Most American carriers operating big planes have been equipped with them for years.
If a female carrier is operating on her normal X she will not show symptoms.
A similar investigation last spring found that both carriers were operating safely.
The carrier now operates one 747 flight to London a day, down from the usual two.
Some private and public carriers operate within the boundaries of Tokyo.
Air China will be the nation's major international carrier, operating 32 overseas routes to 31 cities in 24 countries.
Both carriers are operating in bankruptcy, with plans to emerge later this year.
But Administration officials say they do not plan to reverse the course of deregulation under which carriers have operated since 1978.
In the modern Navy, carriers operated within visual range of each other only for photographs.
The carrier operated the following equipment all through its history: