737-800 Manoeuvring Speed
 

Morning all,

After 2000+ hours on the beloved A321 I am extremely fortunate to continue on the 737-800. Throughout my line training I consistently met with same scenario with trainers and find myself scratching my head. When left high thanks to ATC or for other reasons I would instinctively, when in flaps 1 or 5, (or useless 10 ha ha) with an open speed window, plan to increase my speed above the flap manoeuvring speed and increase my drag & ROD (which we always did on the A321, flaps 2 & 180 kts selected = drop like a brick). It was always met with NO!! I find the FCTM pretty vague at best. Any definitive nuggets?
Thanks

B737 Manoeuvring Speed
 

Use flaps 10, 180 knots and speed brakes. It will give you a good rate of descent.

Personally, I use the following high-drag configurations to re-establish the profile:

1. Flaps 5, 220kts, speedbrake
2. Flaps 10, 180kts, speedbrake

Failing that, it's time for the gear - or perhaps a short think whether an orbit/delaying vectors might not be a much better idea. Nothing in FCTM preventing the use of speedbrakes and flaps above the minimum manuevering speed for each configuration.

My time on the 737 (3/4/500), and early time on 777, we were advised “not to use the flaps as Speedbrakes”. This meant only select and fly at speeds below the flap selection speed (FCTM: “selection of the flaps to the next flap position should be made when approaching, and before decelerating below, the maneuver speed for the existing flap position”), and NOT use the placard speed.

The “youngsters” these days have either never been taught that, or do not consider the FCTM as authoritative?

My understanding is that this is due to premature wearing of the tracks.

This makes sense, and reminds me of a story from my youth: my father worked in logistics and one of the fleet vehicles was the venerable Antar tank transporter, which could reputedly only manage 30mph! When introduced to one of the senior men, who could apparently “work magic” with any of the fleet, a certain arrogant youth said “...but can you make it go faster than 30mph?” I He was put in his place with the reply “of course, but how long do you want it to last?”.

Lesson learned: just because it can, doesn't mean it should...

Not saying this is necessarily the same as your question, but open to discussion.

Flap 10 at 180 kts is 30 Kts below the flap 10 limiting speed, and is hardly using them as speed brakes....

I'll second that.

I think "using flaps as speedbrake" more applies to extending flaps (and say, flying 220kts with flaps 5 and speedbrakes retracted), when you really should have been using the speedbrake first, and only then adding drag if speedbrakes aren't enough to get you back on profile/speed.

Nothing against it, just poor technique.
:}

It depends on the operator. Did you fly 2000hrs Airbus with one operator or known as "common practice" with many operators?

Some Boeing 737 background:

Boeing has a history with flap problems (but more related to the use of triple slotted flaps) and sensors, and the "old school philosophy" has been not to take any risk and fly flaps only with appropriate flap settings. Boeing does not want you to use flaps as brakes, you select flaps only when within max 10kts of the current flap maneuvering speed. 20 years ago I was sometimes put in "flightfreeze" in the simulator during the TR if I dared to ask for flaps 1 at 222kts when clean speed was 210kts. It was 215kts max. It was the instructors way of saying it was important to be very speedminded and the speed had to be correct within certain limits.

On the 737-300, flaps 1 placard speed is 230kts, so there is not a lot of margin to play with. On the 737-400, flaps placard speeds are higher for flaps 1 (250kts) but the margin reduces with flap setting and F25/30/40 have common flap placard speeds. So in the end the aircraft is flown using exactly the same techniques as the -300.

As a pilot who flies combination of Classic and NG today I find the NG a classic fuselage with a misdesigned wing, leading to unworkeable flaps/speed schedules. Ie, the aircraft needs flaps 5 on the glide, but the speed can be ridiculously low for that flap setting. And I will revert to "classic" speed schedules, flying flaps 5/180 or 170 on the glide. But I wouldn't go any higher with flaps out...

On the 777 we used to select flaps without reducing our speed and that worked fine for flaps 1 and 5, but or higher flap settings the comfort level is a bit dodgy. And some pilots coming from other operators previously didn't really like it.

Hope this helps.

I only have couple of thousand hours on the NG, so I'm not going to claim I know everything (or anything for that matter), but what's wrong with flying the manuevering speeds for any flap settings?

It doesn’t always work with what ATC wants. ATC speeds (180 till...) with appropriate flaps (many times flaps 1) is not enough drag on the glide. At least in our ops...