Realstic Stopping?

[badderjet 181]

Hey guys. I will try to give you the skinny on the autobrake system.[...]

Wow, thanks for that. Are the decel rates to be found in any manual anywhere? I think it's interesting that MAX has yet twice the decel rate of the second highest setting, 3. In

I believe they are using MAX, but it's hard to tell for sure. Nice to see how he plants her down right after the numbers without flaring a great deal. If you ever felt a brake 3 landing, which isn't really uncommon, then I can only imagine how a MAX landing would be like. Although in this particular video the DISARM light comes on pretty quick after touchdown so maybe they decided to brake manually here.Now I'm curious though - MAX will still modulate brake px in order to achieve 14 ft/s², right? So I suppose if you were braking manually, you should be able to achieve even higher decel rates, correct?

[Tabs 2,790]

Yeah I think that's manual braking in the SBRJ video - no way DISARM should come on that quickly otherwise.

[badderjet 181]

Yeah I think that's manual braking in the SBRJ video - no way DISARM should come on that quickly otherwise.

Yep true. I was just thinking (by looking at the switch, which seems to be pointing to MAX) that this runway is so short as to justify a MAX autobrake setting, as I've never seen that setting used anywhere else. Where would I look that up anyways, whether to use 1, 2, 3 or MAX? I'm sure this is not solely depending on runway length, is it?

[f.leite 0]

That is for sure MANUAL braking. The procedure to use if you want maximum braking is to select MAX autobrake to ensure that as soon the MLG touches the ground the brakes are aplied and when suitable aply maximum manual brakes from the pedals and let the anti-skid do its job.

[badderjet 181]

That is for sure MANUAL braking. The procedure to use if you want maximum braking is to select MAX autobrake to ensure that as soon the MLG touches the ground the brakes are aplied and when suitable aply maximum manual brakes from the pedals and let the anti-skid do its job.

Of course it is. Thanks however for the procedural explanation, that makes a lot of sense. And leads to two more questions:I agree that MAX autobrake would apply pressure to the discs as soon as there is ground contact, but I seem to remember there would be a delay with the lower settings. Is that true, and can there be found any reference?Next question, is it possible to apply brake pressure AND/OR P/BRK in flight (well of course you can apply brake px, I just want to know if it reaches the brakes when not on ground...)? Or is there a control logic that prevents touching down with any brake px at all? I believe the 'buses prevent that, but I dunno about the Boeings. Would be cool if someone had good info on that.

[VIPERGTSR01 22]

Next question, is it possible to apply brake pressure AND/OR P/BRK in flight (well of course you can apply brake px, I just want to know if it reaches the brakes when not on ground...)? Or is there a control logic that prevents touching down with any brake px at all? I believe the 'buses prevent that, but I dunno about the Boeings. Would be cool if someone had good info on that.

Not sure of the answer, I would assumed there would be logic to prevent the parking brake to be applied in flight/touch down but I remember a video on youtube of a guy who got the opportunity to fly a level D MD-11 simulator, as a joke someone (a rated pilot) set the parking brake on as he was on final approach, the guy landed and the plane went into a sudden uncontrollable skid, crashed and took the guy flying totally by suprise. Maybe it is possible or maybe they made it possible for that instance. From memory you can land with parking brake applied on the PMDG MD-11 also but the result wasn't so dramatic.

[Joel 10]

Not sure of the answer, I would assumed there would be logic to prevent the parking brake to be applied in flight/touch down but I remember a video on youtube of a guy who got the opportunity to fly a level D MD-11 simulator, as a joke someone (a rated pilot) set the parking brake on as he was on final approach, the guy landed and the plane went into a sudden uncontrollable skid, crashed and took the guy flying totally by suprise. Maybe it is possible or maybe they made it possible for that instance. From memory you can land with parking brake applied on the PMDG MD-11 also but the result wasn't so dramatic.

I wonder how he missed the engaged parking brakes!

[badderjet 181]

I wonder how he missed the engaged parking brakes!

Well it was obviously

.

[JaneRachel 530]

Fantastic explanation! Thank you very much.

I should also point out when you hear the term "idle reverse", this actually refers to my parking my car and is not related to aircraft as people wrongly assume. I am way too idle to reverse into a parking spot! Any reference to NON-NORMAL checklists actually refers to why the parking space suddenly appeared smaller when I tried to reverse into it and what checklists I should follow for reporting the damage to the car behind me whilst some irate guy is looking at his bent car and telling me I am not normal. ;)I would work my way through a lot less cars if they had the benefit of a pushback tug at my supermarket too!JR

[xxJohnxx 21]

Well it was obviously

.

It looks like this MD 11 simulator has got an HUD. So I think some airlines have that in their MD 11. Does anybody know which airlines have equipment? And why the PMDG MD 11 doesn't has an HUD ? *just kidding*Best regardsJohn

[KriVa 307]

The HUD in the MD-11 was developed for FedEx, if I remember correctly.You can even see the camera for it in this forum thread, it's located just beneath the Captain's front window: http://tinyurl.com/3wevc9kAnd of course, a little demo on YouTube:

[xxJohnxx 21]

Hi Thomas,Thank you for that information! Would have been nice for the PMDG MD. Best regards,John

[MrKen 3]

14 fps is some pretty serious braking. That's a shade over 0.4 g's

[badderjet 181]

14 fps is some pretty serious braking. That's a shade over 0.4 g's

I wonder what an average car makes? Is an RTO worse than a hard braking in my car? Oh and BTW, speaking of RTOs, does RTO (the autobrake setting I mean) in fact apply just the maximum brake pressure it's got, or is there also some sort of predetermined decel rate? I'd suspect the former but I don't know for sure off the top of my mind.

[MrKen 3]

I wonder what an average car makes? Is an RTO worse than a hard braking in my car? Oh and BTW, speaking of RTOs, does RTO (the autobrake setting I mean) in fact apply just the maximum brake pressure it's got, or is there also some sort of predetermined decel rate? I'd suspect the former but I don't know for sure off the top of my mind.

A formula 1 racer, with the additional downforce induced by the car's design & special compound tires can experience up to 4g when stopping.Your average sedan with run-of-the-mill tires on normal pavement is around 0.6g I believeGiven the balance of an airliner on the ground, steering sensitivity when braking & the consequences of losing control, 0.4g is still pretty quick.I could be wrong, but I believe RTO gives maximum braking regardless of spoilers/reverse thrust