1.   Another would add the harmless gas to fuel tanks while in mid-flight as a way to reduce vapors.

2.   Much more needs to be done to reduce vapors in fuel tanks that can be ignited more easily than once thought, the board was told.

3.   That approach is to eliminate all possible ignition sources and to reduce explosive vapors that build up in center fuel tanks.

4.   The safety board has focused on ways to reduce flammable vapors in the tanks.