Originally Posted by
Kirks gusset
The Autobrake settings equate to pressures:
• Autobrake setting 1 - 1250 PSI equates to 4 ft per second squared.
• Autobrake setting 2 - 1500 PSI equates to 5 ft per second squared.
• Autobrake setting 3 - 2000 PSI equates to 7.2 ft per second squared.
• Autobrake setting MAX and RTO - 3000 PSI equates to 14 ft per second (above 80 knots) and 12 ft per second squared (below 80 knots).
If the autobrake is stopping you too quickly, then it's easy to as the PM to select a lower setting, or simply gently apply brakes until the disarm like comes on, at this point you will have the same pressure as the system, conversely if more stopping is required either select a higher setting or apply brakes gently and increase the pressure. The common mistakes are jolts from over ambitious disarming via the switch or stamping on the brakes.
Remember some landing conditions dictate the use of autobrakes so its not a personal choice
Its much safer usually to manually brake to make the required adjustments rather than have heads down in the cockpit,
Forgive me, but how can a brake pressure in PSI possibly equate to a specific deceleration rate? Wind, weight, touchdown speed... They're all going to affect that MASSIVELY. Surely the autobrake setting modulates brake pressure to give the desired deceleration rate upto the max brake pressure? I'm not saying it doesn't apply that specific pressure in PSI but there is no way that a pressure can remotely guarantee a deceleration rate - even on the worlds most perfect and dry runway.