Large Transport
Flight Crew Air Transport Pilot (ATP)
Flight Crew Total 5020
Confusion; Situational Awareness
Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural FAR; Inflight Event / Encounter CFTT / CFIT
Air Traffic Control Provided Assistance; Flight Crew Returned To Clearance
Human Factors
We were initially assigned the JCOBY 3 departure out of IAD. When cleared for takeoff from runway 30 we were assigned heading 320. At 400 ft I turned to heading 320. In the turn we had GPWS 'too low terrain'. I went TOGA and we climbed out with no other terrain indications. Being distracted by this I went off course of the departure and ATC asked if we were on the departure. We replied we were correcting to it. At altitude I reviewed the departure and saw that instructions are to climb to 820 ft before turning. Once ATC gave me the heading on takeoff I mentally did away with the departure and this was my error.
Air Carrier Captain reported receiving a GPWS alert during departure after turning too early.