Hello everyone!

 

When I fly my approach into an airport, such as SFO, I see that the FMC really wants me to be going pretty dang slow, like 160 to 150KIAS. But I know in real life, ATC would like me to fly a lot faster. Approaching SFO, for instance, planes are expect to fly 180KIAS until DUMBA or BARTN and slow to final approach speed only at the outer marker (AXMUL, I believe). What's the best way to simluate this? If I turn A/T to speed mode, I lose the VNAV and I have to control my own descents. But if I keep it on VNAV, the plane wants to slow to a very slow speed. And I don't like changing all the points to have a speed of 180 but maybe that's the only answer?

 

Ideas?

Hi,

 

I think you would need to change the points in the FMC.

On the other hand: as you said, in real life - when it's somewhat busy- ATC will vector you and give speed and altitude restrictions and you can forget about VNAV/LNAV.

 

Bert Van Bulck

1. Go to legs page and enter 180/ at DUMBA/BARTN.

2. Use SPD INTERVENE button on MCP (right of speed selector knob).

Looks like in both cases you might have early flap extention to maintain correct speed and stay on path.

select 180, in speed selector, after dumba reduce to final with flaps and gear. thats how its done in the real life and it works in the sim. I've done 210 until 10 DME and haven't had a problem reducing to final before 1000feet. Its all about timing the flaps and gear extension. Also feel free to use speedbrakes throguh flaps 15 to slow you down. At this phase in flight using VNAV isn't common, Level Change would be much more. Or better yet if you're established, arm APR mode and hand fly her using the FD. I personally prefer to use level change, rather than VNAV for most climbing and and descending. It is especially efficient for descent because it utilizes idle thrust through the descent. I have met plenty of pilots who prefer level change to VNAV.

Use VNAV through the descent of the STAR, but once you get closer to the airport you will have to switch to using level change/hold and managing your own speed.

A good practice that a lot of virtual airlines teach is to be around 210 kts and at +/- 6,000ft AGL about 20nm from the airport.

From there you're either being vectored by ATC or vectoring yourself into a left/right downwind pattern for the arrival runway.

 

I usually keep 210 kts on the downwind with flaps 1 in the NGX, and when I'm turning base I slow to 180 kts and go to flaps 5.

Capture the LOC and GS and stay at 180 kts with gear down until the outer marker, roughly 6.5 miles from the airport and roughly 1,600 ft AGL.

At this point you set your approach speed for flaps 30 (or whatever you're using from the approach CDU page), and increase flaps as you pass through each flap's tick mark on the speed tape until you get to 30 (or your chosen flap setting).

 

By 600-800ft AGL you should be at your final approach speed with your final flap setting, fully configured to land.

Don't be afraid to use your speedbrake either if you need it, but don't forget to re-arm them.

Isn't it stated in the FCOM that you should not deploy speedbrakes when flaps are deployed ?? Or did I misunderstand that ?

Isn't it stated in the FCOM that you should not deploy speedbrakes when flaps are deployed ?? Or did I misunderstand that ?

 

FCTM 4.22. Use of speedbrakes with flaps 15 or more can cause vibrations.

If you follow trip7cap's advice above regarding the arrival and approach (recommended), then you shouldn't need any speedbrake whatsoever. I've never needed to deploy speedbrakes once my indicated speed was below 250, which usually means I'm below 10,000 feet ASL.

 

Sent from my iPad using Tapatalk HD

If you're in VNAV, use an appropriate flap setting and SPD INT. Otherwise, just use LVL CHG or V/S.

 

Don't touch the SPEED button. Pretend it's not there.

Speedbrake usage is not recommended with any flap extension, and it is generally forbidden with flaps greater than 5 deg. Speedbrakes + flaps can result in pretty severe wing pertubations and wild noise if you do.

 

If you need to slow down/descend with flaps greater than 5 deg, then you will generally be using your gear/further flap extension to accomplish that.

 

Typical profile is an optional flaps1deg/210knts on the "downwind", flaps 5deg/180knts for the intercept, glideslope alive or 9nm - gear down, flaps 15deg/160knts, then flaps25deg and 30deg and Vref as glideslope passes midscale.

 

If you need to be faster at the marker, say 170 or 180 knts, still advance the flaps on schedule, but keep the speed high with SPD intervene.

 

Many airlines limit use of SPD to the final segment only, as unlike VNav, it gives no stall protection.

 

If ATC is calling for 210 knts to the marker, just say unable.

 

* Orest

thanks all for then info !

This is good stuff. I've never used SPD INTV or Level Change. I guess I'll have to play with them, but wouldn't mind a quick overview.

This is good stuff. I've never used SPD INTV or Level Change. I guess I'll have to play with them, but wouldn't mind a quick overview.

 

Open your FCOM vol.1 at pages SP.11.16 and SP.4.1 for usage and vol.2 4.10.4, 4.10.7, 11.31.26 and 11.31.38 for description.You can also use acrobat search typing in lvl chg and spd intv and speed intervention.

 

LVL CHG will hold your speed using pitch and almost constant thrust setting (idle or climb power).

 

SPD INTV will be used with VNAV SPD (the same logic as LVL CHG, VNAV path is not taken into consideration), with flaps not up, geometric or vertical path you will have VNAV PATH (airplane will hold FMC calculated path with MCP speed selected).

Practice it.