NTSB Factual Report

On August 12, 2011, at 1440 eastern daylight time, a Cessna U206F, N8737Q, registered to Coastal Aero LLC and operated by Key West Seaplanes, collided with trees during a forced landing in the vicinity of Arcadia, Florida. The airplane sustained structural damage to the wings, fuselage, and a post-crash fire ensued. Visual meteorological conditions prevailed and no flight plan was filed. The sightseeing flight was conducted under the provisions of 14 Code of Federal Regulations Part 91. The certificated commercial pilot sustained minor injuries and the four passengers were not injured. The flight was originating at the time of the accident.

The pilot stated that during the water takeoff he used 10 degrees of flaps to get the airplane on "plane." Once the airplane began to climb, he added another 10 degrees of flaps to climb out. He said that the airplane climbed to approximately 400 feet and would not maintain altitude. He said that the engine rpm remained high but the airplane began to descend. He initiated a forced landing into a wooded area and the airplane collided with trees. The pilot did not report any flight control anomalies prior to the accident.

The airplane came to rest in a wooded area. Trees along the crash debris line exhibited evidence of propeller slant cuts. Examination of the wreckage by a Federal Aviation Administration inspector revealed the engine assembly was separated from the firewall. The forward cabin area sustained extensive fire damage. Continuity of the flight controls was confirmed from the cabin area aft to all flight control surfaces.

The engine was recovered to an authorized repair facility for an engine examination. The engine was started and the throttle was gradually increased to full throttle. The engine produced 2,400 rpm, with manifold pressure at 29 inches, and the oil pressure was at 60 PSI. The engine throttle was reduced to near idle. The throttle was rapidly accelerated to full power twice and the engine performed without any hesitation, stumbling, or interruption in power. After approximately eight and a half minutes of run time, the engine power was reduced to near idle, and the engine idled smoothly until being shut down. There were no anomalies noted during the engine run that would have prevented normal operation. The logbooks were not recovered for review. According to the pilot, the logbooks were in the airplane at the time of the accident and were destroyed in the post crash fire.

The airplane had a certificated takeoff gross weight of 3,800 pounds, according to the Supplemental Type Certificate (STC) (SA01185CH), with an associated center of gravity between +40.0 to +47.4 inches. Utilizing the most recent weight and balance record, and the weights of the pilot and passengers, 45 gallons of fuel, engine oil, and baggage, the estimated weight of the airplane was at least 3,855 pounds with an associated center of gravity of 45.10 inches.

The pilot indicated in a statement that the maximum gross weight of the airplane was 3,800 pounds. He reported that the takeoff weight at the time of the accident was 3,695 pounds, with an associated center of gravity of 44.94 inches. The passenger and baggage weights that the pilot provided were estimated. A review of the supplement flight manual section on weight and balance warns that it is the responsibility of the pilot to ensure that the amphibian is loaded properly. Operation outside of prescribed weight and balance limitations could result in an accident and serious or fatal injury.

A review of recorded data from the Punta Gorda Airport (PGD) automated weather observation station revealed that six minutes after the accident, conditions were calm wind, visibility of 10 miles, cloud conditions few at 8,000 feet above ground level, temperature 31 degrees Celsius, dew point 19 degrees Celsius, and altimeter 29.87 inches of mercury. PGD is located about 26 miles northwest of the accident site. The density altitude at the time of the accident was approximately 2,297 feet. Review of the performance chart for an airplane with the same STC modification revealed that the airplane, in a clean configuration at a maximum gross weight of 3,800 pounds, should have been able to maintain a rate of climb of 600 feet per minute at approximately 65 knots. High density altitude and increased gross weight both adversely affect an airplane’s climb performance. The presence of either or both conditions requires pilot vigilance to maintain adequate airspeed during takeoff and climb.

A review of the Federal Aviation Administration Accident Prevention Program for Density Altitude states that even at lower elevations, aircraft performance can become marginal and it may be necessary to reduce aircraft gross weight for safe operations. Therefore, it is advisable, when performance is in question, to schedule operations during the cool hours of the day, early morning or late afternoon, when forecast temperatures are expected to rise above normal. Early morning and late evening are sometimes more ideal for both departure and arrival.

NTSB Probable Cause

The pilot’s decision to take off in high density altitude conditions with the airplane over its maximum gross weight, due to the pilot’s improper weight and balance calculations, which resulted in the airplane’s inability to climb or maintain altitude.