B737 captain reported that an autopilot failed to properly engage and resulted in a course deviation...

Attributes
ACN	1714144
Time
Date	201911
Local Time Of Day	1801-2400
Place
Locale Reference	RFD.TRACON
State Reference	IL
Environment
Light	Night
Aircraft 1
Make Model Name	B737-800
Operating Under FAR Part	Part 121
Flight Phase	Climb
Route In Use	Direct
Flight Plan	IFR
Person 1
Function	Captain Pilot Not Flying
Qualification	Flight Crew Air Transport Pilot (ATP) Flight Crew Multiengine Flight Crew Instrument
Events
Anomaly	Deviation - Procedural Clearance Deviation - Procedural Published Material / Policy Deviation - Track / Heading All Types

Narrative:

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.

Original NASA ASRS Text

Title: B737 Captain reported that an autopilot failed to properly engage and resulted in a course deviation.

Narrative: 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.

Data retrieved from NASA's ASRS site 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.