A Japan Airlines pilot who was arrested in Britain shortly before a flight for being drunk was almost 10 times over the legal blood alcohol limit for a pilot, London police said.
The incident came a day after another Japanese carrier apologised for multiple delays after a hungover pilot called in sick.
JAL executives told reporters in Japan that the co-pilot cleared an in-house breath test but aroused the suspicion of a bus driver taking him to the plane at Heathrow Airport on Sunday.
The co-pilot, identified as Katsutoshi Jitsukawa, 42, was arrested by British police and required to undergo a blood test that confirmed those results.
He had reportedly consumed two bottles of wine and more than 1.8 litres (nearly four US pints) of beer over six hours on the night before the flight.
"We are certain (the in-house breath test) wasn't conducted properly," JAL communications chief Muneaki Kitahara told reporters Thursday.
A spokesman for the London police said a test on the co-pilot taken 50 minutes before the flight's scheduled departure revealed 189 milligrams of alcohol per 100 millilitres of blood in his system -- almost 10 times the 20-milligram limit for a pilot.
The drink-drive limit in England is 80 milligrams.
The pilot later pleaded guilty before a court to being over the legal limit, and is expected to be sentenced on November 29.
The plane departed London after a delay of 69 minutes.
"The company sincerely apologises to the passengers and to all affected by the employee's actions," JAL said in a press release.
The incident came just a day after All Nippon Airways revealed a hung-over pilot had caused multiple flight delays.
The male pilot in his 40s called in sick after a night of drinking on the remote resort island of Ishigaki in southern Okinawa prefecture, the company said.
The last-minute sickie forced the airline to delay five flights linking Okinawa island and smaller regional islands, affecting 619 passengers.
Following the two incidents, the transport ministry urged airline companies to strictly comply with rules on drinking.
But under Japan's current system, while plane crew members are banned from drinking within eight hours of working, there is no legal limit set and breath tests are not required.
Airlines have their own regulations, with JAL saying its rules banned pilots from drinking 12 hours before flying -- a limit they now said would be pushed back to 24 hours.
The airline will now also involve airport staff in alcohol checks rather than allowing pilots to test each other, Kyodo news agency reported.
Transport Minister Keiichi Ishii on Friday told reporters that the government would look into tightening the rules on drinking by flight crews.
"We will use all possible means to ensure flight safety," local media quoted him as saying.
He reportedly said Tokyo would study rules in other countries to determine best practices.