737 Flap extension schedule

[CasperChen]

I saw a video about when to drop the flap and I've always had a bit of a problem with the timing of dropping the flap. Firstly, wouldn't the maximum extended flap speed be shown in the 737 as it is in the 320? (on the PFD). The video says that you can drop flap1 when the aircraft automatically slows down to Appr speed, and then drop flap5 when the speed reaches the PFD speed display to 1 or when flap1 has been completely dropped (green light shown). at the final intercept ILS or the last 5-7nm, drop landing gear and then drop flap15. the last is 30 or 40

I'm also curious about the PFD still showing a UP on landing, is the purpose of this for GA? I don't find it does anything practical in landing.








CasperChen

[Aeromar]

I saw a video about when to drop the flap and I've always had a bit of a problem with the timing of dropping the flap. Firstly, wouldn't the maximum extended flap speed be shown in the 737 as it is in the 320? (on the PFD). The video says that you can drop flap1 when the aircraft automatically slows down to Appr speed, and then drop flap5 when the speed reaches the PFD speed display to 1 or when flap1 has been completely dropped (green light shown). at the final intercept ILS or the last 5-7nm, drop landing gear and then drop flap15. the last is 30 or 40

I'm also curious about the PFD still showing a UP on landing, is the purpose of this for GA? I don't find it does anything practical in landing.




CasperChen

It is good practice not to use the flaps as brakes, unless you need to. Always shoot for deploying the first flap setting when close to or at the UP speed. That is, if VREF40 for your weight is 130kts, try to select F1 when you're flying 200kts. UP speed is always VREF40+70kts, even if you've chosen F30 for the approach. UP, F1 and F5 are separated by 20kts.

Then fly standard speeds on approach (180kts on intercept until 8nm and some 160kts until 6nm). In order to do this, make sure the speeds on every point on your legs page before the GS capture point match the speeds you want to fly. If you have set up your speeds in the legs page VNAV will sort out your vertical path to include deceleration segments. Fly it in VNAV until you get the hang of it to see how the AFDS does it and eventually you'll get to the point where you can do CDAs with more basic modes like LVL CHG and V/S to fine tune when on vectors.

A good point to select F1 is at about 11/12nm. You may need F2 to fly 180kts or you may choose to go F5 and bug 180kts. F5 between 9/10nm. Use F10 and or speebrakes if the airplane has a hard time maintaining speed when on the glideslope. Select Gear Down and F15 at 4nm in VMC or 5nm in IMC for a Low Drag Approach. Finish configuring after that and finish your landing checklist.

[mryan75]

It is good practice not to use the flaps as brakes, unless you need to. Always shoot for deploying the first flap setting when close to or at the UP speed. That is, if VREF40 for your weight is 130kts, try to select F1 when you're flying 200kts. UP speed is always VREF40+70kts, even if you've chosen F30 for the approach. UP, F1 and F5 are separated by 20kts.

Then fly standard speeds on approach (180kts on intercept until 8nm and some 160kts until 6nm). In order to do this, make sure the speeds on every point on your legs page before the GS capture point match the speeds you want to fly. If you have set up your speeds in the legs page VNAV will sort out your vertical path to include deceleration segments. Fly it in VNAV until you get the hang of it to see how the AFDS does it and eventually you'll get to the point where you can do CDAs with more basic modes like LVL CHG and V/S to fine tune when on vectors.

A good point to select F1 is at about 11/12nm. You may need F2 to fly 180kts or you may choose to go F5 and bug 180kts. F5 between 9/10nm. Use F10 and or speebrakes if the airplane has a hard time maintaining speed when on the glideslope. Select Gear Down and F15 at 4nm in VMC or 5nm in IMC for a Low Drag Approach. Finish configuring after that and finish your landing checklist.

Hey Omar,
Thank you very much for this, I was able to use your advice from this post to have my best approach yet in the 738:

https://www.youtube.com/watch?v=j-CN5em9Rwo

[Aeromar]

Hey Omar,
Thank you very much for this, I was able to use your advice from this post to have my best approach yet in the 738:

That was very nicely done. That looked like a continuous descent to approach on standard speeds like a professional would do it. No unnecessary mode changes, VNAV all the way because there was no need to revert to other modes, nice intercept with no overshoot. Very nicely done.

One thing you may want to know. Normally on descent, on the VNAV version that PMDG and many RL airplanes have, if you push SPD INTV it will take you out of VNAV PTH and it will switch to VNAV SPD, which is basically a legs protected version of LVL CHG. The exception to this is what's called ON PROFILE logic. When the airplane is ON PROFILE logic pushing SPD INTV will not switch from VNAV PTH to VNAV SPD. This will open up the speed window to allows you to select your speeds (200, 180, 160) as required by you or ATC, instead of having VNAV bug the flap manoeuvre speed which may be too slow for the sequence in large airports. We take advantage of this on non-precision approaches flown in VNAV and on precision approaches on the last stage of approach before GS capture (where the speed window will open anyway).

So you would come in right before F1 and as soon as you select FLAPS 1, while still on VNAV PTH, you can push SPD INTV and bug exactly the speed you want. The airplane will stay on path and it will not go to idle thrust unless it needs to to maintain speed and path. Then when you select further flaps you can bug your next speed manually either to the flap manoeuvre speed or to the round speed number you want (180kts to 8nm, 160kts to 6nm...).

Also the autobrake setting. Don't forget about it. It's a huge threat that can and does lead runway excursions consistently (which is a trendy key risk operating area in most places). Before descent when you calculate your landing performance you will consider Landing Distance Available, wind (brake on speed), temperature (brake cooling), runway condition (braking action) and airplane weight (resulting VREF) to make a decision on your landing flaps, reversers AND autobrake setting. All three settings are set and briefed as one.

[Iceman7]

You can also add rings on the fix page. By example RW07 /10 /5
It can also help you get started with the flap extensions approach.

[Solito]

Can you explain what is: ON PROFILE logic ?
Thanks

[Stearmandriver]

On profile logic refers to a submode of VNAV. Ordinarily, pressing speed intervention will open the speed window and the vertical mode will revert from VNAV Path to VNAV Speed. Once it's in profile logic though, it will remain in Vnav Path (meaning it will prioritize vertical path keeping over speed), but will allow you to use the MCP speed window to command a speed.

Regarding auto brakes, they're useful but I'd point out that they're optional. They're a fine thing to use in situations where they're helpful, but on a normal day it's fine to land without them as well, and that is encouraged as appropriate for proficiency and habit pattern maintenance. We don't want a generation of pilots who never brake manually any more than we want a generation of pilots who never hand fly approaches in IMC.