Preventing Turbulence-Related Injuries in Air Carrier Operations Conducted Under Title 14 Code of Federal Regulations Part 121

​​​Turbulence-related accidents are the most common type of accident involving air carriers operating under Title 14 Code of Federal Regulations Part 121. From 2009 through 2018, the National Transportation Safety Board (NTSB) found that turbulence-related accidents accounted for more than a third of all Part 121 accidents; most of these accidents resulted in one or more serious injuries but no aircraft damage. This NTSB safety research report examines the prevalence and risk factors of turbulence-related accidents in Part 121 air carrier operations; assesses the effectiveness of policies, programs, technologies, and other applicable safety countermeasures; and makes recommendations for improving turbulence avoidance and injury mitigation.

Turbulence arises from eddies in the atmosphere and is typically categorized by its source, such as convection, nonconvective wind shears in clear air, mountain waves, surface features, and aircraft wake vortices. Like many accidents in aviation, turbulence-related accidents can often be influenced by multiple human, aircraft, environmental, and organizational factors. Over the past decade, the NTSB has determined the probable cause for numerous turbulence-related accidents and has issued safety recommendations for improving weather forecasting, dissemination of weather reports, and air traffic management practices to reduce the likelihood of aircraft encounters with turbulence. More recently, in 2017, the NTSB issued several recommendations addressing safety issues related to turbulence as part of its special investigation report Improving Pilot Weather Report Submission and Dissemination to Benefit Safety in the National Airspace System, SIR-17/02​.

Despite steady improvements in the overall accident rate for Part 121 air carrier operations, turbulence continues to be a major cause of accidents and injuries. This research examined safety issues related to the turbulence problem from a systemwide perspective. 

The NTSB’s research goals were to:

  1.  ​summarize the basic types and causes of turbulence; 
  2. describe the safety impacts of turbulence, including characteristics of and trends in turbulence-related accidents and injuries across Part 121 air carrier operations; 
  3.  examine methods used to reduce the likelihood of turbulence encounters and turbulence-related injuries in Part 121 air carrier operations; and 
  4. identify proven and emerging best practices and safety countermeasures.

To accomplish these goals, the NTSB used both quantitative and qualitative methods, including a literature review, aggregate analysis of aviation accident data, and interviews with a broad selection of government, industry, and other stakeholders. In addition, the NTSB conducted 10 detailed investigations of turbulence-related Part 121 accidents over the course of this research to provide relevant and timely case studies. ​​​​​