PA-18/19 Super Cub
Flight Crew Air Transport Pilot (ATP); Flight Crew Flight Instructor
Situational Awareness; Human-Machine Interface; Confusion; Workload
Aircraft Equipment Problem Less Severe; Inflight Event / Encounter Fuel Issue
Flight Crew Returned To Departure Airport; Flight Crew Became Reoriented; Flight Crew Took Evasive Action
Aircraft; Human Factors; Procedure
While conducting glider towing operations; I was the only pilot in the tow plane with a glider in tow. During initial climb out at full power (at approximately 500 ft AGL); my airplane experienced a sudden power loss. I immediately switched fuel tanks and power was restored. However; during the period of power loss the tow plane descended relative to the glider; who therefore wisely disconnected the towline from his end and conducted a flawless return to the takeoff point. Meanwhile; with power restored but not certain why I had lost power; I climbed approximately 1;500 feet AGL over the runway (a private grass strip); from which point I conducted an idle descent and landing. After landing; I conducted a power check (magnetos) with normal results. After shutting down; I examined the aircraft's fuel quantity and discovered that the initially-selected tank (LEFT) appeared empty. The right tank contained an estimated 1.5 hours of fuel (approximately 10 gal). I had; until this point; estimated my left tank as containing at least 5 gallons of fuel and planned to switch to the right tank after the tow that was being conducted. The aircraft's fuel quantity indications are sight glasses on the inboard wing root; in the cockpit's overhead and are known to be poor; especially on uneven ground. We added fuel into the left tank; debriefed the event and continued operations without further incident.
A PA-18 towing a glider reported a loss of power after takeoff. The pilot quickly recovered by selecting the other fuel tank and upon landing discovered the initially selected fuel tank was empty.