NYC96LA071

The pilot received a preflight weather briefing and was advised of precautions for occasional moderated mixed and rime icing, as well as isolated severe mixed and clear icing, along the route of flight. En route, he encountered icing conditions and ice accretion on the aircraft. Manifold pressure began decreasing, and the pilot was unable to maintain altitude. Subsequently, he made a forced landing in a residential area, and the airplane struck a house and a car. The pilot stated, 'At 5000 feet, I expected to be above the freezing level, due to a temperature inversion, this was the case until I reached the Philadelphia area, I then encountered light mixed icing on the leading edges...Subsequently my manifold pressure dropped to 21 inches, and I began to lose altitude...Although I expected to receive an increase in manifold pressure on my descent, none occurred. At about 2000 feet, I felt that I could not make (a nearby airport) and declared a mayday. I was maintaining 95 knots.' Postaccident examination of the airplane included an functional check of the engine in a test cell. The engine operated rich below 1800 RPM, and takeoff power was achieved. No mechanical discrepancies were noted with the airplane.

On March 7, 1996, at 1836 eastern standard time, a Beech C24R, N6625P, made a forced landing in a residential area of Philadelphia, Pennsylvania. The airplane was destroyed, and the commercial pilot received serious injuries. Instrument meteorological conditions prevailed, and the business flight which had departed Frederick, Maryland, about 1735, was operated on an Instrument Flight Rules (IFR) flight plan under 14 CFR Part 91.

The pilot received a pre-flight weather briefing via telephone at 1604. A recording of the briefing revealed that the pilot was given flight precautions for occasional moderate mixed and rime icing, below FL 190 (19,000 feet), and isolated severe mixed and clear icing below 10,000 feet. In addition, the ceilings were reported as less and 1,000 feet along his route of flight and visibilities from one to three miles with rain, snow, and fog. The pilot then filed an IFR flight plan. The pilot reported airborne at 1735, and initially climbed to 5,000 feet.

In the NTSB Accident Report, the pilot stated:

"...At 5000 ft I expected to be above the freezeing level due to temp inversion. This was the case until I reached the PHL area. I then encountered light mixed icing on leading edges...I decided to land at PNE. Subsequently my manifold pressure dropped to 21 inches and I began to loose altitude...Although I expected to receive an increase in manifold pressure on my descent, none occured. At about 2000 feet I felt that I could not make the field and declared a MAYDAY. I was maintaining 95 kts. There were no suitable emergency landing sites...."

The airplane struck the roof of a row house, about 3.3 nautical miles from the approach end of runway 6, and then descended to the street below where it struck an unoccupied, parked vehicle.

The 1750 observation at Northeast Philadelphia Airport included a measured ceiling of 800 feet broken, visibility of 1 1/2 miles with light freezing drizzle, and fog, temperature 31 degrees Fahrenheit, and dewpoint 29 degrees Fahrenheit.

The airplane and engine were examined under the supervision of the Federal Aviation Administration (FAA) airworthiness inspector. No evidence of a mechanical failure was found. The engine was placed in a test cell and during the engine run, was found to be rich, but would still develop takeoff power.

The Pilot's Operating Handbook contained the following under the Limitations Section, "FLIGHT IN KNOWN ICING CONDITIONS IS PROHIBITED." The only ice control item on the airplane was a heated pitot (airspeed) tube.

When asked why he had flown in the weather, the pilot reported that he had received a second weather briefing just prior to departure with improving weather. A check of FAA records failed to find a record of the briefing. The pilot also reported that he had flown in similar conditions with no problems in the past.