Accident Details
On September 4, 2013, at approximately 0758 mountain daylight time, a Cessna T207 airplane, registration N211AS, experienced a loss of climb performance shortly after takeoff from runway 35L at Colorado Springs Municipal Airport (COS), Colorado Springs, Colorado. The pilot executed a forced landing into a field, resulting in substantial damage to the wings and tail. The pilot and passenger received minor injuries.
The aircraft was operated by Sanborn Map Company under 14 CFR Part 91 as an aerial observation flight. Visual meteorological conditions prevailed, and the flight was operating on an instrument flight rules flight plan. The intended destination was Lubbock Preston Smith International Airport (LBB), Lubbock, Texas.
Pilot Report
The pilot reported that the engine start, taxi, and pre-takeoff run-up were normal. During takeoff, the flaps were up, boost pump off, cowl flaps open, gas on, and mixture full rich. The throttle was advanced, and engine instruments were checked; manifold pressure and propeller speed were at maximum, and other instruments were within normal parameters. The airplane lifted off at about 65–70 mph.
After climbing a couple of hundred feet, the pilot lowered the nose to accelerate to normal climb speed (90–100 mph), but the airplane stopped climbing and would not accelerate past 80 mph. Despite full power, the airplane decelerated to 70 mph while attempting to maintain altitude. With insufficient runway remaining, the pilot made a shallow right turn toward lower terrain and elected to land in a field. He noted that even in a descent with full power, he could not maintain airspeed above 65–75 mph.
Weather and Performance Factors
The reported weather at 0754 was: wind calm, visibility 10 statute miles, broken ceiling at 17,000 feet above ground level, temperature 21°C, dew point 12°C, and altimeter setting 30.30 inches of mercury. The density altitude was calculated to be about 8,000 feet above mean sea level.
The airplane was a 1974 Cessna T207, powered by a turbo-normalized Continental TSIO-520-G engine rated at 300 horsepower. The pilot listed the airplane's weight at 3,790 pounds, with a maximum gross weight of 3,800 pounds.
Using a Koch Chart and the pilot's information, the takeoff ground run distance would have increased to about 2,640 feet, the distance to clear a 50-foot obstacle to about 4,728 feet, and the maximum rate of climb would have decreased to about 300 feet per minute. These performance calculations were based on the use of 10 degrees of flaps for takeoff.
Relevant Guidance
The Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25A) discusses operations in the "region of reversed command." It states that if during a soft-field takeoff and climb the pilot attempts to climb out of ground effect without first attaining normal climb pitch attitude and airspeed, the airplane may inadvertently enter the region of reversed command at a dangerously low altitude. Even with full power, the airplane may be incapable of climbing or maintaining altitude. Lowering the pitch attitude to increase airspeed will inevitably result in a loss of altitude.