US regulators are advising airlines to renew efforts to alert passengers of injury potential if they fail to fasten seatbelts during turbulence.
An "information for operators" alert, issued on 6 January, aims to increase public awareness of the "increased risk of injury to passengers and cabin crew members" when passengers ignore the seatbelt sign, says the Federal Aviation Administration.
Its action comes after three turbulence incidents on air carriers, and the FAA adds that its flight standards service analysis and information staff recently concluded that turbulence was the "leading cause of in-flight injuries".
Although the incidents are not identified, NTSB incident reports from 2010 show nine turbulence-related events during which passengers or cabin crew received injuries.
In one case 17 passengers and four crew members were injured when a United Airlines Boeing 777 flew through an isolated thunderstorm cell en route from Washington to Los Angeles on 20 July. The aircraft diverted to Denver.
Along with developing scenarios to train crew members for "quick response" to possible turbulence, the FAA recommends that carriers develop business card-sized warnings printed with a slogan - "Turbulence Happens: Click it, don't risk it" - and hand them to passengers who ignore crew instructions to buckle up.
Source: Flight International