snip We now have an answer to that question. What happened at the principal airport of the national capital was an accident that, as the new president put it in his initial reaction, should not have happened. He's entirely correct on that. A commuter jet and an army helicopter colliding above the airport is a disaster from the last century, rendered all but obsolete by the technological advances of the new millennium. But, as we learned, not quite obsolete. There is still a critical human element - and the control tower at Reagan National is not altogether reassuring on that...