Regional Jet 900 (CRJ900)
Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 170; Flight Crew Total 22500; Flight Crew Type 15000
Situational Awareness
Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Wake Vortex Encounter
Flight Crew Became Reoriented; Flight Crew Returned To Clearance
Environment - Non Weather Related; Human Factors
At 1000 AGL on takeoff from ATL on the MUNSN SID from RWY 27R; I called for the autopilot to be selected on by my FO. We encountered mild wake turbulence from the departing B757 in front of us simultaneously with my 'autopilot' call. The FO selected the autopilot but apparently did not depress the button hard enough and the A/P failed to engage. I thought that it had so I took my hands off the controls. I had placed the aircraft in a slight left turn and it continued to turn slightly past the departure course. Once I noticed the minor deviation; I immediately corrected back to the departure course and reintercepted. I then called for the A/P and the FO engaged it and verified it was on. No other deviation of outbound track occurred after that and we continued with the departure.
CRJ900 Captain reported a track deviation resulted when the autopilot was not engaged as the reporter thought it was. A mild wake turbulence encounter was cited as contributing.