TOKYO (REUTERS) - Their smart uniforms are mothballed, their income has fallen and some are getting under their wives' feet at home.

The grounding of Boeing Co's global fleet of 787 Dreamliner passenger jets due to undiagnosed battery problems is taking its toll on the hundreds of pilots specially trained to fly the high-tech, fuel efficient plane.

In Japan, the 350 or so pilots at All Nippon Airways Co (ANA) and Japan Airlines Co Ltd (JAL), which operate around half the 50 Dreamliners in service, have been kicking their heels at home since the planes were idled in mid-January - an enforced rest period that is beginning to grate.

"For the first two weeks after the grounding, the 787 was in my dreams. It's the first time I haven't flown for this long,"one ANA Dreamliner captain told Reuters. He asked not to be named as he was not authorised to talk to the media. "It's like I'm rehearsing for retirement. My family teases me, saying I'm unemployed."

Without planes to fly, the pilots - who have up to three months intensive training for the 787 - expect their monthly pay to fall by as much as 30 per cent. They have mostly been assigned "blank" days - an industry term for pilots who are not on duty, staff at the airlines said. ANA has told its Dreamliner pilots they will undergo simulator refresher training next month, the pilot said.

Air safety investigators don't yet know what caused lithium-ion batteries to overheat on two 787s last month. ANA has said it plans not to use the plane until the end of May, while JAL has for now said it won't fly the Dreamliner until March 30.

INCOME DENT

Dreamliner pilots at Japan's two biggest airlines are not currently allowed to fly other aircraft, even though they have previously flown other planes including Boeing 777s, said staff at ANA and JAL - a sidelining that is hitting their wallets.

ANA pilots are paid 20 per cent to 30 per cent of their salary - a captain can earn more than 20 million yen ($269,000) a year - dependent on the hours they fly, including overtime and late night allowances, another of the airline's 787 pilots said. JAL, where more of a pilot's income depends on hours flown, has decided to add a special allowance to 787 pilots' salaries, said one employee at the airline.

"The salary is higher than what many people are paid, but because the Dreamliner pilots are not getting the money they had expected to get, some pilots are facing economic burdens," said the second ANA Dreamliner pilot. "This situation is not the company's fault, and it's hard for the firm to take action until the cause of the incidents is clear."

To get back in the cockpit, pilots would need to go through re-training on other planes, said airline employees familiar with the situation - a process that could take months and create a training backlog for non-Dreamliner pilots, too.

"With no outlook on when flights will be resumed, we are not currently considering specific measures for pilots, such as switching them to other aircraft," said ANA spokesman Ayumi Kunimatsu. At JAL, pilots were doing some training to keep up their licenses, but there were no plans to switch them to other planes, said an airline spokesman.

Boeing last week gave United States aviation regulators its plan to fix the 787's volatile lithium-ion batteries.

SPORT, DIY, GARDENING

The pilots Reuters spoke to said the 787 is easy to fly, though one was wary about any quick fix to the battery problems.

"Personally, I'm not satisfied by Boeing's proposals as the fundamental cause has not been identified," he said. "I want to fly, but I won't until it's certain the aircraft is safe." As they wait for the all-clear, pilots' routines have been turned upside-down.

One of the pilots, used to constant jet-lag and skipping meals because of his flight schedule, now eats three home-made meals a day. He's put on weight and says his uniform has become a little tighter. For now, he's playing more sport and reviewing his flight manuals. The second pilot said he's keeping busy with gardening and do-it-yourself projects around his home. He also checks regulators' websites for updates on the 787 investigations.

Both are trying to make the best of the unexpected break, but they have concerns.

"Honestly, I'm worried because I don't know when it will be resolved. The longer I don't fly, the more negative impact it has on my skills to operate the plane," said one.

"Pilots are better off flying," said his colleague.