Narrative:

Myself; and a student departed on a private pilot training lesson in a cessna 162 skycatcher. Prior to takeoff; we had completed our run-up and had verified the door latches (primary and secondary) on both student's and my side of the aircraft were latched; and configured the aircraft for departure. Upon reaching 2;600 feet MSL; we turned northwest. After reaching 4;000 feet MSL; I instructed my student to level off and maintain altitude to avoid the overlaying airspace. Over [a lake]; we heard a loud pop followed by extreme wind noise. I immediately took over control of the aircraft and identified the door was open. I asked the student to pull the door closed; which he informed me was missing.upon a quick look over; unable to see the rest of the door structure due to the way it was folded; I determined the door had completely detached itself. I informed tower of the situation and advised them it had fallen below to the lake area. They cleared me for immediate landing back. I chose not to deploy flaps and maintained minimal pressure on the elevators since I was unsure if the door had contacted any of these surfaces upon its assumed departure from the aircraft. After landing; I noted the door was still attached to the airframe and that I had been unable to see it due to the way the airstream had held it against the fuselage in flight.

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Original NASA ASRS Text

Title: C162 flight instructor reported the left door opened in flight.

Narrative: Myself; and a student departed on a Private Pilot training lesson in a Cessna 162 Skycatcher. Prior to takeoff; we had completed our run-up and had verified the door latches (primary and secondary) on both student's and my side of the aircraft were latched; and configured the aircraft for departure. Upon reaching 2;600 feet MSL; we turned Northwest. After reaching 4;000 feet MSL; I instructed my student to level off and maintain altitude to avoid the overlaying Airspace. Over [a lake]; we heard a loud pop followed by extreme wind noise. I immediately took over control of the aircraft and identified the door was open. I asked the student to pull the door closed; which he informed me was missing.Upon a quick look over; unable to see the rest of the door structure due to the way it was folded; I determined the door had completely detached itself. I informed tower of the situation and advised them it had fallen below to the lake area. They cleared me for immediate landing back. I chose not to deploy flaps and maintained minimal pressure on the elevators since I was unsure if the door had contacted any of these surfaces upon its assumed departure from the aircraft. After landing; I noted the door was still attached to the airframe and that I had been unable to see it due to the way the airstream had held it against the fuselage in flight.

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.