Piper PA23-250 accident at Ohio, 10 May 1975

Accident narrative

About 0126 e.d.t. on May 10, 1975, NAVIK Air Flight 11, a Piper PA23-250, crashed 3.3 nautical miles short of the runway during a night approach to runway 5R at Cleveland-Hopkins International Airport in Ohio. The pilot was killed and his 14-year-old son, the only passenger, was seriously injured. Because of air traffic control handoff procedures and damage to the aircraft's emergency locator transmitter, the accident went unnoticed for nearly five hours.

### The flight

Flight 11 was a scheduled air taxi courier service originating in Rochester, New York, with intermediate stops in Buffalo, Pittsburgh, and Columbus. The flight departed Columbus at 0100 with about 200 pounds of cargo.

The pilot held a commercial certificate and had accumulated 6,705 flight-hours, including 862 hours in the Piper PA23-250. He flew this scheduled route five nights a week.

At 0112, Cleveland Air Route Traffic Control Center handed the flight off to Cleveland approach control. The pilot reported his altitude at 7,000 feet and stated he had the automatic terminal information service. At 0116, approach control cleared the flight to join the instrument landing system (ILS) and descend to 4,000 feet. The pilot acknowledged, reporting "out of seven for four."

At 0119, the approach controller advised the flight it was 15 miles from the outer marker, cleared it for the ILS runway 5R approach, and instructed the pilot to contact the tower inbound from the marker. After a query from the controller, the pilot affirmed the clearance at 0119:56. This was the final transmission from the aircraft.

The approach controller monitored the flight on radar until it passed the outer marker, then directed his attention to other traffic, assuming the pilot had contacted the tower. The local controller in the tower never received a call. At 0126, the local controller cleared another aircraft for takeoff, checking his radar display and scanning visually. He saw no aircraft on the approach path and was unaware Flight 11 was inbound.

The aircraft crashed into a pine tree farm 2.6 nautical miles inside the outer marker. The pilot's son, who had been asleep in the front seat, awoke outside the wreckage. At daylight, he walked to a road and received help from a passing motorist. The tower was notified of the accident at 0630.

### What the investigation found

The aircraft cut a 160-foot swath through the trees on a heading of 050 degrees. Tree cuts and propeller damage indicated both engines were developing power. The aircraft was in wings-level flight, descending at an angle of about 3 degrees. The landing gear and flaps were retracted. Investigators found no evidence of pre-impact malfunction in the engines or flight controls. Weather was clear with 15-mile visibility and was not a factor.

The emergency locator transmitter (ELT) remained in its bracket, but crash damage separated its antenna lead-in wire. With only one inch of bare wire exposed inside the metal fuselage, the ELT produced a weak signal that could not be received by the tower.

Post-mortem examination of the pilot revealed no evidence of incapacitating disease, drugs, carbon monoxide, or alcohol. Another pilot who had recently accompanied him to build flight experience told investigators the pilot became progressively more tired toward the end of his work week. He noted the pilot would occasionally doze off but awaken when he heard his call sign.

Although the aircraft's clock stopped at 1:31, the Board calculated the crash occurred at 0126, based on a continuous 600-foot-per-minute descent from 7,000 feet and the local controller's observation of a clear radar scope at 0126:56. The Board noted that the wings-level attitude, 3-degree descent angle, and a vertical speed indicator reading of 700 feet per minute down suggested the autopilot was in use and stabilizing the flightpath.

The Board believed the pilot was unaware of the aircraft's progress. Combined with a light workload and relaxed cockpit atmosphere, the evidence suggested the pilot was asleep, though the Board stated this hypothesis could not be substantiated.

The investigation also examined the air traffic control system's failure to detect the missing aircraft. The tower was using automated "Quick Look" radar handoff procedures, which required no verbal coordination between the approach and local controllers. The local controller was responsible for monitoring his radar display to identify arriving flights. The Board concluded the local controller failed to monitor the display effectively and instead relied on the pilot's radio call. However, the Board also noted that the facility's procedures at the time did not clearly define the local controller's monitoring responsibilities when using the automated handoff system.

### Probable cause

The National Transportation Safety Board determined that "the probable cause of this accident was the pilot's failure to arrest the aircraft's descent during a landing approach inbound from the outer marker under nighttime VFR conditions. The Safety Board could not determine the reasons for his failure."