Final Report: Failure to see-and-avoid cost 11 lives

 - January 28, 2008, 8:50 AM

PA-31-350 AND PA-44-180, BURLINGTON TOWNSHIP, N.J., AUG. 9, 2000– Piper Navajo Chieftain N27944, operated by Patuxent Airways of Hollywood, Md., and Piper Seminole N2225G, operated by Hortman Aviation Services of Philadelphia, were both destroyed when they collided in midair at 7:52 a.m. EST over Burlington Township. The Safety Board determined the probable causes to be failure of the pilots of both airplanes to see and avoid each other and maintain proper airspace separation during VFR flight.
The Navajo was operating as a Part 135 charter and the Seminole as a multi-engine instructional flight. The ATP-rated pilot, commercial-rated pilot and seven passengers aboard the Navajo were killed, as were the flight instructor and private pilot aboard the Seminole. VMC prevailed at the time.
The Navajo was en route from Trenton Mercer County Airport (TTN), N.J., to Naval Air Station Patuxent River, Md. TTN controllers cleared the Navajo for takeoff at 7:46 a.m. and two minutes later authorized a radio frequency change, which the crew acknowledged. No further transmissions were heard from the Navajo pilots and impact and fire damage prevented investigators from determining the radio frequencies that had been selected in the Navajo.
The Seminole at 7:45 a.m. departed Runway 24 at Northeast Philadelphia Airport (PNE), which is 14.5 nm southwest
of TTN. Shortly after takeoff, the tower controller approved a frequency change, which was acknowledged. No further transmissions were heard from the Seminole.
Radar data indicates that shortly before the collision the Seminole was on a northeast heading and the Navajo was southbound. Both were at 3,000 feet. About a minute before the collision the Seminole started a gradual left turn toward the north-northeast. The last secondary radar return before the collision was received from the Seminole at 7:52:37.68 at an altitude of 3,000 feet, less than 0.4 nm southwest of the Navajo’s last radar return. The only returns received after that in the area surrounding the collision were primary returns that began to appear a few seconds later, near the last secondary returns associated with the Navajo and Seminole. According to the NTSB, the loss of secondary returns and the appearance of a cloud of primary returns are consistent with loss of power to the transponders and the breakup of the two airplanes following the collision.
The NTSB found the flight crews of both airplanes were properly certified and qualified, there were no maintenance-
related issues and the wreckage indicated that either airplane had experienced an in-flight fire, birdstrike or structural or mechanical failure.
Tissue samples revealed that the pilot of the Seminole had taken the antihistamine doxylamine sometime before the accident, but it was impossible to determine exactly when the pilot may have ingested the medication or if it impaired his performance.
The investigator concluded that the Seminole would have been visible to the pilots in the Navajo at least 60 seconds before the collision, and the Navajo would have been visible to the Seminole pilots for most of the final 60 seconds. The investigation further revealed that about four seconds before the midair, or about 0.11 nm separation, the angular width of each airplane in each pilot’s field of vision would have been about one-quarter inch apparent size at the windshield.     o