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

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)

:ok:

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.

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.

word is yes, it should be gear down, confirm three greens, flaps 15

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.

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!!

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 .

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.

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.

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 .

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...

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.

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. :ugh:

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.

There seems to be an awful lot of 'Folk Lore' floating around in this thread.

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.

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.

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.

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".

That's why I raised the question my friend!

Who cares, just don't over speed them, and don't wait too long. "TOO LOW, GEAR. TOO LOW, FLAPS" is little too late.

I have to admit, flying at altitude in a part of the world that seems to like tailwind approaches....

I'm mostly using flap 10 to help keep the speed in check on at least on approach each day. The SFP can be a pain on those occasions......

Captain Freire
 

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None of the answers is fully correct.Imagine that you don't wait and you get one red landing gear light.What's your next action? Check-list to try to solve the gear problem.Where is your flaps:15. Which one offers more drag and consequently, more fuel consumption: Flaps 5 or flaps 15? Think about it and you'll see that Boeing is not stupid.There's a board of very experienced pilots preparing the procedures with caution and logic.Take care and follow what's written properly.

In the 737 NG procedure, the PF issues the combined command: “GEAR DOWN, FLAPS 15”, and the PM carries out the selections.

However, the key procedural intent remains unchanged:

The gear lever selection and flap 15 selection are still intentionally sequenced with a verification barrier in between, even if the callout is combined.

The PM:

• selects gear DOWN
• confirms three green landing gear indicators
• then selects flaps 15

Why Boeing structures it this way:

The landing gear lever position is only a command to extend, not confirmation of status. The system can still be:

• in transit
• asymmetrically extended
• or affected by a malfunction (gear disagree / unsafe indication)

So the three green lights are the required positive confirmation of “down and locked” status before the configuration progresses.

Flap 15 is part of the landing configuration build-up, and Boeing’s intent is to ensure the aircraft is in a verified stable configuration state before further increasing drag and changing energy management characteristics.

Bottom line:

Even though the PF issues a single combined call, the system logic and SOP intent still require:
gear status confirmation (three green) before completion of the landing configuration to flaps 15.

Can you ask the AI you got to reguritate this where that intentional sequencing is described in the FCOM/FCTM? I can't find it in my manuals.

To those people reading the FCOM:

When the wording of the FCOM is
*Set the landing gear lever to DN
*Verify that the green landing gear indicator lights are illumated
*Set the flap lever to 15
*Set the engine start switches to continuous"

It does not stop you from doing this in one sequence. The check of landing gear indicator lights does not prohibit you from moving on and setting the flap lever to 15. There is no reason to delay the start switches either.

In the FCOM you will notice that from the moment the engines are started, Boeing asks you to verify lights every time they are not covered by the master caution system. When you start the engines, at some point you will select the packs on. Boeing does not ask you to verify the pack light when you select it, because it will be covered by master caution. When you look at the selection of takeoff flaps, Boeing will ask you to "verify that the LE FLAPS EXT green light is illuminated" in the same way. I've known companies that will ask pilots to wait for the green light before they can do the flight control check which is not necessary. The system is protected. You can continue, however at some point you as a pilot have to do the check to confirm.

Same philosophy with the selection of landing gear, and speedbrake arm on approach. Boeing explicitely asks you to verify the appropriate light as they are not covered by master caution. There is absolutely no need to wait for 3 greens before you can select the next flap position and select continuous ignition.

It’s been a long time since I flew the 737 classic. Just checked an old FCOM and F15 only triggers the gear horn with the thrust levers below 30 degrees. It can be silenced with the cutout switch until you have greater than F15. So do 737 operators fly 160/4 with F15 and the gear up? Pretty sure we did to keep the noise and fuel burn down. Seem to remember pressing that button every time the thrust levers came back.

As someone said, the FCOM has to be written somehow - the order sometimes matters, sometimes it doesn’t. In this case it doesn’t in my opinion. So long as you arrive at your stable approach point stable with gear down and landing flap then who cares how you do it provided it’s sensible and not a rushed approach. 3 greens is hopefully checked a second time properly as part of the landing checklist (although it can be automatic response without looking at the indications under high workload)!!

We all strive for low workload approaches but if you do find yourself a bit hot at F5 then gear down flap 15 is a good place to start the recovery. Waiting to select F15 and slow down just wastes time and distance.

And “not overloading the hydraulic system”
Is nonsense.

I reread this a few times, and am still not seeing the problem.