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.