ANC93FA060

The pilot reported that while in cruise flight looking at birds out the left side cockpit window he observed peripherally a 'white flash' fill the right side of the forward wind screen followed immediately by an audible 'thump'. The airplane began an uncontrollable descent and yaw to the right. The engine continued to run smoothly. Advancing the engine power controls had no noticeable affect on his ability to arrest the descent. The NTSB investigator in charge visited the accident site. No evidence was found of a bird strike. The accident site was surrounded by tall (white) birch trees. The pilot stated that he was not sure what he struck and that it could have been a tree.

History of flight

On May 6, 1993, at approximately 1530 Alaska daylight time, a wheel equipped Cessna 207 airplane, N70364, owned and operated by Markair Express, collided with an object while in cruise flight about 9 nautical miles north of Holy Cross, Alaska. The airline transport certificated pilot, the sole occupant on board the airplane, reported that as a result of not being able to stabilize the airplane, he performed a forced landing in a wooded area. The pilot was not injured and the airplane was destroyed. At the time of the accident, the airplane was being operated as a repositioning flight under 14 CFR Part 91. The flight departed Shageluk, Alaska, at 1518 and the destination was Aniak, Alaska. The accident site is approximately 50 nautical miles north northwest of Aniak. Visual meteorological conditions prevailed and a company VFR flight plan was filed.

The pilot offered the following information during the course of several in person interviews with the NTSB investigator in charge. He departed Shageluk with the left and right wing fuel tanks approximately half full. He initially was established in cruise flight at an indicated altitude of 500 feet msl. The propeller rpm and engine manifold pressure (mp) were set for cruise (2,300 and 23.50 inches, respectively) and the indicated airspeed was 120 knots. While looking out the left side cockpit window at birds, he observed peripherally a "white flash" fill the right side of the forward wind screen followed immediately by an audible "thump". The airplane began to descend and yaw to the right. He did not recall the rate of descent or the degree to which the plane yawed, only that the yaw did not require inordinate flight control input to overcome. While in the descent, he recalled observing an indicated airspeed of 80 knots. He was not able to discern what produced the "thump", or what damage the airplane had sustained. The engine continued to run smoothly, and all indications appeared normal. No vibration was felt either from the engine or from the flight control surfaces through the yoke. In an attempt to arrest the descent, he advanced the engine rpm and manifold pressure settings to the top of the green arc, 2500 rpm and 25 inches, respectively. Although he felt the surge in power, it did not have any noticeable affect on his ability to arrest the descent so he reduced the engine and propeller controls to their cruise setting where they remained throughout the crash landing into trees. He could not rule out the possibility that he may have struck a tree.

Witness information

There were no witnesses to the accident.

Flightcrew information

The pilot, dob 03/08/51, holds airline transport pilot certificate No. 81604850, latest issue 05/16/91, with the ratings and limitations of airplane single and multiengine land. His first class medical certificate, dated 10/01/92, contains the limitation "holder shall wear correcting lenses while exercising the privileges of his/her airman certificate". His total pilot time is 5,395 hours of which 1,470 hours were accrued in the Cessna 207 aircraft. During the previous 90 day, 30 day, and 24 hour period, he flew 139 hour, 25 hours, and 4 hours, respectively. He completed 14 CFR Part 135 ground training on 12/09/92, 4.5 hours of flight training on 12/12/92, FAR 135.293 and 135.299 competency and line checks on 12/13/92 (1.6 hours), and initial operating experience (IOE) (11.3 hours) on 12/15/93.

Pathological information

Toxicological testing on the pilot was negative for alcohol, major drugs of abuse, and prescription and over the counter medications.

Meteorological observations

Aniak SA 2256 (1456 lcl) AWOS 7,000 scattered, visibility 10 miles, temperature 54, dew point 29, wind 080 @ 3, altimeter 29.45.

Aniak SA 2356 (1556 lcl) AWOS 6,000 scattered, 8,500 scattered, visibility 10 miles, temperature 54, dew point 28, wind 320 @ 4, altimeter 29.45.

Wreckage & impact information

The NTSB investigator in charge visited the accident site. The elevation of the accident site was 61 feet. The global positioning system (GPS) coordinates of the site are 62.19.7 N x 159.49.1 W. The collision heading and descent angle were 210 degrees (magnetic) and minus 10 degrees, respectively. The accident site was in a grove of birch (white bark) trees. Several of the trees that exhibited damage from impact with the plane were estimated to be 70 plus feet in height. The right aileron was found near one of the trees, about 45 feet from the main wreckage area. All of the components which comprised the airplane were accounted for at the site. An examination of the airplane revealed no evidence of a bird strike or preimpact problems with the aerodynamic lifting surfaces, flight control surfaces, or propeller and powerplant. The propeller blades were bent rearward and exhibited curling at the tips. The left wing fuel tank contained an unknown quantity of fuel. The right wing fuel tank was ruptured. The fuel strainer bowl contained fuel and the filter was clean.

Most of the cockpit instrumentation survived the crash with no external sign of damage. The altimeter read 29.44 inches and approximately 50 feet, respectively. The manifold pressure gauge read 30 inches. The fuel selector was in the "OFF" position.