A319
Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 200; Flight Crew Total 24000; Flight Crew Type 8000
Confusion; Human-Machine Interface; Workload
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Overcame Equipment Problem
Human Factors; Aircraft
Cleared to Descend Via SKNRD3 Arrival into IAH. Prior to descent; both pilots checked the restrictions on the arrival with the FMGC. All in agreement. Descent started. First restriction at BEATL was between FL240-280. However the PFD showed the constraint as FL280 and leveled off rather than descending through the altitude window. This was repeated at DOOBI and SKNRD. Each time the constraint was double checked; but the airplane thought the restriction was a hard altitude. This caused doubt as to whether the airplane was going to meet the subsequent restrictions. Workload was increased and at one point; the flying pilot had to disconnect the autoflight and hand fly the descent. We even went to one of the restrictions and changed the window to a mid-altitude; for example: FL240-280 became FL260. Also during the descent we went out of DES into OPEN DES. Which now meant the bottom altitude needed to be changed to the most restrictive altitude instead of the bottom altitude of Descend Via. It seems this is happening frequently into IAH. It is odd; because the FMGC has the correct constraints; but the autoflight is flying it differently.
A319 Captain experiences FMGC anomalies during descent on the SKNRD3 arrival to IAH. Although the FMGC shows the correct altitude window at each waypoint; the PFD shows only the upper limit and the autopilot choses to level off there at each fix.