The US National Transportation Safety Board (NTSB) says that in 2011 there were "marked increases" in accidents involving "on-demand Part 135 operations", mostly air taxi flights.

Meanwhile, statistics for US civil aviation as a whole showed a slight increase in 2011 compared with the previous year.

This contrasts with the results from the scheduled Part 121 airlines and Part 135 commuters which, for the second successive year, suffered no fatal accidents.

The all-sector US civil aviation accidents total rose from 1,500 in 2010 to 1,550 in 2011. Fatalities also increased, from 473 in 2010 to 485 in 2011. All the fatalities were in general aviation and Part 135 on-demand operations encompassing charter, air tour, and air medical operations. Four non-fatal accidents were recorded for scheduled Part 135 commuter operations.

Total accidents involving on-demand Part 135 operations climbed from 31 in 2010 to 50 in 2011, while fatal accidents rose from six to 16 and fatalities rose from 17 to 41.

The accident rate per 100,000 flight hours for on-demand Part 135 operations rose dramatically, from one in 2010 to 1.5 in 2011.

General aviation accidents, which continue to account for the greatest number of civil aviation accidents, reversed their downward trend of the previous two years, increasing from 1,439 in 2010 to 1,466 in 2011, but fatalities declined from 454 in 2010 to 444 in 2011.

Meanwhile the number of general aviation flight hours actually increased in 2011, and the accident rate per 100,000 flight hours decreased from 6.63 in 2010 to 6.51 in 2011.

Source: Flight International