1.   Several specialists in navigation said there are at least three lessons to be learned from these and other recent navigation problems.

2.   The apparent navigation problem, officials said, was caused by human or software error, not mechanical failure on the spacecraft.

3.   A U.S. fighter made an emergency landing at an airport in western Japan Thursday after developing fuel and navigation problems.

4.   An on-board guidance system worked, however, so the navigation problem was of no consequence, the official said.

5.   The men, who were on their way to Namibia, apparently made an emergency landing because of navigation problems, Rasheleng said.

6.   They were on their way to Namibia when they had navigation problems and were forced to make an emergency landing, he said.

7.   On their way to Namibia, they had navigation problems and were forced to make an emergency landing, he said.