YOKOSUKA NAVAL BASE, Japan — Many families in Japan found themselves packed but with no place to go Friday as military commands waited for orders from higher commands that would begin a planned voluntary evacuation.

With uncertainty over when the military-assisted flights would begin, some families on their own began leaving behind the aftershocks and looming fears of radiation that have plagued Japan since the 9.0-magnitude earthquake struck on March 11.

Other families were still trying to collect information to make a decision on staying or leaving.

Anita White had little hesitation. A Navy spouse from Silverdale, Wash., she caught the 2:30 p.m. Friday shuttle with her children to Narita International Airport, even though they weren’t flying out until the next day.

“We were afraid the bus would be too full tomorrow,” said White.

White booked plane tickets Wednesday, a day before the military authorized voluntary evacuations. The most difficult part of remaining in Japan, she said, has been the confusion over exactly how much of a threat Yokosuka faces from the radiation coming from the Fukushima Dai-ichi nuclear power plant.

“Then there is also the uncertainty of when we’ll be able to come back,” she said.

White’s son, Nathan, 17, is a senior and hopes to graduate this year from Kinnick High School in Yokosuka, although those plans now seem less certain.

Laura Sheeks, a teacher at Naval Air Facility Atsugi, knew she would be among the last to be evacuated, because of a Friday order deeming her an essential employee. Instead, she decided to leave on her own.

“If I stay here, I need to continue to be worried about the [nuclear] plant and more earthquakes,” she said. “I’ve had enough earthquakes.”

At Misawa Air Base in northern Japan, leaders told the base community they need to know how many family members plan to leave Japan under a voluntary evacuation program announced Thursday.

Col. Michael Rothstein, commander of the 35th Fighter Wing, spent about an hour on the radio Friday explaining the voluntary evacuation plan. Rothstein said those wishing to leave need to immediately provide their names through their commands so Misawa can request air support.

“I’ve got to get that list of names and list of numbers,” Rothstein said. “You can’t wait to decide.”

Officials said they still don’t have details on when the flights might leave.

Rothstein said that family members can expect to make an interim stop at a military base in the region — possibly Guam, Okinawa, South Korea or Alaska — before continuing on to a final destination of their choosing in the United States. He said the current plan is to have families return to Misawa within about 30 days, but those traveling should plan for the possibility of being away longer than that.

Rothstein answered several questions from community members, including what the colonel intended to do with his own family.

He said he’s leaning toward keeping his family in Misawa, but planned to sit down with his wife before finalizing his decision.

“I’m not confident that I’m making the right decision,” he said. “That’s as honest as I can be.”

An occupational and public health expert who has studied radiation effects says that military officials in Japan should create a single, central source of information — just as the Centers for Disease Control and Prevention did in years past during the anthrax attacks and H1N1 flu scare.

“It would really help people if they knew at 12 o’clock today, I’ll get an update on e-mail or Twitter ... that has the best, latest information about health concerns,” said Lewis Pepper, a professor at Boston University School of Public Health.

Because that information will be complex data on radiation levels and types of radionucleotides present, expert interpretation is needed.

“You can’t just dump millirems and millisieverts on people,” he said. “You need qualified people to interpret it.”

Pepper said his best reading of the data available in the United States is that people on U.S. bases are far enough away from the stricken Fukushima nuclear plant to take a wait-and-see attitude.

The fact that the situation could worsen, however, may be too much for some.

“If individuals feel they can’t tolerate the psychological stress of it, and many people just can’t, they should leave,” he said.