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View Full Version : B737 landing flap downwind to ensure stable approach


Judd
2nd May 2019, 14:00
Due to purported inability for company pilots to be stable by 1000 feet on visual circuit, (company requirement) one airline has introduced a requirement for landing flap in the 737-800 on late downwind and landing checklist completed before turning on to base leg on a normal circuit. This differs significantly from the Boeing FCTM for the B737-800 which displays a diagram called Visual Landing Pattern. This shows landing flap to be selected somewhere along Base Leg with a note that on final that the aircraft should be stabilised on final between 700-500 feet.

The equivalent of the FCTM called Pilot Training Manual published in 1982 for the Boeing 737-200 series depicts flaps 25 selected just after turning on to base leg following by landing flap as required turning final.
It has been many years since fuel savings methods were introduced into the 737 series at the time and that included using Flap 30 as the desired final setting for landing and that was done on mid final approach depending if IMC or VMC.

Fuel savings has obviously gone out of vogue since landing flap on the downwind leg introduced by this particular operator ensures higher fuel flow to maintain VREF 30/40 in level flight. At airports where bird strike risk is higher than normal, ingestion into an engine while the aircraft is in level flight at landing flap and speed, would necessitate quick footwork to maintain a safe flight path.

Are todays pilots so automation addicted (or simply lack hand flying skills) that they have difficulty in flying a normal downwind leg of a visual circuit and experience problems meeting stable approach criteria on final, that landing flap downwind and VREF +5 is now the new criteria to avoid risk of being pinged by the QAR?

AerocatS2A
2nd May 2019, 21:04
Sounds like overly restrictive stabilisation criteria are being used and this is interfering with the ability to fly a normal visual profile. I wonder how that company flies a circling approach? Probably forbidden.

Mullinax
2nd May 2019, 22:34
Are todays pilots so automation addicted (or simply lack hand flying skills) that they have difficulty in flying a normal downwind leg of a visual circuit?

Unfortunately, many are. And procedures always seemed to be designed for the lowest common denominator.

Callsign Kilo
2nd May 2019, 22:37
Are todays pilots so automation addicted (or simply lack hand flying skills) that they have difficulty in flying a normal downwind leg of a visual circuit and experience problems meeting stable approach criteria on final, that landing flap downwind and VREF +5 is now the new criteria to avoid risk of being pinged by the QAR?

In a word, yes.

gearlever
2nd May 2019, 22:43
Don't know the 737 but I assume the "old" procedure was more or less a constant power approach, now replaced by large power and pitch changes.

meleagertoo
2nd May 2019, 23:16
Vary from Mr Boing's procedures at your peril.
With 50 year's experience of knowing how to operate their own product the person that chooses to do different is demonstrrating a level of adventurism, arrogance and hubris that is unlikely to serve them well if anything goes wrong.
Have a care!

Capn Bloggs
3rd May 2019, 00:49
This shows landing flap to be selected somewhere along Base Leg
Who flies square base legs?

At airports where bird strike risk is higher than normal, ingestion into an engine while the aircraft is in level flight at landing flap and speed, would necessitate quick footwork to maintain a safe flight path.
So what's going to happen on a low level circle at say 400ft AAL?

Fully configuring on late Downwind on a normal circuit makes sense because that's what you do on a min wx circuit, at least that's what occurs in my "Boeing", as per Boeing's guidance.

scifi
3rd May 2019, 11:45
Maybe the fuel saving occurs because of a smaller circuit, instead of the cross-country 10+ Mile Final.

Capn Bloggs
4th May 2019, 13:58
Fully configuring on late Downwind on a normal circuit makes sense because that's what you do on a min wx circuit, at least that's what occurs in my "Boeing", as per Boeing's guidance.
And, I might add, says Boeing for a circling approach in some old 737 and 767 FCTMs I have recently acquired...

Smythe
4th May 2019, 17:22
Was just noticing that on the MAX 10, landing flaps have been modified to enable more flap 40 landings. As these ac are getting slippery, is flaps 40 becoming a necessity?

Dufo
4th May 2019, 18:09
In this case simply divert. Their books, their rules, their responsibility.

misd-agin
5th May 2019, 14:09
This shows landing flap to be selected somewhere along Base Leg with a note that on final that the aircraft should be stabilised on final between 700-500 feet.

Is that a current edition training manual? As far as I know a lot, or most, carriers in the U.S. require 1000' to be configured and perhaps fully stabilized on final.

Some of the best landing/handling flying done is the U.S. is landing to the south at DCA (KDCA) via the River Visual and the Expressway Visual to rwy 31 at LGA. Most pilots don't follow the depicted ground track in LGA. If flown as depicted I've heard FO's say "are we allowed to do this?!?" You roll out at approx. 300' after looking into CitiBank field on the turning descent that's approx. 'base' leg position.

DCA (KDCA) "cleared the visual to runway 01, circle to land runway 33, is also fun. 5100' runway. Mandatory go-around at 1700' (1/3 of landing distance). Weight restricted due to runway length so you're frequently right at the allowed performance limits. There's a blast fence at the end - FO after one landing "that wall was coming up fast."

misd-agin
5th May 2019, 14:10
Visual pattern or circling approach with low vis/ceilings? Two different circumstances.