Okay, so in recent times we've heard alot about how the upcoming PMDG 737 will have very realistic brakes modeled, going as far as to model the cooling difference between the carbon and steel brakes however in FSX we leave the park-brake set while at the gate, doing our turnaround, however IRL, we release the parkbrake once we're in position and the ground crew have the chocks inserted. This allows for quicker cooling of the brakes and prevents them sticking to the wheels on hot days. So I suppose I have two questions here;1. Probably obvious but will the difference in cooling rate differ on whether or not the park brake is set at th gate or if the park-brake is off and we have the chocks inserted?2. Will the chocks be modeled? Perhaps a selectable option in the FMC and if they are modeled will they function or will they just be for the visual effect as with other add-ons?Then another problem arises as in FSX when using Aerosofts AES, it requires that you leave the parking brake set so then in that case would it be possible to switch the cooling model to as if the brakes were off but still leave them set so AES can do its work?Thanks for your time, Rónán O'Cadhain.

AES doesn't require you to keep the parking brake on. As soon as the jet bridge or stairs are in place you are free to release the parking brake and nothing happens. I do it all the time with the MD11.

AES doesn't require you to keep the parking brake on. As soon as the jet bridge or stairs are in place you are free to release the parking brake and nothing happens. I do it all the time with the MD11.

Thats new for me thanks!

Interesting that you bring that up. About 8 months ago, after reading very detailed accounts of real life operations by airline pilots, I started to disable the parking brake at the gate. I didn't know about the brake cooling advantage, I just thought it made sense to disable it because parking brakes require hydraulic power, which of course is not available when you are sitting at the gate! Whenever I arrive at the gate, I will leave the parking brake on for about a minute or so, but then disable it after the ground crew notifies me that the chocks are in. They will remain off until pushback, after I activate the auxiliary hydraulic pumps.I'd go one step further than just simulating enhanced brake cooling with the "handbrake" off, how about having PMDG code the parking brakes to only operate when the hydraulics (or at least an an auxiliary pump) is online? I have a question, will the parking brake lever work when there is no hydraulic pressure? I presume the lever will move, but the actual brake won't work without pressurization. If that is the case, I guess it's not worth coding to change the FSX default behavior of parking brakes on or off without regards to hydraulic state.

A.J., for some reason I thought they had coded the need for hydraulic power for the brakes to work. But, if you push the brake key/button the sim will register the brakes working (even if they don't actually work), because the brake notification was hardwired in the sim. I could be wrong about this though.

A.J., for some reason I thought they had coded the need for hydraulic power for the brakes to work. But, if you push the brake key/button the sim will register the brakes working (even if they don't actually work), because the brake notification was hardwired in the sim. I could be wrong about this though.

I believe PMDG did code this correctly (hydraulic power as a prerequisite for parking brake) in the MD-11, and in the 747 there is the appropriate brake pressure gauge. So in essence PMDG has modeled this behavior correctly, I guess the parking brake logic is hard coded by Aces in FSX to always work, no getting around that. We will just have use this simulate this requirement by not activating the brake with hydraulics off, its a FSX limitation we have to work around.

I believe PMDG did code this correctly (hydraulic power as a prerequisite for parking brake) in the MD-11, and in the 747 there is the appropriate brake pressure gauge. So in essence PMDG has modeled this behavior correctly, I guess the parking brake logic is hard coded by Aces in FSX to always work, no getting around that. We will just have use this simulate this requirement by not activating the brake with hydraulics off, its a FSX limitation we have to work around.

Maybe a workaround is set up my not using the FSX command & mapping a key through the PMDG options? I'm not a coder by any stretch of the imagination, but it seems like that could work. then the addon decides something like "if hydpress >= whateverpsi then park brake = true, else false, that sort of thing..."That or just make sure an engine or the apu is running...

I have a question, will the parking brake lever work when there is no hydraulic pressure? I presume the lever will move, but the actual brake won't work without pressurization. If that is the case, I guess it's not worth coding to change the FSX default behavior of parking brakes on or off without regards to hydraulic state.

It depends. Many aircraft have an hydraulic accumulator in the parking brake system, which is pressurized by compressed nitrogen. The accumulator will provide sufficient hydraulic pressure to engage and hold the parking brakes, even with no other source of hydraulic pressure available. (Such as electric or engine-driven pumps.)One drawback is that the accumulator stored pressure can bleed off slowly over time, causing the brakes to eventually release, and will bleed off very quickly indeed if the parking brakes are released and re-applied more than a couple of times.I don't know, however, if the 737 has such a system.Jim Barrett

It depends. Many aircraft have an hydraulic accumulator in the parking brake system, which is pressurized by compressed nitrogen. The accumulator will provide sufficient hydraulic pressure to engage and hold the parking brakes, even with no other source of hydraulic pressure available. (Such as electric or engine-driven pumps.)One drawback is that the accumulator stored pressure can bleed off slowly over time, causing the brakes to eventually release, and will bleed off very quickly indeed if the parking brakes are released and re-applied more than a couple of times.I don't know, however, if the 737 has such a system.Jim Barrett

Correct, in most A/C we have accumulator powered brakes, they are used in event of a total hydraulic system failure or at the gate if there are no chocks available to hold the plane so we cn keep the Park-Brake engaged however, more ofter than not we don't need to keep it engaged.AFAIK with AES the chocks that they say are in position do not hold the aircraft in FS but i'd have to ask that over on the aerosoft forums.Any comment from PMDG?Thanks,Rónán O'Cadhain

AFAIK with AES the chocks that they say are in position do not hold the aircraft in FS but i'd have to ask that over on the aerosoft forums.Any comment from PMDG?Thanks,Rónán O'Cadhain

Correct, I don't think they do. That would be a nice feature. However after the chocks are in position AES doesn't check for the parking brakes to be set until you push-back again.

If I remember correctly, the parking brake on the MD-11 must not be activated during loading/unloading, because it can damage the gear. I don´t know if this is an issue with the much lighter 737. Anyway this is modeled with the FS2CREW/MD-11

Correct, I don't think they do. That would be a nice feature. However after the chocks are in position AES doesn't check for the parking brakes to be set until you push-back again.

But what should be in AES is a message from ground crew that allows you to release the brakes and then tells you to sett them again before push back so they can remove chocks...

If I remember correctly, the parking brake on the MD-11 must not be activated during loading/unloading, because it can damage the gear. I don´t know if this is an issue with the much lighter 737. Anyway this is modeled with the FS2CREW/MD-11

That is correct, some larger aircraft can't have the parking brakes set while loading and unloading. Don't know which ones now but the A330 and A320 can. I think the DC 10 also couldn't but I'm not 100% sure on that one not having flown on it. It all depends on whether or not the landing gear i straight or angled forward a bit to provide self centering nose gear as with the MD-11.

I guess the parking brake logic is hard coded by Aces in FSX to always work, no getting around that. We will just have use this simulate this requirement by not activating the brake with hydraulics off, its a FSX limitation we have to work around.

I don't think there is 'no getting around it'. If I recall correctly the brakes on the Smicheck A300 won't operate unless you've got the hydraulic system's pressure up first.Al

Many addons (most?) require hydraulics pressure to be able to activate the brakes, I'm sure the NGX will be like this as well