Difficulty in slowing down

[JoeDiamond 67]

Remember, flaps are used to slow down the aircraft and speedbrakes are used to increase drag. We do not use flaps as drag devices, therefore use “Flaps to Slow Down and Speedbrakes to Go Down!”

We? You're a pro now?

[hs118 706]

We? You're a pro now?

 

Yeah I'm not understanding that logic either. I fly US Navy aircraft in sim and speedbrakes are used for slowing down. Flaps are for increasing lift at slower speeds.

[Driver170 42]

From a line training manual! Never mean't me

[RW1 615]

 

 

This is not true to real operation of a 737.

If you would like the opinion of a Real World 738 pilot with thousands of hours in command who fly`s for Qantas and also has the PMDG NGX, he will no doubt give you an indication of how close PMDG have modeled this to the real deal.

 

https://www.facebook.com/Flap30greenlight/

[JoeDiamond 67]

Just got to MIA on an AAL 737-800. We rode the speed brakes off and on from cruise on down, and under 10,000, we had Flap 1 and 5 soon after. Speedbrakes used off and on all the way until turning onto the LOC.

 

http://flightaware.com/live/flight/AAL1083/history/20160308/1100Z/KIAD/KMIA

 

That's just another typical day in MIA.  Quite often it's 230 knots, flaps 5 with the speed brakes out all the way down.  Worse case scenario there is coming in from the west and landing straight-in to the east.  They like to keep you high, but that's OK because they also keep you fast. 

[vc10man 732]

Nope - certain STARs are steeper than others. Add slippery plane and you get a need for more speedbrakes, possibly...

Thanks for that, Kyle. Learn something everyday.

 

Rick Wilson, thanks for that link. Interesting read.

[scandinavian13 5,192]

That's just another typical day in MIA.  Quite often it's 230 knots, flaps 5 with the speed brakes out all the way down.  Worse case scenario there is coming in from the west and landing straight-in to the east.  They like to keep you high, but that's OK because they also keep you fast. 

 

ha - yep. I appreciated it a little more having flown it several times in the sim. Luckily, it was HILEY6, landing East, so they had the long downwind and vectors to get down and slow down.

 

Coming out of cruise:

 

Next step down in altitude:

 

Flaps out to drag down under 10:

 

Rollout pic for completeness (C-32 in the background for effect):

 

[Full size version of the last pic in case anyone wants to see the C-32 more clearly - be aware, it's 3024x4032]

[Bobsk8 12,489]

Energy management is one of the big struggles pilots have with the 800. I've jumpseated on the 737 a number of times, and it's been something that the captain comments on every time in the approach briefing. I've also seen the speed brakes used extensively in the descent. If they're planning on a short approach, then they'll sometimes drop the gear early to help in getting slowed up.

 

High energy approaches are also something I keep in mind as a controller, and we've been told to be keenly aware of the workload that it can put on pilots. If I have a sequence where I can put a 737 on a short approach, I'll look at the type. If it's a -400 or -700, then I can usually get them in pretty tight without any problems. If it's a -800 or -900, then I'll think twice before trying to set them up for a tight approach. 

 

If you want to get a taste of how energy management works in the real world, next time you fly an approach hold 210 kts to a 15 mile final, and then 170 to the FAF. This is typically how we set aircraft up on the finals here at IAH. It can be challenging, but I find it to be a satisfying way to fly approaches.

 

I live near Atlanta airport and listen to Atlanta Final Approach on Live ATC, and those are the usual instructions, 210 to around a 15 mile final slowing to 170 at the FAF. Repeated day in and day out. 

[scandinavian13 5,192]

Remember, flaps are used to slow down the aircraft and speedbrakes are used to increase drag. We do not use flaps as drag devices, therefore use “Flaps to Slow Down and Speedbrakes to Go Down!”

 

Flaps are used for:

1. Lift
2. Drag

There is a crossover point where the flap will produce more drag than lift, but an increase in lift means there's a corresponding increase in drag. See induced drag. For a more basic example, think of why we need a rudder for turns (the increased lift on the up-side wing requires rudder force to counteract the increased drag caused by that increase in lift).

 

The speed brakes on most of the jets of today are not speed brakes as much as spoilers. As such, they're not there for drag as much as killing lift, which steepens descents simply by causing the wing to not do its job as effectively.

