A319
Flight Crew Air Transport Pilot (ATP)
Workload; Human-Machine Interface; Situational Awareness; Distraction
Deviation - Altitude Crossing Restriction Not Met; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy; Flight Deck / Cabin / Aircraft Event Other / Unknown
Flight Crew FLC Overrode Automation; Flight Crew Returned To Clearance
Human Factors; Chart Or Publication; Aircraft; Procedure
We were initially assigned the KIPPR 1 RNAV STAR (northeast gate; landing south) and had verified all altitudes and speeds. Just before CAAST we were re-assigned the ANCHR 1 arrival (northeast gate landing north). Again; both crew members verified all crossing restrictions on the arrival. Before TOD (Top of Descent) the First Officer managed the descent (speed managed).The Aircraft intercepted the profile and started down. At FL350 the restriction at LYUNN went amber. The First Officer took control via the Flight Control Unit (FCU) and worked to bring the aircraft back on profile. We crossed LYUNN at approximately FL343. To make the restriction at LBSTR required speed brakes; an increase in speed (selected); and the use of open descent (OP DES). We reestablished the profile just before LBSTR. The profile required significant and constant input to insure the restrictions were met. The complexity of these new arrivals and the tendency of ATC to modify these Denver RNAV arrivals increase the workload dramatically and create a constant change in automation between fully managed; vertical speed; selected speed; and open descent to meet the restrictions.
In short; the autopilot will not comply with what is displayed on the Flight Management and Guidance Computer (FMGC) and the aircraft must be flown in selected modes in order to comply with published restrictions.The problems began at LBSTR. This waypoint is published at or below FL320 (programmed -32;000 on the FMS). For unexplained reasons the aircraft imposed upon itself a crossing limit of exactly FL320 despite being programmed 'at or below'. During descent; the autopilot began an unnecessary level off at FL320. As the autothrust system increased power; the autopilot was overridden by the crew; and an unrestricted descent was selected. Even with spoilers deployed; the aircraft crossed LBSTR 300 feet high. Similar problems continued at the waypoints of LIBIE and ANCHR. Once past ANCHR however; the autopilot was able to comply with the restrictions without further input from the crew. The new procedures have decreased; not increased; or levels of safety in that pilots are continually worried about compliance with numerous restrictions and will sometimes miss radio calls and disregard traffic vigilance. Our eyes and brains are more often 'inside' rather than 'outside' the airplane. We know from previous experience that the Airbus will do a fine job on the arrivals at LAX; ABQ and PHX just to name a few. Also; from a standpoint of energy management the new arrivals are perfectly workable. But due to some unknown reason or reasons; certain new procedures into DEN cause our autopilots to simply not comply with what has been programmed and verified in the FMS.The Captain and I discussed the merits and drawbacks of actually refusing any of the new arrivals until the problems have been discovered and corrected.
Despite having programmed and verified all altitudes and speeds when assigned the ANCHR RNAV STAR to DEN the flight crew of an A319 was compelled to override the FMGC descent path commands to comply with charted crossing restrictions.