"WASHINGTON — WHEN mass murderers took over the cockpits of four American airliners on Sept. 11, 2001, one of the first things they did was turn off the transponders, so the planes would not register properly on civilian radar.
A few months later, the Council on Foreign Relations published a book, “How Did This Happen?” about the mistakes leading to that awful day. I wrote the aviation security chapter, which highlighted vulnerabilities in the way airliner transponders operate.
If the transponders had not gone silent on 9/11, air traffic controllers would have quickly realized that two jetliners en route to Los Angeles had made dramatic course changes and were bound straight for Manhattan. Instead, controllers lost precious time trying to figure out where the aircraft were.
At the time, I would have bet my life’s savings that the transponder, which broadcasts an aircraft’s location and identity, would be re-engineered to prevent hijackers from turning such units off. But nothing was done. Almost 13 years later, Malaysia Airlines Flight 370 sparked a lengthy worldwide search when, it appears, another transponder was turned off.
The issue today is exactly as it was on 9/11..."