Narrative:

Flight crew briefed and understood the RUUDY4 departure from teb prior to takeoff; including engagement of the autopilot before the first level-off (wentz). Departure was properly loaded in FMS. After takeoff; at approximately 500 ft MSL; the FMS automatically switched from heading mode to LNAV mode; as the crew had briefed and expected.in capturing the LNAV mode; somewhere between 1.3 and 2.3 miles on the departure; the flight director commanded an initial turn to [toward] the 260 heading [track] before correcting back to the 240 heading. During this time; the pilot flying followed the command bars; turning to the 260 heading before the charted intercept from the 240 heading. ATC queried if the aircraft was on the departure and said it looked like we had turned too early. At this point the pilot flying returned to a 240 heading to rejoin the departure.while I responded to the radio call I also noted that the pilot flying had climbed to an altitude of 1;600 ft MSL and made the statement 'altitude.' the pilot flying corrected to 1;500 MSL. The altitude situation could have been avoided by engagement of the autopilot at 1;000 ft; as briefed prior to takeoff. The aircraft avionics did try to make an abrupt capture and would have caused the airplane to turn off course even if the autopilot had been engaged. Better situational awareness on the part of flight crew would have lead the pilot flying to follow the departure procedure as depicted on the chart rather than relying solely on the command bars.

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Original NASA ASRS Text

Title: A momentary erroneous right turn command as the FMS transitioned from heading to LNAV mode while flying the RUUDY RNAV SID from TEB resulted in a premature turn to intercept the track to WENTZ. That distraction contributed to a small altitude deviation when the pilot flying failed to level at 1;500 FT MSL as charted.

Narrative: Flight crew briefed and understood the RUUDY4 departure from TEB prior to takeoff; including engagement of the autopilot before the first level-off (WENTZ). Departure was properly loaded in FMS. After takeoff; at approximately 500 FT MSL; the FMS automatically switched from HDG mode to LNAV mode; as the crew had briefed and expected.In capturing the LNAV mode; somewhere between 1.3 and 2.3 miles on the departure; the flight director commanded an initial turn to [toward] the 260 heading [track] before correcting back to the 240 heading. During this time; the pilot flying followed the command bars; turning to the 260 heading before the charted intercept from the 240 heading. ATC queried if the aircraft was on the departure and said it looked like we had turned too early. At this point the pilot flying returned to a 240 heading to rejoin the departure.While I responded to the radio call I also noted that the pilot flying had climbed to an altitude of 1;600 FT MSL and made the statement 'altitude.' The pilot flying corrected to 1;500 MSL. The altitude situation could have been avoided by engagement of the autopilot at 1;000 FT; as briefed prior to takeoff. The aircraft avionics did try to make an abrupt capture and would have caused the airplane to turn off course even if the autopilot had been engaged. Better situational awareness on the part of flight crew would have lead the pilot flying to follow the departure procedure as depicted on the chart rather than relying solely on the command bars.

Data retrieved from NASA's ASRS site as of July 2013 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.