NTSB Cites Wide Range of Safety Issues in Unmanned Aircraft Accident

The U.S. National Transportation Safety Board (NTSB) issued 22 safety recommendations, following its first investigation of an accident involving an unmanned aircraft (UA), to address what Chairman Mark V. Rosenker described as "a wide range of safety issues."

The recommendations stemmed from an April 25, 2006, accident in which a turboprop-powered Predator B, operated on a surveillance mission by the United States Customs and Border Protection (CPB), crashed in a sparsely populated residential area near Nogales, Arizona.  While no one on the ground was injured, the remotely piloted aircraft was substantially damaged.

The Safety Board determined that the probable cause of the accident was the pilot's failure to use checklist procedures when switching operational control from a console that had become inoperable due to a "lockup" condition, which resulted in the fuel valve inadvertently being shut off and a subsequent total loss of engine power.  The lack of a flight instructor in the ground control station was also cited as a cause.

The Board highlighted several areas of interest including the design and certification of these aircraft; the training and qualification of their pilots; the integration of UAs into the air traffic management system; and audio records of all UA operations-related communications.

"This investigation has raised questions about the different standards for manned and unmanned aircraft and the safety implications of this discrepancy," said Rosenker. "Why, for example, were numerous unresolved lock-ups of the pilot's control console even possible while such conditions would never be tolerated in the cockpit of a manned aircraft?"

"The fact that we approved 22 safety recommendations based on our investigation of a single accident is an indication of the scope of the safety issues these unmanned aircraft are bringing into the National Airspace System," Mr. Rosenker said.

The Safety Board's investigation also revealed that the pilot was not proficient in the performance of emergency procedures, which led to the accident. "The pilot is still the pilot, whether he is at a remote console or on the flight deck," said Rosenker. "We need to make sure that the system by which pilots are trained and readied for flight is rigorous and thorough. With the potential for thousands of these unmanned aircraft in use years from now, the standards for pilot training need to be set high to ensure that those on the ground and other users of the airspace are not put in jeopardy."

The Board noted that there is no equivalent of a cockpit voice recorder at the pilot's control console and that the pilot's communications with air traffic controllers and others were not recorded.  It recommended that the FAA require all conversations, including telephone conversations between unmanned aircraft pilots and air traffic control, other UA pilots, and other assets that provide operational support to unmanned system aircraft system operations, be recorded and retained.

Among other recommendations, the Board suggested the FAA require unmanned aircraft system operators to:

• Establish procedures for handling piloted aircraft emergencies.

• Report to the FAA all incidents and malfunctions that affect safety; analyze these data in an effort to improve safety; and evaluate these data to determine whether their programs and procedures are effectively mitigating safety risks.

Among its 17 safety recommendations to U.S. Customs and Border Protection, the operator of the unmanned aircraft involved in the accident, the Board suggested it:

• Require that pilots be trained concerning the expected performance and flight path of an unmanned aircraft anytime communication with the aircraft is lost.

• Conduct face-to-face meetings between pilots of unmanned aircraft and working-level air traffic controllers to clearly define responsibilities and actions required for standard and nonstandard UA operations.

• Identify and correct the causes of the lockups in the pilot's control console.

• Revise the U.S. Customs and Border Protection's pilot training program to ensure pilot proficiency in executing emergency procedures.

• Require that a backup pilot or another person who can provide an equivalent level of safety be readily available during the operation of a UA system.

• Develop a safety plan, which would ensure that hazards to the National Airspace System and persons on the ground introduced by the U.S. Customs and Border Protection UA system operation are identified and that necessary actions are taken to mitigate the corresponding safety risks to the public over the life of the program.

The complete accident report can be accessed at the NTSB Website.

A synopsis of the Board's report, including the probable cause and recommendations, is available at, www.ntsb.gov, under Board Meetings. The Board's full report will be available in several weeks.  10-22-2007.

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