BAe 125 Series 800
Flight Crew Air Transport Pilot (ATP)
Human-Machine Interface; Situational Awareness; Time Pressure; Troubleshooting; Workload; Confusion
Aircraft Equipment Problem Less Severe; Conflict Airborne Conflict; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance
Air Traffic Control Issued Advisory / Alert; Flight Crew Returned To Clearance; Flight Crew FLC Overrode Automation; Flight Crew Took Evasive Action
Environment - Non Weather Related; Aircraft; Weather
Flight was assigned RUUDY 4 departure. Procedure was briefed and FMS/Flight Director configured and verified correct. ATIS winds prior to taxi were 330 degrees at 8 knots. Winds provided with takeoff clearance were approximately 90 degrees from right and gusting to 24 knots. Immediately after liftoff the aircraft experienced light to moderate turbulence and began to drift left. The departure specifies a 240 degree heading; and the Flight Director's command bars remained level throughout the initial climb out. Autopilot was engaged at approximately 800 FT. and Flight Director lateral mode was observed to switch from heading to FMS. Pilot flying focused on ensuring aircraft leveled at 1;500 FT and reduced power to maintain 200 KTS. Pilot not flying focused on After Takeoff flow and frequency change to Departure. During level off; pilot flying noted FMS aircraft symbol to be approximately 1/2 to 3/4 left of CDI. Aircraft symbol on MFD appeared to passing through 260 degree course to WENTZ with Flight Director's course still showing straight ahead command and no apparent autopilot attempt to turn the aircraft. Pilot flying disconnected autopilot and aggressively banked aircraft to proceed to WENTZ; while maintaining speed and altitude. Simultaneously; pilot not flying noticed that FMS waypoint sequencing had 'Inhibited' and pressed AUTO/INHIBIT button (1R) on left CDU which resulted in Flight Director's course commanding a right turn. During the turn; Departure Control inquired if aircraft was in turn and called traffic to left descending to EWR. Pilot not flying responded that turn was in progress and traffic was in sight. Passing WENTZ a climb to 2;000 FT was commenced; which Departure subsequently changed to 6;000 FT. With aircraft back on course per flight director; autopilot was reengaged and no further anomalies noted. The Hawker 800 Aircraft Flight Manual states 'The maximum demonstrated adverse wind conditions for autopilot coupled approaches are 17 KTS crosswind component and 11 KTS tailwind component.' This has been the case since at least 2002; prior to widespread use of autopilot coupled departures. As far as I am aware; the Flight Director's logic and autopilot performance is the same whether on approach or departure. Experience has shown that the Flight Director/Autopilot is capable of maintaining course on approach in crosswinds well in excess of 17 KTS. But I think the high crosswind and drift rate was more than the system could handle. By specifying an initial heading; rather than course to fly; during the departure; it appears the aircraft drifted left to the point that the Flight Director could not; or was slow to resolve the actual position and the desired position; and apply corrections. This may account for the Flight Director going into INHIBIT mode. There is a lot going on in the first 30 sec after liftoff from TEB; with at least 3 critical navigation parameters occurring during that time. While automation can ease the workload to some extent; it has to be closely monitored (and at the expense of an outside scan).
[Narrative 2 contained no additional information.]
A HS-125-800XP departed on the TEB RUUDY 4 with a 24 KT crosswind which the autopilot apparently could not compute a track correction for; as such did not turn at WENTZ.