US authorities have lost track of who owns more than 100,000 private and commercial aircraft.
The Federal Aviation Administration (FAA) fears this could be exploited by terrorists and drug traffickers.
The records are in such disarray that the FAA says it is worried that criminals could buy planes without the government's knowledge, or use the registration numbers of other aircraft to evade new computer systems designed to track suspicious flights.
It has ordered all aircraft owners to re-register their planes in an effort to clean up its files.
About 119,000 of the 357,000 aircraft on the US registry have "questionable registration" because of missing forms, invalid addresses, unreported sales or other paperwork problems, according to the FAA. In many cases, the FAA cannot say who owns a plane or even whether it is still flying or has been junked.
Already there have been cases of drug traffickers using phony US registration numbers, as well as instances of mistaken identity in which police raided the wrong plane because of faulty record-keeping.
Next year, the FAA will begin cancelling the registration certificates of all 357,000 aircraft and require owners to register anew, a move that is causing grumbling among airlines, banks and leasing companies.
"We have identified some potential risk areas, but I think we're trying to eliminate as much risk as possible through the re-registration process," said FAA spokeswoman Laura Brown.