A330
Flight Crew Air Transport Pilot (ATP)
Confusion; Human-Machine Interface; Situational Awareness; Communication Breakdown
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy; Flight Deck / Cabin / Aircraft Event Other / Unknown; Ground Event / Encounter Loss Of Aircraft Control
Flight Crew Overcame Equipment Problem
Human Factors; Airport; Procedure
Taxied into the [international] gate on arrival following self guidance system. Stopped when indicated and waited for an 'OK' indication to shutdown. Received the 'OK' then proceeded with shutdown procedures. During my flow I looked up again to see 'INBLK.' I have never seen this on any other system and took it to mean that the aircraft was chocked. I released my foot pressure off the brakes and continued my shutdown. I knew that the jetway was in the process of moving backwards when the First Officer said that the aircraft was rolling backwards. I told him it was the jetway [movement] and he assured me it was the aircraft. I immediately applied the parking brake. The steep ramp gradient and my failure to set the parking brake prior to releasing the brakes [resulted in the aircraft rolling backwards.]From the pilot side of the equation I would suggest the following. I have spent years developing a habit pattern derived from the scrutiny of my fellow pilots regarding the [need to] capture every flight minute possible. This has included the use of the parking brake which triggers in and out times. I have held short of active runways straining to hold the brakes and scared to death of accidentally releasing them. I have even had my fellow pilots remind me not to set the brakes but to wait for a door to be opened hoping to capture another minute. I have gone ahead and set the parking brake only to be chewed out by other pilots. So I am forced to unlearn a bad habit; relearn a new one; and ignore the wishes of my contemporaries. Another input on the A330 is brake temperature and the ECAM warning hastened by the application of the parking brake.From the other side of the equation: We should have a better system for [block] time capture. I understand that brake [cooling] fans were an option that was turned down by the company. This airport obviously has a problem that they seem to want to shift onto someone else. I understand we normally park at C [concourse] but instead was parked at B where the gradient may be even worse. Knowing the problem; the airport and station personnel should be more proactive in contributing solutions. The guide in system should have 'INBLK' removed to avoid confusion. The aircraft needs to be chocked immediately in multiple locations. A marshaller should be there to give the pilot a 'chocks in' signal and a 'set brakes' signal.
After arriving in the gate an A330 Captain; holding brakes manually to preserve extra block to block minutes prior to 'setting the parking brake'--thus triggering the flight crew's block in time--was surprised when he misinterpreted the meaning of a self-park lighted advisory acronym to mean the nose gear had been chocked. He then released the brakes. He was quickly alerted by his First Officer that the aircraft was now rolling backward on the sloped ramp and then re-stopped the airplane and set the brakes properly.