Commercial Fixed Wing
Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine; Flight Crew Instrument
Flight Crew Last 90 Days 120; Flight Crew Total 18000; Flight Crew Type 120
Other / Unknown; Situational Awareness
Ground Excursion Taxiway
General None Reported / Taken
Environment - Non Weather Related; Airport; Human Factors
During initial taxi out and under the direction of the marshaller our right main landing gear departed the paved surface and became stuck in the grass. The airport diagram does not accurately depict the taxiway layout and I did not realize how close the landing gear was to the edge of the pavement after push back. It was very dark and perhaps the marshaller could not see that either. I followed marshaling signals up until the event took place.
During initial taxi after push back; we were being directed by marshaller and our right main departed the paved surface and was stuck in the grass. I believe the cause of the event was being pushed back to close to the edge of the taxiway; very dark ramp and the airport diagram doesn't accurately depict layout. I could not see how close to the edge of the taxiway we were and possibly the ground crew either. In the future; I will be more vigilant to dark areas and better lighting on the ramp will assist.
Pilots reported during push-back from the gate the aircraft left the pavement.