The UK air accidents investigation branch (AAIB) has issued a safety recommendation calling for Boeing to notify all 777 operators that they should change safety procedures during an emergency landing in the type.

The action follows the accident of a British Airways Boeing 777 at Heathrow Airport on January 17 when the aircraft landed short of the runway after the Rolls-Royce Trent 800 engines failed to respond to demands for more thrust. Nine passengers and four crew members were injured and the aircraft was declared a write-off. Boeing 777s operated by airlines in China, Japan, Hong Kong, India, Indonesia, Malaysia, Pakistan, Philippines, Singapore, South Korea, Thailand, Vietnam and many others will all feel the effects of the action.

Although the cause of the accident is unknown, the ongoing investigation has revealed that two fuel shut-off valves that were supposed to have closed as part of the emergency landing procedure remained open, causing a major fuel leak that, according to the AAIB, “could have had serious consequences in the event of a fire during evacuation.”

The valves will close only if the two independent sources of electrical power to them–the fire handles and fuel control switches–are operated in the correct sequence. The AAIB said the evacuation checklist leaves open the possibility that the sequence could be reversed and that this is what happened in the accident. The directive calls for operators to modify checklists to ensure the fuel control switch is set to cut-off before the fire handle is operated.