The agency says lack of equipment and human error were to blame.
The National Transportation Safety Board has released its report on the fatal mid-air collision which occurred over Frederick in October, 2014. The agency says failure of pilots in the air to maintain visual contact with each other and the lack of radar equipment at the Frederick Municipal Airport control tower are two of the causes of the accident.
The collision occurred when the airplane “flew through the accident helicopter’s rotor system at the approximate point where the helicopter would have turned left from the crosswind to the downwind leg,” says the NTSB report. “Because of a specific advisory transmitted on the tower radio frequency advising the traffic on the downwind, the pilot of each accident aircraft was or should have been aware of each other,” the report continues.
The collision killed all three occupants on board the helicopter. The two on the plane survived.
The report also says the controller was doing all of the sequencing of aircraft in the air visually because the control tower was not equipped with radar. “This would have been especially difficult at the accident airport due to the local terrain and tree lines that extend above the pattern altitudes tower controller’s view, which can cause the aircraft to blend in with the background,” the report continues.
“It is likely that the lack of radar equipment in the tower and the controller inadequate task management also significantly reduced the potential for positive traffic conflict resolution,” the NTSB says.
At the time of the collision, the controller was not only handling the two “accident aircraft,” but also “two helicopters in the traffic pattern, one airplane conducting practice instrument approaches to a runway assigned to the accident aircraft, another airplane inbound form the southeast, and a business jet with its instrument flight rules (IFR) clearance on board,” says the NTSB report.
The agency says the collision occurred at an altitude of 1,100 feet above mean sea level. The airplane pilot was conducting a cross-country flight and was coming in for a landing, while the helicopter’s pilot and flight instructor were conducting a “local instrumental flight,” according to the NTSB report.