Reverse thrust at STN / EGSS

[OutOfRunWay]

Question from a bus driver

I always thought that all boeing autobrakes used a fixed braking force for a given autobrake setting, not like the bus which will produce a fixed deceleraton, modulating the brake force if reverse is used.

Please correct me if Im wrong.

regards,
OORW

[BYALPHAINDIA]

We don't use RT much now at TOM.

[barit1]

I always thought that all boeing autobrakes used a fixed braking force for a given autobrake setting, not like the bus which will produce a fixed deceleraton, modulating the brake force if reverse is used.

Please correct me if Im wrong.

Putting the shoe on the other foot -

Wouldn't it be nice if power management for TO was always set to achieve a known acceleration rate, based on R/W length and Vr (or some other speed)? You'd never be in coffin corner for TOGW error, brakes dragging, etc.

[BYALPHAINDIA]

Yes see what you mean, The T/O rate depended on the RWY length available, it would have been a good idea.

[miss_heard]

Wasn't Ryanair, was it?

no, the other one

[CL300]

barit1

Join Date: Feb 2005
Location: flyover country USA
Age: 66
Posts: 2,138

Wouldn't it be nice if power management for TO was always set to achieve a known acceleration rate, based on R/W length and Vr (or some other speed)? You'd never be in coffin corner for TOGW error, brakes dragging, etc.

yep this is called flex take Off...and you have a stopwatch for acceleration at 100 Kts..

[POL.777]

OORW:
Boeing Autobrakes senses deceleration rate and modulates brake pressure accordingly. Application of reverse thrust will result in reduced braking pressure.
On the 737 NG the autobrake settings available are 1/2/3/max and RTO.
1 is equal to 1250 PSI and 4ft/sec scheduled deceleration
2: 1500 PSI 5 ft/sec
3: 2000 PSI 7.2 ft/sec
Max: 3000 PSI 14ft/sec above 80 kts. 12 ft/sec below 80 kts
RTO: 3000 PSI