> The spokesman said an Air Force investigation established the troubles began with the failure of the navigation guidance unit inside the missile. That is not

> The spokesman said an Air Force investigation established the troubles began with the failure of the navigation guidance unit inside the missile. That is not unusual, he said, because the guidance units have a finite life and must be replaced periodically. There must be more to it than that... "Fire!" "Err, Sir, the guidance unit has just indicated it needs to be replaced"