A300
Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 57; Flight Crew Total 15000; Flight Crew Type 3000
Human-Machine Interface; Situational Awareness
Aircraft Equipment Problem Less Severe; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Air Traffic Control Issued Advisory / Alert
Aircraft; Human Factors
Departing ATL Runway 26L on CADIT 7 Departure RNAV to MPASS. We turned the autopilot on at 1;000 FT with Profile and NAV selected and began the slat retraction 10 knots after reaching 's' speed. After the turn to 300 degrees RNAV to MPASS; ATC told us to delete the 250 KTS speed restriction at ZELAN. After deleting the speed the aircraft automation turned the aircraft inside of MPASS. ATC advised us that 'In the future deleting the speed restriction at ZELAN does not mean go direct to ZELAN.' We indicated that the automation was flying the departure and we showed us .1 mile left of course. He indicated we were well Right of course.  The FMC logic apparently does not understand flying over a point after deleting a speed. We would recommend not deleting a speed until passing MPASS. A contributing factor may have been changing the clean-up altitude to 1;500 FT instead of leaving it at 3;000 FT. At 1;500 FT we are closer to the airport and get to S+10 much sooner.
A300 Captain on the CADIT 7 Departure from ATL is told to delete the speed restriction at ZELAN which is accomplished in the FMCG. This results in a turn direct ZELAN bypassing MPASS and an ATC admonishment.