B737-800
Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine; Flight Crew Instrument
Confusion; Training / Qualification; Human-Machine Interface; Situational Awareness
Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Air Traffic Control Issued New Clearance; Air Traffic Control Provided Assistance; Flight Crew Became Reoriented; Flight Crew Returned To Clearance
Chart Or Publication; Human Factors; Procedure
We were departing. After takeoff at 400 ft. we executed direct to a fix and selected LNAV. At 1;000 ft.; we set flaps up maneuver speed and climb thrust. At this time the First Officer stated Autopilot B on. We were given 3;000 ft. as our clearance altitude. I was busy swapping over to Departure and not looking up. As we were climbing through 2;100 ft.; I heard bank angle. I looked up and noticed a 40-degree bank and Autopilot B not engaged. I quickly took the airplane and noticed we were on a roughly 220 heading instead of roughly 150 heading to the fix. Departure gave us a climb and asked if we were direct to the fix. We quickly recovered and loaded direct without further incident. This event was caused by over saturation and lack of system knowledge. We can learn to have better FMA awareness. As Pilot Monitoring; I should keep my head up more; and monitor what the Pilot Flying is doing.
B737 Captain reported that an autopilot failed to properly engage and resulted in a course deviation.