Narrative:

On descent; we armed auto-brakes to low. Then we got a brakes bscu CH1 fault ECAM. We accomplished the ECAM and continued the descent. Since a failure of only one channel of the bscu does not affect the braking system at all I did not see a need to try a system reset. In fact; the airbus is routinely dispatched with one channel of the bscu inoperative. On initial contact with approach we were given the right runway and I deselected the auto-brakes since I was going to have a longer roll to desired high speed. On landing; full reverse was applied and I noticed out of the peripheral vision that the wheel page was displayed and something was written in amber. I applied brakes pressure and the aircraft responded but in an unusual manner. We exited the runway and I reapplied the brakes; but needed much more than normal pedal depression to get any braking. I then looked closer at the wheel page and noticed a green 'altitude brakes' and amber 'automatic brks' indication and saw that the brake pressure indications on the accumulator gauge were in fact reacting to my brake inputs; which indicated a failure of the entire normal brake system. I slowed the aircraft and using the 'a' skid/NWS switch; reset the system and normal braking returned. My fundamental question is; how did the failure of just one bscu channel cause the system to revert to alternate brakes? Why did we get no other ecams or warnings that we had lost normal braking? If this had occurred on a short runway with slippery conditions the outcome could have been different.

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Original NASA ASRS Text

Title: An A320 Captain experienced a BSCU CH1 fault when autobrakes are armed during approach. During landing it was discovered that only alternate brakes were available. The A SKID/NWS switch was used to reset the system.

Narrative: On descent; we armed auto-brakes to low. Then we got a brakes BSCU CH1 FAULT ECAM. We accomplished the ECAM and continued the descent. Since a failure of only one channel of the BSCU does not affect the braking system at all I did not see a need to try a system reset. In fact; the Airbus is routinely dispatched with one channel of the BSCU inoperative. On initial contact with Approach we were given the right runway and I deselected the auto-brakes since I was going to have a longer roll to desired high speed. On landing; full reverse was applied and I noticed out of the peripheral vision that the wheel page was displayed and something was written in amber. I applied brakes pressure and the aircraft responded but in an unusual manner. We exited the runway and I reapplied the brakes; but needed much more than normal pedal depression to get any braking. I then looked closer at the wheel page and noticed a green 'ALT BRAKES' and amber 'AUTO BRKS' indication and saw that the brake pressure indications on the accumulator gauge were in fact reacting to my brake inputs; which indicated a failure of the entire normal brake system. I slowed the aircraft and using the 'A' SKID/NWS switch; reset the system and normal braking returned. My fundamental question is; how did the failure of just one BSCU channel cause the system to revert to alternate brakes? Why did we get no other ECAMs or warnings that we had lost normal braking? If this had occurred on a short runway with slippery conditions the outcome could have been different.

Data retrieved from NASA's ASRS site as of April 2012 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.