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B738 NG Gear down Flaps 15

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B738 NG Gear down Flaps 15

Old 17th Sep 2015, 05:31
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B738 NG Gear down Flaps 15

Hi

How many people select gear down flaps 15, without waiting for green landing light annunciator lights to appear or do people correctly pause before flap extension.

I ve always been guilty of no pause.

Just something I read in the FCOM.

Thanks

Pin
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Old 17th Sep 2015, 05:52
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Some do... Some don't !

I don't... Can't see a reason for waiting.

The "waiting thing" is most common among pilots with a 737-300 background !

If I remember correctly, selecting the flaps without having the landing gear down and locked (green lights) on this type would sound the "Landing Gear Configuration Aural Warning" (which was really annoying), but it could be easily muted (just as on the NG)

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Old 17th Sep 2015, 07:00
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How many people select gear down flaps 15, without waiting for green landing light annunciator lights to appear or do people correctly pause before flap extension.
Eh?

Nothing about pausing in any of my -NG manuals. (Although I will concede that the way Pilot Monitoring duties are written it "could" be read that way)

As B737SFP writes the classics (-300/400/500) were a different beast, and selecting Flap 15 before you had the gear down with three greens did set off the Config Warning horn which couldn't be silenced.
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Old 17th Sep 2015, 08:07
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Regardless of type, I was always taught to keep my hand on the gear handle until I got 3 green, just as a habit to prevent that loud scraping sound. I was also always taught to only actuate one item at a time, so that if something goes wrong you know which system to troubleshoot.
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Old 19th Sep 2015, 05:27
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word is yes, it should be gear down, confirm three greens, flaps 15
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Old 19th Sep 2015, 07:13
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word is yes, it should be gear down, confirm three greens, flaps 15

Easy to say, but please explain the rational. Is it that it was your company's SOP? On Classics it was necessary because of the system design, on NG the necessity was removed. It must have been thought about by the designers.
You might consider it a good idea IYHO, but there must be a reason behind it.
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Old 19th Sep 2015, 08:03
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Gear Down 3 Greens then Flap 15

I can think of a couple of reasons for waiting until the Gear is indicating Down 3 Greens before selecting flap. Primarily, it makes sense to confirm the action taken results in the desired outcome. In this case, Gear selected Down - Confirmed Down 3 Greens. Select desired flap setting. In this case, Flap 15 selected - Flap 15 indicated. As previously posted, it makes sense to make the selection of Flaps 15 after the Gear is down 3 Greens, in the event a hydraulic malfunction occurs, to make it easier to identify which system is at fault. From a systems stand point it is also prudent to not overload the hydraulic system/s with both Gear and Flap running at the same time if they are both powered by the same system. Besides, what is the rush? Surely the aircraft is configured in ample time to preclude undue haste!!
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Old 19th Sep 2015, 09:08
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Proper configuration

Hello to all , please remember the proper position of the LE Slats with the trailing edge flaps position , so with the classics and the standard NG the answer is YES you should wait for three greens because it is an improper configuration to move your LE Slats to landing configuration ( full extended ) before you have the three greens that means down and locked , and the reason is that with the classics and the standard NG your LE Slats move to Full extended position with trailing edge flaps passing 10 , that is why if your airline is using flight data monitering or FOQA it will trigger an alarm of improper landing configuration with the classics and the standard NG .NOW it is different with the SFP because your LE Slats stay at extended position till 25 , then passing 25 they move to Full extended position for the proper landing configuration , so the answer is NO you needn't wait for three greens to set flaps to 15 with the 737 SFP ( although with mixed fleet the airline FDM or FOQA will still trigger an alarm but technically and aerodynamically you are OK and highly justified for your action ) .

Best Regards .
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Old 19th Sep 2015, 10:27
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That actually depends on FOQA configuration if they use the LE devices as trigger or not. Apparently ours did not, flying a mix of SFP and old NGs.
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Old 19th Sep 2015, 10:28
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MZ73 - I only flew classics so I can't comment on any variant of the NG - The LE slats extend to full passing flap 5. Flap 10 is a valid configuration for flight with gear up.

In all my time flying 737-2/3/4/5 we always had FDM - I always called gear dn/flap 15 at the same time (But only from Flap 5 - this was as per SOP - we did however pause between selections) and never had an issue with our flight data monitoring folk.

