Narrative:

We were performing full stops taxi-back [after] we landed on runway 28L and cleared the runway. While taxiing we heard the controller clearing another aircraft (I think was a prop multi engine; I am not sure about the call sign) for takeoff; we saw that the plane was not lining up with the runway; then realized that it was actually accelerating on the taxiway. I took control of the aircraft and cleared the taxiway on the grass to avoid a possible collision (around 10 feet proximity). As soon as the plane took off I contacted the tower telling them what happened. They called that pilot informing him of the possible pilot deviations and gave him a phone number to call. After around 15 minutes the controller that was working in the tower called us asking me to call him and explaining what I saw and what happened.

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Original NASA ASRS Text

Title: General aviation flight instructor reported observing another aircraft takeoff from the occupied taxiway.

Narrative: We were performing full stops taxi-back [after] we landed on runway 28L and cleared the runway. While taxiing we heard the controller clearing another aircraft (I think was a prop multi engine; I am not sure about the call sign) for takeoff; we saw that the plane was not lining up with the runway; then realized that it was actually accelerating on the taxiway. I took control of the aircraft and cleared the taxiway on the grass to avoid a possible collision (around 10 feet proximity). As soon as the plane took off I contacted the tower telling them what happened. They called that pilot informing him of the possible pilot deviations and gave him a phone number to call. After around 15 minutes the controller that was working in the tower called us asking me to call him and explaining what I saw and what happened.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.