Q400
Flight Crew Air Transport Pilot (ATP)
Communication Breakdown; Confusion; Troubleshooting; Human-Machine Interface
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Returned To Departure Airport; General Declared Emergency
Human Factors; Aircraft
After takeoff; positive rate was called and the gear handle was selected to the up position.  All 3 landing gear did not begin to retract.  All 3 gear position lights turned red and the gear handle light stayed amber.  Tower cleared us to a heading of 140 and contact departure. After contacting departure control we advised that we were experiencing a landing gear malfunction and that we would need radar vectors to stay in the area to conduct some checklists.  Departure tuned us to a heading of 340 and cleared us to climb to 6000 MSL. The Landing Gear Failed to Retract [checklist] was called for. This first item on the checklist says 'Gear Pins...Verify 2 and Dark.' It was verified that both main gear pins were in the holder behind the captains seat and that the nose gear pin lock indicator light was dark. The 'pilot flying' responded 'YES' the 'pilot not flying' then moved to the next BOLD line item  on the checklist. It read 'Landing Gear Selector...DOWN.  The 'pilot flying' challenged the item read with the response 'REALLY'? The 'pilot not flying' re-read the same line item a second time. The  'pilot flying' then said 'gear handle down'. The gear handle was then moved to the down position. All 3 gear indicator light turned green and the amber gear handle light went out.  The next BOLD line item said 'LAND AS SOON AS PRACTICAL'. At this time a clearance back was requested and the emergency equipment was requested.  All the remaining normal (Decent; Approach and Landing) checklist were conducted.  At one point during this phase of flight the 'pilot flying' requested that the standby gear indicator lights in the cockpit floor be checked for 3 GREEN indications.  It was confirmed that all 3 gear indicators were GREEN.  The flight proceed at this point with a normal approach and landing.         It wasn't until the filling of an Irregularity report that it was discovered that the 'pilot not flying' had not followed the correct response arrow for the first line item read.  A 'YES' response arrow lead to checking more items in the cockpit and then ultimately lead to an 'Alternate Gear Extinction'.
When all three landing gear failed to retract after takeoff the flight crew of a Q400 aircraft conducted a flawed checklist; got three green lights nonetheless; declared an emergency and returned uneventfully to their departure airport.