A321
Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Flight Crew Total 529
Aircraft Equipment Problem Critical; Conflict Ground Conflict; Less Severe; Ground Event / Encounter Aircraft; Ground Incursion Runway
Flight Crew Executed Go Around / Missed Approach; Flight Crew FLC Overrode Automation
Aircraft; Procedure
During approach for landing and fully established on the ILS Runway XXR at ZZZ. An A320 was given clearance to cross the landing runway from right to left when I was approximately 900 ft. AGL. Crossing aircraft was slow to cross and cleared the landing runway when I was 100-200 ft. AGL. During flare with thrust levers at idle the aircraft rolled uncommanded to the left. I countered the roll with right aileron correction and a balloon ensued. I chose to go around at that point; but due to energy state; engine spool up time and ground proximity the main landing gear touched down before becoming airborne again. Almost immediately after becoming airborne we got master caution alerts and ECAM advisories of flight control malfunctions. Being the Pilot Flying I maintained control and asked what was going on. FO (First Officer) informed me that the autopilot was inoperative and he believed us to be in Alternate Law. We cleaned up the aircraft and both verified the ailerons were inoperative on the F/CTL page and roll control was available via spoilers. The aircraft had reverted to Alternate Law and was verifiable by indications on the PFD.I gave FO the responsibility of flying the aircraft and ATC as I referred to QRH pg 62 F/CTL L(R) AIL FAULT. The procedure simply states that if both ailerons were deflected we would use more fuel. I did a landing assessment with our current state and verified we needed approximately 5700 ft. of runway. I [Requested Priority Handling] and since I had no idea why we were in Alternate Law; I felt the safest course of action was to return ASAP to ZZZ for a landing as opposed to trying a computer reset. I had full roll and pitch authority and didn't know what would happen if I tried to reset the computer; nor did I know which ELAC was inoperative. A normal approach and landing was made to Runway XXL. No limitations were exceeded. I attribute the whole scenario to the slowly crossing aircraft. I have never had an uncommanded roll in the flare during landing. From now on if a crossing aircraft has not cleared the landing runway by the time I get to 400 ft. AGL I will initiate a go around.
A321 Captain reported a go around after an uncommanded roll at 100 ft. AGL and loss of an ELAC.