Flight Crew Air Transport Pilot (ATP)
Situational Awareness
Conflict Airborne Conflict; Deviation / Discrepancy - Procedural Clearance; Ground Incursion Runway
Human Factors
My first IFR departure from the Front Range airport. FTG was doing IFR departures from Runway 8. As noted in the ATIS. I called tower and requested air taxi to the A6 taxiway for a mid-field departure. I directed [the Pilot Flying (PF)] to land the aircraft on the A6 taxiway into the wind which was strong out of the East. Which is why I wanted the midfield departure as I wanted to avoid a downwind air taxi to the approach end of Runway 8. My mind set was a runway departure. But the tower was expecting a departure from the taxiway as most all of our aircraft depart in that manner. When we were cleared for takeoff I directed PF to turn towards the runway as he was beginning a departure from over the grass between the runway and the taxiway. He did a clearing pedal turn (good for him) towards the runway and I looked over my left shoulder to see a Cessna directly overhead on a departure from the runway. I announced stop over the intercom and we did. We then heard the tower calling traffic to the departing Cessna that a helicopter was departing the Alpha taxiway. Then we both realized that our take off clearance was from the taxiway not the runway. We are not sure if we crossed the hold line but that is a possibility. The rest of the flight was uneventful.We both should have listened more intently to the tower communications and not assume the clearance was for the runway. Also during our briefing we discussed that if ever one of us is confused about anything that pilot should let the other pilot know about it. We were both confused. Had we admitted that earlier the potential runway incursion might not have happened.One last thing. We both were very intent on clearing before entering the runway. PF did the clearing turn and I looked. There for we shall continue to do those things we learned in flight school.
[Report narrative contained no additional information.]
Helicopter flight crew reported a takeoff from a taxiway that may have drifted towards the runway being used by a fixed wing aircraft.