Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew FLC complied w / Automation / Advisory
Human Factors
After takeoff from ZZZ; the red lights for all three landing gear remained illuminated. Accomplished 'landing gear fails to retract' checklist; gear retracted normally; and flight continued to ZZZ1. No airspeed or altitude limits were exceeded. During 'gear fails to retract' checklist; discovered the overhead gear door was slightly open; and after closing it and finishing the checklist; the gear retracted normally. The aircraft was towed to its spot in ZZZ; so the tow team; first officer; and myself all failed to notice the door wasn't completely closed.Will put more emphasis on double checking the configuration of the aircraft after its towed.
DH8-400 flight crew reported landing gear retraction issue after takeoff.