The tendency of commercial airline pilots to rely on automated systems now represents the biggest threat to flight safety around the world, according to a new study commissioned by the Federal Aviation Administration. Pilots now struggle with manual flying tasks and in some cases fail to keep pace with changing technology in the cockpit, according to the Wall Street Journal, which saw a draft copy of the report. As a result, some pilots lack the knowledge or skills to properly control their planes, particularly in unusual situations.

The report acknowledges that automation has made commercial airline travel much safer overall. At the same time, when the 34-member panel examined reports from accidents, they found that about two-thirds of pilots had struggled with flying their planes manually or made errors with the onboard computers. Among other incidents, pilot errors and automated systems were found to have played a role in a 2009 Air France Airbus 330 crash that killed 228 people and the botched landing of an Asiana Aircraft Boeing 777 in San Francisco in July.