, set missed approach altitude on MCP

 

Control your speed with SPEEDBRAKES if it takes longer to decelerate to the various manouvering speeds.

Consider using Flaps 15 on GS if you intercept it too early, to better control airspeed (with F5 only on the glide, the 777 will accelerate)

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Oh, one more thing it could help you a lot managing yr descent is:

 

(example Dubai ILS30L)

Select the final approach fix or point for your approach (the point where you will intercept your GS, and do the following:

MODUS/2000 (which is the alt you wanna be over MODUS)

Put it in R3 on VNAV pag 3/3 (going by memory, but pretty sure)

 

Below this value, in R4, you have 3 indication: FPA - V/B - V/S that will give you the exact value of, let's say, Vertical speed (V/S) you have to maintain in order to reach MODUS at the desired altitude (in this case 2000ft)

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I've never had any problems with descent of the T7. The vnav works much better than the one on the NGX

 

During my descent the fmc will ocasionally flash that drag is required, and I'll hit the speed brakes, but once I get  to 10000, I disconnect the vnav and manage my own speed and descent to the GS.

 

Once I'm below 10000ft and doing about 240kts, I gradually dial the speed down and drop the flaps respectively until I intercept the GS. Once I'm on the GS I drop the final flaps which is usually 30 and speed is around 137kts. This has always worked for me

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I can let VNAV guide the plane from T/D to approach and the plane follows the path correctly. The 777 is much more slippery than the NGX on the approach, though, and I have found that with flaps 5 and unless I drop the gear, she will very gently begin to pick up speed if I'm performing a constant descending approach (vs. picking up the glide from below). Once on the glideslope, I need to use either a little speed brake, or either flaps 15 or 20 (FCTM says flaps 15 or 20 can be used with the gear up), until I drop the gear, or the plane won't slow down. But after doing that, the approach is a no brainer too, so it's just a matter of thinking ahead vs. reacting as the problems come.

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(...) Control your speed with SPEEDBRAKES if it takes longer to decelerate to the various manouvering speeds.

Consider using Flaps 15 on GS if you intercept it too early, to better control airspeed (with F5 only on the glide, the 777 will accelerate)

 

 

For the speedbrakes a rather obvious thing to do is to assign a hardware axis (lever) to your spoilers instead of using the default key command (#): That way your spoilers change from binary (either idle or fully extended) to analogue (gradual extension).

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