History of Flight
On April 19, 2016, at about 2115 central daylight time, a Beech 65-A90-1 airplane, registration N7MC, collided with towers suspending high-power transmission lines while attempting to land at Slidell Municipal Airport (ASD), Slidell, Louisiana. Both pilots were fatally injured, and the airplane was destroyed. The airplane was registered to and operated by the Saint Tammany Parish Mosquito Abatement District as a 14 Code of Federal Regulations Part 91 public aircraft operations flight. Night visual meteorological conditions existed at the airport at the time, and the flight was operating on a visual flight rules flight plan. The local flight originated about 2000.
After completing a planned mosquito abatement application flight, the pilots radioed their intention to land at ASD. They were flying a visual pattern to runway 18, while another company airplane conducted a practice GPS approach to the same runway. When the other company's pilot reported crossing the final approach fix, the accident pilot stated they were on the left base leg and number one to land. Shortly thereafter, the other crew saw a blue arc of electricity followed by a plume of fire. The accident pilots could not be reached, and emergency personnel were notified. The airplane was located in a marsh about 0.6 nautical mile north-northwest of the approach end of runway 18.
Personnel Information
The left-seat pilot, aged 59, held a commercial pilot certificate with ratings for airplane single-engine land, multiengine land, and instrument airplane. He also held a flight instructor certificate for single-engine and instrument airplane. His second-class medical certificate was issued February 18, 2016, with a corrective lenses limitation. He reported using hydrochlorothiazide and irbesartan. As of December 11, 2015, he had 6,825 hours single-engine total time, 952 hours multiengine total time, and 7,762 total hours with 1,135 hours night time. His last biennial flight review was in February 2014. Company records showed he flew the accident airplane for 7.4 hours in 2015 and 5.7 hours in 2014.
The right-seat copilot, aged 68, held an airline transport pilot certificate with multiple ratings and a flight instructor certificate. His second-class medical certificate was issued July 14, 2015, with a glasses limitation. He reported using several medications including diltiazem, losartan, and warfarin. As of February 25, 2016, he had 4,310 hours single-engine, 5,910 hours multiengine, and 18,163 total hours with 4,619 hours night time. He was also the department's aerial operations supervisor and had worked for the district for 31 years.
Aircraft Information
The low-wing, twin-engine airplane was manufactured in 1968 and powered by two Pratt & Whitney Canada PT6A-20 turboprop engines driving Hartzell propellers. It was operated for mosquito abatement. The most recent inspection was a combined Phase I-IV and annual on December 1, 2015, at 15,189.6 airframe hours. The airplane had a special airworthiness certificate for restricted use (agriculture and pest control) and was equipped with a radar altimeter and dual controls.
Meteorological Information
At 2053, the ASD automated weather reported calm wind, visibility 10 miles, clear sky, temperature 68°F, dew point 64°F, and barometric pressure 30.09 inches of mercury. The moon rose at 1730 and set at 0541 with 94% illumination.
Wreckage and Impact Information
The airplane initially impacted two 70- to 80-ft-tall towers suspending high-power transmission lines. The lines ran on a heading of 150°/330° and were not required to be illuminated. Ceramic isolators were shattered on the northern pole, and the top guide wire was damaged on the southern pole. A portion of the lower chemical tank and left wing tip were found beneath the poles. The debris path followed a 175° heading for about 555 ft. The main wreckage came to rest about 0.6 nautical mile northwest of runway 18's approach end, consisting of the hopper tank frame, upper fuselage, cockpit instrumentation, inboard left wing, outboard right wing, left horizontal stabilizer, vertical stabilizer, rudder, and left engine with propeller. A post-impact fire consumed most of the cabin. Flight control continuity was confirmed; flaps were retracted. The ELT was in the armed position but thermally damaged; no beacon was heard.
Medical and Pathological Information
Autopsies conducted by the St. Tammany Parish Coroner's Office on both pilots revealed no natural diseases posing an immediate hazard to flight safety. Toxicological testing by the FAA Civil Aerospace Medical Institute detected ibuprofen and irbesartan in the left-seat pilot, and diltiazem, metoprolol, rosuvastatin, and warfarin in the copilot. Carbon monoxide (15%) was detected in the copilot's heart blood; tests for ethanol were negative.