The plane involved easily could have had 194 passengers on board (!), assuming that other transponders could also cause such confusion.
One solution is already available. Washington DULLES Airport. Already in use for many years. The major problem seems to be convenience, and heavy highway traffic.
Shutdown DCA airport, which is in the heart of the capitol city! Only the politicians have kept it open, from what I've read. Maybe this latest near-tragedy will knock some sense into them. They might counter with, "Oh no-we've gone to so much trouble and expen$e developing these 'safety procedures'........"
Would an interceptor jet be authorized to first try to fly just ahead in loose formation, and signal with a slight wing rock that a turn is required? This might be quite classified. When a C-130's exhausted, sleeping crew (just a very, very long duty period: our airline managements would love it) was headed the wrong direction in Southeast Asia many years ago, the US F-4 Phantom pilot, authorized to shoot it down, flew alongside, saw everyone slumped on head rests and cleverly cycled his afterburners (reheat). After a few times, the booming sound woke up either a pilot or the FE, who quickly woke up the rest and they turned around. "Hey Lieutenant, you want lo mein or cashew chicken, and start with a spring roll?" The F-4 pilot got free drinks for a while.
