Dash 8-400
Flight Crew Air Transport Pilot (ATP)
Confusion; Situational Awareness
Deviation / Discrepancy - Procedural Published Material / Policy
General None Reported / Taken
Company Policy; Procedure; Chart Or Publication
It was one of the first deicing events of the year. The station wanted to tow the plane over to the deice pad.  While being towed; we started the engines; and deiced without incident. After the deice was complete; we realized that the APU had been left on the entire time.  They sprayed in place/towed to pad deice checklist does not direct the crew to run an after start checklist; or to ensure the APU is off prior to deicing--there is a note at the end of the checklist that directs us to ensure the APU isn't on during the deicing process.The deice checklist should be rewritten to include a 'deicing configuration' that is consistent among types of deicing used.  And there should be a specific note about the APU being off prior to the deice; or preferably a checklist item to turn it off.
DH-8-400 Captain reported having the APU on while being deiced when it should have been off. The checklist layout is cited as contributing to the mistake.