They are in the Airbus... :wink:

 

Regards,

Ró.

 

Yep another brilliant design

 

 

Next logical question then ... for short runways, can you select RTO as the autobrake setting for a landing ?

Best to do would be select max auto to ensure the brakes apply right away and then you can use max manual after you've touched down.

Of course, then you'll have to explain why you have 12 deflated tyres.

 

Better 4 deflated tyres (remember this is 737 with RTO) than an aircraft down the river/sea/hill/whatever is after runway end. Sometimes it might just help, if you are for ex. landing with no flaps. I guess max manual would still work the same though.

Auto brakes helps to achieve more passenger comfort at landing roll IMO. It helps to keep a stable deceleration rate. AFAIK, when you hit reversers, autobrakes sets the pressure on the brakes and keeps the same amount of deceleration (in this scenario, it decreases the pressure on the brakes when reversers came into effect).

 

Please someone confirm if it is true.

 

Thanks.

AFAIK, when you hit reversers, autobrakes sets the pressure on the brakes and keeps the same amount of deceleration (in this scenario, it decreases the pressure on the brakes when reversers came into effect).

 

Please someone confirm if it is true.

 

Yes.

Now the real next question, is RTO better than max manual braking when aborting takeoff?

yes, since it does apply maximum pressure, all the time (your legs might fluctuate a bit), and activates quickly and automatically.

 

So basically, since max auto doesn't get the same rate as max manual on a dry runway, is basically just an in built margin to ensure that on contaminated runways there's still enough wiggle room to achieve the requested decel rate that was used for landing calculations.

 

That makes sense. I can't see why they wouldn't allow a little bit of "wiggle room" for the calculations...

Ben,

 

On contaminated runways the autobrake system fights with the anti-skid system as the autobrake will try and achieve a rated wheel rotational deceleration. If the wheels start skidding then the autobrake will release the brakes until the rotational deceleration selected on the autobrake system achieves the selected braking level. This can lead to some fairly noticable juddering on slippy runways and a fair addition to the landing distance required.

 

With max manual braking the anti-skid system will release the wheel until rotation starts again and then the manual brakes will clamp back on. It's a bit like the system in your car! It will judder like mad but stop you pretty quickly. Auto brakes are far smoother than my lead feet!

 

A couple of sim checks ago we used the short landing runway at Boston with a variety of surfaces and a variety of tail winds to show the effect of runway surfaces and tailwinds on landing distances. Suffice to say that a heavy 772 stopped pretty quickly with a dry surface and max manual braking! Most of the passengers would have been in the first galley mind you!

Just to clarify, here is the extract from the Fcom1:

 

 

On initial brake application the anti-skid system modulates the applied

brake pressure to determine the skid threshold. On detecting a wheel

deceleration, impending skid, the anti-skid system releases brake pressure

sufficient to avoid skid. Three or four releases will occur during the

process of determining the optimum brake pressure for the existing runway

conditions. When the brake pedals are modulated or re-adjusted for

additional or less braking this process is repeated. Braking effectiveness

during the readjustment period is reduced.

On slippery surfaces the optimum applied brake pressure is appreciably

reduced. The effect of the initial releases is more pronounced. The

varying runway surface conditions associated with ice and snow will result

in additional anti-skid system brake releases. These combined with the

reduced optimum brake pressure will significantly increase stopping

distances. Modulating the brake pedals will only aggravate the conditions.

Autobrake should be used when landing on slippery surfaces. If necessary

MAX autobrake should be selected on the autobrake control which will

give optimum braking during deceleration. On slippery runways the

autobrake system will not apply the brakes until the wheels spin up and

anti-skid locked wheel protection is established. MAX autobrake is only

available when the pitch angle is less than 1 degree.

At slower speeds especially on slippery surfaces, the effect of the anti-skid

system brake releases are even more pronounced.

 

Enjoy!

Most of the passengers would have been in the first galley mind you!

 

:lol: LOL!!

Talking about braking, is there any way to reduce the braking action, say, of a certain autobrake setting?

It seems to me the actual braking action is to high, which has been confirmed by friends of mine who actually fly the real plane.

Thanks!

Talking about braking, is there any way to reduce the braking action, say, of a certain autobrake setting?

It seems to me the actual braking action is to high, which has been confirmed by friends of mine who actually fly the real plane.

Thanks!

 

This isn't correct, actually.

 

The autobrake has been configured to decelerate using the Boeing supplied values. It behaves accordingly in the sim. I'm sure they might think it's different, but when it comes to what some random pilot said, or what Boeing says, I'm going to go with Boeing and the data.

Bear in mind with 737/777 comparisons that if Boeing had gotten it's way - the 737-NG flight deck would be identical to the 777. However SWA - the launch customer - wouldn't buy the NG unless it had backward compatibility with the older 737s. That's probably the reason for the 737 differences, more than any lack of consistency on Boeing's part.

This isn't correct, actually.

 

The autobrake has been configured to decelerate using the Boeing supplied values. It behaves accordingly in the sim. I'm sure they might think it's different, but when it comes to what some random pilot said, or what Boeing says, I'm going to go with Boeing and the data.

 

Hello Kyle,

 

I'm not a 777 rated pilot, but I have such friends that also have the PMDG 777.

It looks strange to me the fact that using Autobrake 1 (and no thrust reversers) the plane stops so quickly. Even for the shorter runways, say 2000 meters, I've incorporated into my routine to use only Autobrake 1, which will suffice for PMDG 777. And I'm not quite lightweight. My landing weight normally goes about 115~120 tons. A friend of mine who flies both the 77L and 77W in the real life have made some tests and also believed it was taking so little runway to stop, compared to the real one.

As for me, prior to flying the PMDG 777 I used to fly the 767 Level-D on FS2004, it was quite a change for me in this regard. There, if I used Autobrake 1, it would run all of a lengthy runway of about 4 km long... :-)

Thanks for your comments.