Perhaps as an example of the NTSB moving forward on long-outstanding issues, it has asked the FAA to require nonscheduled Part 135 operators to report activity data annually, including flight hours, revenue miles, aircraft types and missions.
The Board said that as early as 1972, it published its concerns regarding the adequacy of FAA data generated for nonscheduled Part 135 operations. In its Air Taxi Safety Study, the Board recommended that the FAA redraft Part 135 to recognize that commuter airline operations and air-taxi charters are separate entities.
Although the FARs were eventually changed to recognize the differences between commuters and air taxis, nonscheduled Part 135 operators (air taxis) have never been required to report activity. The NTSB said that valid activity data are necessary to compare the incident and accident rates for different aircraft types and types of operations, and to assess the effect of regulatory initiatives.
In 1993 the Safety Board again suggested that on-demand operators be required to report revenue flight-hour activity, at least annually. The FAA’s response acknowledged that, although estimates of on-demand air-taxi activity were of marginal quality, resources to complete an additional survey each year were not available.
Other segments of commercial aviation–Part 121 scheduled and nonscheduled air carrier operations and scheduled Part 135 operations– are required to regularly report revenue flight activity to the Transportation Department. “Unlike all Part 121 air carriers and scheduled Part 135 carriers, nonscheduled Part 135 operators are not currently required to report flight activity for their revenue flights,” the Safety Board said, even though it could be the largest of the four commercial segments and accounts for 50 to 60 percent of all commercial aviation accidents each year.
To determine flight activity for this group of operations, the FAA uses the General Aviation and Air Taxi Activity (GAATA) survey, conducted by its Office of Aviation Policy. The GAATA survey was designed in 1978 to gather information from owners of GA and air-taxi operators regarding flight hours, avionics, base location and primary use.
To conduct the survey, the FAA sends questionnaires to aircraft owners selected from its Civil Aviation Registry using a procedure based on aircraft type and geographic regions. For the 2001 survey, questionnaires were sent to the registered owners of 30,886 aircraft, and completed forms were returned for a little more than half of those.
Aircraft used in on-demand charter operations accounted for only 1.9 percent of the fleet targeted by the survey, although estimates of fleet size for nonscheduled Part 135 operations vary from 4,000 to more than 11,000. As a result of this imprecise activity estimate, the Safety Board expressed concern that accident-rate calculations are not accurate enough to evaluate safety actions effectively.