11.   The Federal Aviation Administration formerly planned to use GPS to replace all ground-based navigation aids.

12.   The Middle East contract involves producing, installing and commissioning three instrument landing systems, two en route navigation aids and five distance measuring systems.

13.   The only thing missing was an electronic navigation aid to guide visitors around the acres of product booths.

14.   You need telephones today, you need navigation aids ...

15.   Newer planes have collision warning devices, sophisticated navigation aids and larger fuel tanks that cut down on the need for refueling stops.

16.   Some say a warning would have come too late, and that other airport navigation aids were working properly at the time of the crash.

17.   Some airports have outdated navigation aids and inadequate inspection and maintenance facilities and procedures.

18.   The Joint Chiefs of Staff will also consider upgrading helicopter navigation aids, the official said.

19.   Navigation aids have also been installed to help aircraft to land and take off.