This has been a point of different views when it comes to checking brakes at the commencement of the Taxi-out phase of a flight.
On the A321 ( 320 Family) releasing the Parking Brake disconnects the Yellow Hyd Braking system and transfers braking to the Green Hyd system.
Is it better to release brakes let the A/C roll then smoothly apply brakes again.
Or by simply releasing brakes while holding the brake pedals for a brief period insures that the green hyd braking system is functional.
