A300
Human-Machine Interface
Aircraft Equipment Problem Less Severe; Deviation - Altitude Crossing Restriction Not Met; Deviation - Altitude Undershoot; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Weather / Turbulence
Flight Crew Requested ATC Assistance / Clarification
Aircraft; Human Factors; Weather
Cleared to descend via PHLBO3 RNAV Arrival into EWR for an ILS 04L approach. Captain was pilot flying. Used max automation due to poor weather. Autopilot Number 1 was engaged with NAV and Profile selected. We made the SOMTO Intersection crossing restriction at 11;000 FT with no problem. Shortly after SOMTO we still had a tailwind and also encountered an area of heavy rain and moderate turbulence. We were night IMC conditions with engine anti ice on and static electricity on the windshield. Captain disconnected the autopilot and manually began flying the aircraft when he realized the FMS in Profile mode would not make the crossing restriction at DYLIN of 8;000 FT. Had he allowed the autopilot and profile to stay engaged it probably would have crossed DYLIN at least 1;500 FT high. First Officer called ATC and told Controller we were in heavy rain with moderate turbulence and that we crossed DYLIN intersection 500 FT high. No traffic was noted on the TCAS within a 12 mile range; we had no loss of separation; and Controller didn't say anything about it. He gave us a vector to final approach for ILS 04L. Profile mode in the Airbus apparently cannot handle strong tailwinds; updrafts and turbulence. In retrospect; one level less of automation might have helped (using level change with step down altitudes); but the situation we encountered would probably still have required an autopilot disconnect.
An A300 First Officer reported crossing DYLAN high on the PHLBO 3 RNAV arrival due to strong tailwinds and turbulence. The Captain was the pilot flying using LNAV and VNAV. The autopilot was disconnected in an attempt to make the restriction.