Skywagon 185
Air Traffic Control Fully Certified
Communication Breakdown; Situational Awareness
ATC Issue All Types; Deviation / Discrepancy - Procedural FAR; Ground Incursion Runway
General None Reported / Taken
Procedure; Human Factors
I was training a CPCIT on Local with Lake Hood combined. The Cessna called and said that he hadn't started yet; and he had the Lake Hood ATIS and he was requesting to taxi via the slow canal for a west departure. I didn't hear the pilot say his position. My trainee advised the pilot to 'advise ready west'. The pilot acknowledged. A Taylorcraft called and my trainee cleared the Taylorcraft to land on the west water lane. We didn't see the Cessna; so we assumed that he was still starting his engines in one of the canals. My trainee attempted to reach the Cessna several times with no response. Then we observed an aircraft enter the west water lane. The Taylorcraft had already landed in the west water lane and was sliding out when the Cessna entered the water lane. The Taylorcraft had the Cessna in sight and was able to stop. My trainee never told the Cessna to cross the east/west water lane. The pilot did not acknowledge subsequent calls several minutes after initial contact. The pilot did not respond to other calls and only contacted us when he was ready to depart several minutes later. Recommendation; this is the start of the float plane season. I believe that this was an unfamiliar pilot. I missed hearing the initial position call and I had every reason to believe that the aircraft was in one of the fingers; starting his engines and was going to taxi via the slow canal for a west. The Taylorcraft had already landed when the aircraft floated into the water lane. Due to the flight characteristics of float planes; I didn't see that these two aircraft would ever hit each other. I realize that I needed to verify the aircraft's position; but since my trainee never told the pilot to cross a water lane; I assumed that he wouldn't enter a water lane.
ANC Controller providing OJT described an unsafe event when traffic utilizing the water lanes was not positively separated.