Event Summary
A training flight experienced an aborted takeoff that resulted in a runway excursion. The aircraft began its takeoff roll but accelerated slower than expected. After approximately 1,800 feet of roll, the student pilot rotated the aircraft to a normal climb attitude. The aircraft climbed about 5 to 10 feet before the certified flight instructor (CFI) observed that the airspeed indicator had dropped to about 40 knots. The aircraft then began to descend.
Pilot Actions
The CFI took control of the aircraft and aborted the takeoff. At that point, approximately 700 to 800 feet of runway remained. The CFI applied brakes, but the aircraft skidded off the right side of the runway at the departure end. The aircraft subsequently struck a concrete pad that housed runway end/threshold lights.
Environmental Conditions
The ambient temperature was 90 degrees Fahrenheit. The density altitude was approximately 2,250 feet. The CFI had anticipated a longer than normal takeoff roll due to these conditions. However, he was initially unable to understand why the indicated airspeed had dropped after rotation.
Aircraft Equipment
According to a report, the owner had installed a movable cover on the pitot tube to prevent insects from entering. This cover could potentially block the pitot tube opening during high angle of attack operations.