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Improve the Safety of Part 135 Aircraft Flight Operations
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 Improve the Safety of Part 135 Aircraft Flight Operations

Improve the Safety of Part 135 Aircraft Flight Operations header graphic.

What is the problem?

Regardless of the purpose of the flight or the type of aircraft, all flights should be safe—right now they may not be. That’s because the Federal Aviation Administration (FAA) doesn’t require air medical service, air taxi, charter, or on-demand flights to meet the same safety requirements as commercial airlines. Even without requirements, many such operators could be taking more initiative to ensure the highest level of safety for their aircraft and passengers.

Most of the organizations that conduct Part 135 operations do not have—and are not required to have—a safety management system (SMS), flight data monitoring (FDM), or controlled flight into terrain (CFIT)-avoidance training program. These programs enable operators to take a strategic approach to safety management, requiring that safety-focused policies, practices, and procedures be implemented to keep aircrews and passengers safe. SMS and FDM programs also yield data that can be used to improve safety practices to better prevent accidents. We don’t know how many operators have SMS or FDM programs because the FAA doesn’t require operators to implement and report on them.

CFIT-avoidance training programs are required for Part 135 helicopter operations, but not for Part 135 fixed-wing operations. We have investigated several fatal CFIT accidents involving flights operated under visual flight rules at low altitudes where terrain awareness and warning system (TAWS) alerts were inhibited due to the lack of effective TAWS protections and nuisance-alert mitigations.

Despite the availability of SMS, FDM, and CFIT-avoidance programs, Continued on next page Improve the Safety of Part 135 Aircraft Flight Operations preventable crashes involving Part 135 aircraft are occurring all too frequently, like the November 10, 2015, fatal accident in Akron, Ohio, involving a British Aerospace HS 125-700A. Our investigation identified a lack of compliance with standard operating procedures that could have been mitigated with an SMS.

Our investigation of the October 2, 2016, crash of a turbine-powered Cessna 208B Grand Caravan airplane into steep, mountainous terrain northwest of Togiak, Alaska, identified safety issues related to a lack of SMS, FDM, and adequate CFIT training and technology use. In this accident, which killed two pilots and the passenger, we discovered the need for improvements in the operator’s CFIT-avoidance training, and the need for SMS and FDM programs (and supporting devices) for Part 135 operators, among other issues.

What can be done?

We know that SMS, FDM, and CFIT programs can improve safety and prevent crashes. We currently have 21 open safety recommendations addressing the safety gap in Part 135 operations. Operators must be proactive about safety; they should not wait for regulations or an accident to move them to action. Some operators have already incorporated SMS, FDM, and CFIT programs and are seeing tremendous safety returns.

To increase use of SMS, FDM, and CFIT programs in Part 135 aircraft, the following actions should be taken:


  • Implement an SMS and FDM, appropriately scaled to the size of your operation, to detect and correct unsafe deviations from company procedures before an accident occurs.
    • An SMS is an effective way to establish and reinforce a positive safety culture and identify deviations from standard operating procedures so that they can be corrected.
    • Collect data through an FDM over the entirety of the operation; this is the only means an operator has to consistently and proactively monitor its line operations. FDM should be a nonpunitive system.
  • Use analysis tools provided by associations and the FAA’s InfoShare to identify safety trends.
  • Incorporate a CFIT-avoidance training program that addresses current TAWS technologies relevant to your operational environment.


  • Require all Part 135 operators to install flight data recording devices capable of supporting an FDM program and to establish SMS programs.
  • Work with Part 135 operators to improve voluntarily implemented training programs aimed at reducing the risk of CFIT accidents involving continuing flight under visual flight rules into instrument meteorological conditions, paying special attention to human factors issues.

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