Skywagon 185
Flight Crew Multiengine; Flight Crew Commercial; Flight Crew Instrument; Flight Crew Sea
Flight Crew Last 90 Days 35; Flight Crew Total 5000; Flight Crew Type 1000
Situational Awareness; Communication Breakdown; Confusion
Airspace Violation All Types; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance; Ground Incursion Runway
Air Traffic Control Issued New Clearance; Air Traffic Control Provided Assistance; Flight Crew Requested ATC Assistance / Clarification
Airport; Human Factors
I flew into ZZZ for the first time in three years. I reviewed the departures for departure details to refresh myself. I got the ATIS information and then called ZZZ Tower. The west waterway was primarily being used for takeoff and landing. I was parked at the northwest corner of ZZZ water. I asked Tower if they were allowing takeoffs to the east; and he responded that they were too busy to do that. He gave me clearance to taxi to the east for a west takeoff. When I started to taxi to the slow taxi channel (north); the Tower asked if I was prepared to make a 'step turn to the east' I responded that I could and he told me to let him know when I was ready and I could do so after the next departing traffic. I let him know that I could and he told me to make a step turn to the east. I got on step; went down lake and took off towards the east. Tower contacted me and asked what my altitude was as I continued east and I responded 700 ft. and continued to climb to the 900 ft. ceiling published in the departure procedure.He asked me to report [the] overpass; which I did and shortly after he cleared me to turn south. He asked me when I would be able to write down a phone number to call ZZZ Tower when I landed; and I responded to the affirmative when I got a pen. I called Tower after I landed and found out that I had not been cleared to take off to the east; but had been cleared to do a high speed step taxi to the east for a westerly takeoff. It was my error. Having just asked Tower if I could get a takeoff to the east; I had thought the situation had changed and misunderstood the high speed taxi instructions to be an approval to takeoff. After talking to ZZZ Tower on the land phone after landing; realized that I had not heard the words 'cleared for takeoff'. After 54 years of flying without an incident; I put myself and potentially other pilots at risk by taking off into landing traffic. A lesson I'll never forget. My apologies to the Tower Operator that had to deal with my error.
A pilot reported taking off without a takeoff clearance from the Tower.