Personally, I feel you fly the aircraft to the SOP's. If the FDM folk get alerts from pilots flying SOP's, then the FDM program needs reprogramming, not the SOP's changing.
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Old 19th Sep 2015, 10:53
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Cough , Denti ; the FDM or FOQA alarm is usually a CAT 1 event which is usually monitored for trend and needn't a report or other action , and of course could be tailored and modified regularly according to airlines operational procedures and SOP's , I agree fully .

And I don't argue flying airline SOP's and following operational directives .
I am explaining technically and aerodynamically the aircraft proper landing configuration with both the standard and the SFP NG's ( Never flew classics )
Defined by the position of the LE Slats position in relation to the trailing edge flaps position with the different NG variants , which may clarify the requirement for some variants to select flaps 15 after having three greens and having this as an Airline SOP to stay within the proper Aircraft landing configuration
Which was the question at the beginning of the thread .
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Old 19th Sep 2015, 13:23
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One of the larger global NG fleets, renowned for its strict SOPs, does both together.

On the NG SYS A powers the gear, and SYS B the flaps/slats. You are not asking "more" of the hydraulics by doing both at the same time.

There are plenty of daft hangovers in SOPs that come from "that's the way we did it on the 200" for sample...
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Old 19th Sep 2015, 13:28
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hi me again.

Looking at two FCOMs from two different reputable outfits, its says in both that wait for three greens. Unless your FCOM is different, and please do check and highlight to us, we simply do what the controlling document tells us to do.
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Old 19th Sep 2015, 14:14
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Regardless of type, I was always taught to keep my hand on the gear handle until I got 3 green
What you were taught (and by whom?) and what is SOP, are often two entirely different things. So many items "taught" are personal opinion and not by the manufacturer.
My favourite beef are pilots (captains as well as copilots) who reach over and hold their hand on the gear lever at VR, waiting in breathless anticipation for the PF to ask for gear up. When queried, one co-pilot told me he had been "taught" that during his type rating in case there was an engine failure and the crew forgot to call for gear up.
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Old 19th Sep 2015, 14:29
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How many people select gear down flaps 15, without waiting for green landing light annunciator lights to appear or do people correctly pause before flap extension.

I ve always been guilty of no pause.

I first flew a 737 in 1977 and trained by a Boeing instructor pilot from Seattle. The technique then was "Gear down, flap 15, landing checklist to flaps"
There was no waiting for three greens then and l can't see the problem now.


Of course one can always dream up a perceived logical reason for waiting for the three greens before selecting further flap. How about this one for example. if you wait for the three greens to appear and you are interrupted by busy radio calls, you may forget to put the flaps to 15 ? I just invented that one of course; but is it logical? Of course not.
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Old 20th Sep 2015, 01:22
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There seems to be an awful lot of 'Folk Lore' floating around in this thread.
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Old 20th Sep 2015, 03:08
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At the end of the day, irrespective of whether your taught by Mr Boeing, just do what your manual says.

That will protect you in a court case issue.

Simple.
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Old 20th Sep 2015, 04:30
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I think some of this may go back to when flaps and gear were both on the same hydraulic system. I know they were on the 707 and don't remember for sure but think they were on the 727. I know I was taught to not move gear and flaps at the same time.
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Old 20th Sep 2015, 17:46
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Talking

Just put the gear down and remember to select the flaps sometime after. Flying shouldn't be this complicated !

By the way, let's say that during an engine start attempt you didn't have N1 indication prior to selecting the Eng Start Lever to Idle, would you ask for the Aborted Eng. Start NNC?

I mean, this checklist focus in motoring the engine to clear residual fuel and set the engine for another attempt.

One thing else: has anyone here ever flew a 737 with Fuel Control Switches instead of the standard Eng. Start Levers? The company I fly for recently updated our normal checklists adding this item, but I've searched the FCOM and couldn't find anything related to this change.

All the best guys.
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Old 21st Sep 2015, 11:37
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Whatever helps you sleep at night, Pin Head.

But I haven't heard of anyone being taken to court for "Gear Down, Flaps 15".

My FCOM does not say "wait for 3 greens prior to selecting Flaps 15".
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