Speed brakes are very effective IRL on the 78 especially compared to the 73 or even the 75 or 76. 
 

I think there’s an issue with the ops set up tbh. On the PMDG you’d notice a difference with the speed brakes deployed on the 73 and definitely on the 777. 

18 hours ago, ckyliu said:

Just because it's not certified, doesn't mean it's impossible - just no one had the need to pay out for that certification. Flap 40 is very draggy so I'm not surprised and it is likely possible IRL albeit maybe not within certification criteria, as being certified for the 5.5 deg glidepath means actually being capable of a steeper descent to counteract deviations from the glidepath.

Use of wing speedbrakes/spoilers during approach is a big no-no unless the aircraft is suitably certified - the A318 deploys them during steep approach through use of a special switch that changes the flight control logic and EGPWS, and retracts the spoilers automatically. Same goes for the E-jets. Both typres required some minor adaptions to earn certification.

To be fair, I was comparing it to how the aircraft behaved at this airport in P3Dv4. In that simulator, I had to deploy full speed brakes just to keep the plane at 130 knots during the descent on that 5.5 degree glide slope.

Please note that my flap setting is 30.

Edited October 26, 20241 yr by Christopher Low

On 10/25/2024 at 7:43 PM, ahsmatt7 said:

I don’t actually have an axis programmed but I do have switches being used on my thrust lever set up.

 Does the keyboard binding have any negative effect as well? 
 

I will say that I use the keyboard button (/) predominantly over my calibrated joystick button. 
 

I’ll try that this weekend on my trip. I use a laptop at work and I wonder if the problem persists on the laptop considering I use the Xbox controller and no other controllers. On the contrary, my home set up uses the HOTAS warthog.

Yeah so any hardware in MSFS will override the software no matter what you do. The position of the hardware switches will not tell us they're overriding anything either, so what likely happens is your hardware switch is setting the spoilers to down. You pull the spoilers using the software, everything gets activated as if the spoilers are in fact engaged, and then the core FM itself does not deploy the spoiler because it is being forced off by the hardware, despite all the software showing the contrary. Happens often in flap axis too, and worst of all is when someone has a mixture axis set - and there's a bit of axis noise. It will kill the engines. 

Edited October 26, 20241 yr by Aamir

5 hours ago, Aamir said:

Yeah so any hardware in MSFS will override the software no matter what you do. The position of the hardware switches will not tell us they're overriding anything either, so what likely happens is your hardware switch is setting the spoilers to down. You pull the spoilers using the software, everything gets activated as if the spoilers are in fact engaged, and then the core FM itself does not deploy the spoiler because it is being forced off by the hardware, despite all the software showing the contrary. Happens often in flap axis too, and worst of all is when someone has a mixture axis set - and there's a bit of axis noise. It will kill the engines. 

Thanks for the thorough explanation!

Just to recap, disable any assignments to spoilers, then click and drag the spoiler lever in the vc and see what happens?

If everything works with the above method? Is is just better to not have anything assigned to the spoilers?

2 hours ago, ahsmatt7 said:

If everything works with the above method? Is is just better to not have anything assigned to the spoilers?

You can assign stuff, just make sure it's an axis and calibrate it in the MCDU so systems are on the same page.

Lemme know if this works, if it doesn't I'd reach out to support for a bit of help - or post a video showing what you mean by poor deceleration so I can take a look and see if it's normal or not. 

Just adding to the conversation on speed brake use for anyone interested in these things.

On the 747 the speed brakes weren’t used as much. If being kept at cruise altitude beyond the calculated TOD point we’d wind the speed right back, the if you can’t go down, slow down principle.

Then when cleared to descend we’d wind the speed up to 330kts after getting HOLD on the auto throttle, the big beast would then dive like a house brick.

On levelling out you could wind the speed back to 250 and she’d sit at idle for about 10 miles in level flight effectively gliding while she decelerated.

When the brakes were used it caused quite an abrupt nose down pitch in their last couple of inches of lever travel.

Other than that there were obviously times closer in when speed brakes may be needed to tighten things up , but generally there was so much aerodynamic braking available compared to other aircraft on the 747 that the brakes weren’t used as much.

It was part of 747 culture that when the brakes were used either the pilot or ATC had messed up, and it was a lever of shame.

Oh how I miss flying that big old machine.

On 787 conversion the ex 747 guys were keen to emphasise that the brake lever was not a lever of shame on this aircraft and its use was required early. And they were right, the thing is like a glider, the FCTM has a table of figures which shows slow speed with brakes out will out descend a high speed clean descent like we used on the 747.

Edited October 27, 20241 yr by jon b

I have only ever had one flight on a 747 (London Heathrow to San Francisco in 1995), and it came in over San Pablo Bay as quiet as a mouse!

Then when you dangled 18 Dunlops, plus the barn doors, out in the breeze, she was a brick. The 747-200 used to do this as part of the emergency descent non-normal procedure, but the 747-400 never did, instead opting to keep the gear up.

On 10/27/2024 at 3:39 AM, jon b said:

It was part of 747 culture that when the brakes were used either the pilot or ATC had messed up, and it was a lever of shame.

This mentality exists with certain cadres of pilots on every fleet in the industry, and those of us in standards and training have been fighting it for years.

If there weren't valid times to add drag to the airplane, Boeing would not have put that handle in it.  Does it really matter if either the crew or ATC screwed up, or it's a situation that happened another way?  Maybe it's better to just solve the problem. 

Sure, winding the speed up in the descent is the easy answer, if you're not speed restricted.  But more and more STARs are, these days, with a published indicated to transition to.  Difficult to fix a high on those procedures without drag.

The whole "handle of shame" thing really needs to go away.

Don’t worry, if and when the speed brake was needed it was used, no one was actually sat there tutting if someone grabbed the speedbrake lever.

My point being that because the 747 had such good aerodynamic braking because of its profile compared to other aircraft, it wasn’t used as much. We had another way of skinning that particular cat available to us by using the aircraft’s drag and huge inertia to our advantage. And converting the excess height to speed was more efficient than just sat with the brakes out.

Certainly it was easy for those new on type from smaller aircraft to get behind the aircraft’s inertia and the spoilers were required more often. Those of us who had been flying the 747 for decades were able to manage the energy without much difficulty.

Of course for close in work we used the spoilers where you were tied to speed and profile , I was talking more about initial portions of the decent,

On 10/26/2024 at 10:07 PM, Aamir said:

You can assign stuff, just make sure it's an axis and calibrate it in the MCDU so systems are on the same page.

Lemme know if this works, if it doesn't I'd reach out to support for a bit of help - or post a video showing what you mean by poor deceleration so I can take a look and see if it's normal or not. 

Update…

I flew the a320 variant when doing those tests. I deleted any assignments to my spoilers except the ‘/‘ key. 
 

I moved the physical lever in the cockpit with my mouse. Everything works as expected. I then used the keyboard assignment of ‘/‘ and everything works as expected.

 

Once again, thank you for the help!