A320
Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 150; Flight Crew Total 21100; Flight Crew Type 5732
Aircraft Equipment Problem Less Severe; Deviation - Altitude Crossing Restriction Not Met; Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew FLC Overrode Automation
Aircraft
Cleared to descend via the DRLLR landing 26R. 6000 set correctly in FCU window. DES mode used. Both pilots separately and completely checked each altitude restriction. Two separate times PF had to use full speed brakes for altitude corrections; and waypoints correctly showed orange indicating crossing problems. At our request ATC cleared us runway 27 by descending via the DRLLR4 runway 27 except maintain 6000; and after DOMNO fly heading 085. PF changed runway to 27. As the PM returned from a PA announcement; it was noted the PTROL intersection was crossed about 10;700 ft in the DES mode. The correct altitude is between 11000-13000 ft. The PF disengaged the A/P and leveled off. The occurrence happened in DES mode with no deviation from descent path and no orange waypoint.
[Report narrative contained no additional information.]
A320 flight crew reported the FMS descended below one of the intersection fix altitudes while in descent mode on the DRLLR4 Arrival to IAH. Crew disengaged autopilot and returned to STAR clearance.