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Copyright © 2008, Emerald Group Publishing Limited
Range of safety issues in first investigation of unmanned aircraft accident
Article Type: Safety topic and notes From: Aircraft Engineering and Aerospace Technology: An International Journal, Volume 80, Issue 2.
As a result of its first investigation of an accident involving an unmanned aircraft (UA), the National Transportation Safety Board today issued a total of 22 safety recommendations to address what NTSB Chairman Mark V. Rosenker said were “a wide range of safety issues involving the civilian use of unmanned aircraft.”
The safety recommendations approved by the Board stemmed from the 25 April 2006, accident in which a turboprop-powered Predator B operated on a surveillance mission by the US Customs and Border Protection (CPB) crashed in a sparsely populated residential area near Nogales, Arizona. No one on the ground was injured; the remotely piloted 66-foot wingspan 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 the subsequent total loss of engine power, and a lack of a flight instructor in the Ground Control Station.
At the Board meeting, the NTSB highlighted several areas of particular interest including: the design and certification of the unmanned aircraft system (UAS); pilot qualification and training; 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?”
Expressing concerns about how manned and UA will share the same airspace, Chairman Rosenker said, “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.”
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.”
On the issue of UA operations-related communications, the Safety 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. To enhance the efficacy of future investigations of UA incidents and accidents, the NTSB recommended that the FAA require all conversations, including telephone conversations between UA 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 the additional safety recommendations sent to the FAA are:
Require that established procedures for handling piloted aircraft emergencies be applied to UASs.
Require that all UA operators report to the FAA all incidents and malfunctions that affect safety; require that operators are analysing these data in an effort to improve safety; and evaluate these data to determine whether programs and procedures remain effective in mitigating safety risks.
Among the 17 safety recommendations sent to US Customs and Border Protection, the operator of the UA involved in the accident, are:
Require that pilots be trained concerning the expected performance and flight path of an UA anytime communication with the aircraft is lost.
Conduct face-to-face meetings between pilots of UA and working- level air traffic controllers to clearly define responsibilities and actions require for standard and non- standard UA operations.
Identify and correct the causes of the lockups in the pilot's control console.
Revise the US 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 as a backup pilot be readily available during the operation of a UA system.
Develop a safety plan, which ensure that hazards to the National Airspace System and persons on the ground introduced by the US 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.