[Usmcmba 4]

This is an interesting topic and luckily I am meeting couple of my coworkers tomorrow who are 777x wing engineers and I shall ask them just how much those speed breaks have in reducing airspeed in flight. Although, from Kyle's photos of the speed breaks being deployed in flight, I can't think it would slow you down that drastically with only two panels. From my flight training, slowing down an aircraft is always throttle back and nose up if you want to really slow down.

 

And by the way, flaps are never to be used as a way of slowing an aircraft down, the real purpose of the flaps are to change the camber of the wing so to lower your stall speed so you can land at a slower speed, or to provide more lift at take off depending on flap settings.

[scandinavian13 5,192]

Although, from Kyle's photos of the speed breaks being deployed in flight, I can't think it would slow you down that drastically with only two panels. From my flight training, slowing down an aircraft is always throttle back and nose up if you want to really slow down.

 

Those panels spoil a decent amount of lift. The result is an increased descent rate, which, if you pull the nose up to maintain your original descent rate results in a reduction in speed. You were on your way to that conclusion, but just got stuck on the panels causing drag, and not so much the panels killing lift, requiring a pitch up, which causes drag.

[Usmcmba 4]

Kyle, you are correct and I should have been more clear in the previous post. Speed breaks are really lift killing devices hence they all deploy when you land so to prevent the possibility of "ballooning". Either way, to truly slow down an aircraft is back to basics, throttle down and nose up. In complex aircraft you have more tools to help like speed breaks.

[ALF1 15]

Yeah, arriving KMIA from the Q routes over the gulf are the same way especially landing East. It's interesting that the pros are using Flap 5 for drag since that's still in the buoyant range, Flap 10 hits the drag.  I've always relied on dropping gear rather than flaps so yes, very interesting.

Doggone high performance singles and twins are almost impossible to bring down without the gear out Dan. I really love the Bonanza´s 156 KIAS gear extension speed for this, especially when in IMC, more control of the airplane. Having said that though, airline pilots I´ve heard really don´t want to bring that gear down until 7-10 miles out. Usually it goes along flaps 15 and speedbrake armed. I like to use Flaps 10 on steep approaches without the gear out it works pretty darn neat. It is a non standard setting I wonder why.

Energy management is one of the big struggles pilots have with the 800. I've jumpseated on the 737 a number of times, and it's been something that the captain comments on every time in the approach briefing. I've also seen the speed brakes used extensively in the descent. If they're planning on a short approach, then they'll sometimes drop the gear early to help in getting slowed up.

 

High energy approaches are also something I keep in mind as a controller, and we've been told to be keenly aware of the workload that it can put on pilots. If I have a sequence where I can put a 737 on a short approach, I'll look at the type. If it's a -400 or -700, then I can usually get them in pretty tight without any problems. If it's a -800 or -900, then I'll think twice before trying to set them up for a tight approach. 

 

If you want to get a taste of how energy management works in the real world, next time you fly an approach hold 210 kts to a 15 mile final, and then 170 to the FAF. This is typically how we set aircraft up on the finals here at IAH. It can be challenging, but I find it to be a satisfying way to fly approaches.

Gotta love these contributions from you folks...thanks so much sir.

From a line training manual! Never mean't me

Vernon, mainthing to remember is they both add drag, but flaps also increase lift. Spoilers or speed brakes kill lift by spoinling the airflow on the wings upper camber. Flaps actually augment this camber and allow the airplane to fly slower.

 

I insist that you would really benefit if you can sign up for a real ground school course which does not cost much.

[Steve Dra 7,557]

I swear you guys are doing it all wrong!

I've jump seated many times in a variety of airliners and I've seen the crew hit the Y key then F1 when they get a decent command that is out of the limits of the airframe or will make them bust a restriction.

Just hit Y again when you're at your desired altitude and you're all set.   Sheez. :rolleyes:

 

If you guys would just learn to use all the equipment on your aircraft, half these conversations/debates would never happen! 

[Spin737 102]

Only siths and simmers deal in absolutes. Flaps add lift and drag.

 

If I am at 210 knots clean, I can descend at 1100fpm, or so. If I go to F1, I can do 1500fpm. Something is causing that increased ROD.

 

You get a higher C_L with flaps, but you also get a higher C_D.