Japan Airlines has banned its pilots from drinking alcohol 24 hours before a flight during stopovers, according to the company.
The decision follows a recent case in which a male copilot had about 10 beers on the eve of a flight and was not able to fly.
In October last year, another JAL copilot, who has since been fired, was arrested in Britain in connection with heavy drinking. Following the incident, JAL prohibited all pilots from drinking before flights in stopover locations.
The company subsequently lifted the ban in April after tightening the alcohol test conducted before each flight and setting up other preventive measures. On the evening of June 19, however, a male copilot drank 10 beers during a stopover and was unable to board a flight the following day that was scheduled to fly from Hokkaido to Haneda Airport in Tokyo.
Since April, there have been two more cases of a JAL or group company employee becoming unable to fly due to drinking, prompting the airliner to issue a ban on June 23 that prohibits its pilots from drinking alcohol 24 hours before a flight during stopovers.
In October, last year Japan Airlines pilot Katsutoshi Jisukawa was found to be nine times over the alcohol limit as he prepared to fly a passenger jet from Heathrow Airport.
The Jisukawa failed a breathalyser test 50 minutes before he was supposed to fly a Boeing 777 with 244 passengers onboard.
According to the BBC the Judge sentencing the pilot said the prospect of him flying the plane in such a state was "too appalling to contemplate."
He was sentenced to 10 months in prison by a UK court.
Japanese Airlines' vice president Yasuhiro Kikuchi told reporters that the incident had changed the company's approach to the problem.
"As an organisation we are going to work together to prevent this happening again," he said.