The letter said agency inspectors first obtained the study during an inspection at the company in December 1987.
An agency inspector can call the pilots by radio during the show and can stop the event if necessary.
When a plant inspection is completed, agency inspectors typically issue a report to a company, listing any deficiencies they have found.
The allegations of misconduct were never forwarded to agency inspectors.
Japan already uses so much plutonium that several agency inspectors are permanently stationed there.
Instead, the airlines are for the most part left to police themselves, with agency inspectors checking the paperwork.
The second is that a significant number of agency inspectors still lack training on the planes and equipment they are assigned to oversee.
A team of agency inspectors arrived in the Iraqi capital on Friday.
He said agency inspectors will now require the airlines to demonstrate that their contractors comply with regulations.
When agency inspectors went to the plant that made the peanut butter, the company acknowledged it had destroyed some product but declined to say why.
