Tracking Small Planes with GPS

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TR: As you alluded to earlier, future air-traffic control could be based on planes beaming out their GPS data, a technology known as ADS-B, that will join--and in some cases replace--radar-based monitoring. Will this help?

JH: The FAA is requiring ADS-B in the next 5 or 6 years, which will allow transmission of position and other aircraft states (such as velocity). This will initially be for commercial passenger aircraft, but the expectation is that it will be common for all aircraft. This will become part of the FAA's surveillance system. Examinations of radar tapes would be supplemented with GPS-based ADS-B data, which will be higher resolution and have a faster update. You will then still need an antenna in range to receive the information. If you don't, or if it's blocked by a building, you would still need that data onboard the plane if you wanted to recover this information after a crash.

TR: This crash has led to a political drumbeat for tighter restrictions on small planes around Manhattan, because of the apparent terrorism risk. What's your take on that?

JH: The interesting thing is that this event shows that small airplanes are not threats to buildings. There's all this talk about regulating planes more; but what this shows is that if you take a fully loaded small airplane and fly it into a building: the airplane bounces off the building. They don't have enough energy to penetrate and challenge the structural integrity of the building.

TR: This plane included a parachute designed to support the entire plane in an emergency. Could it have saved lives in this situation?

JH: The parachute is interesting, but it doesn't protect you from everything; at low altitudes it does not work because there is not enough time for deployment. It's not clear that at 500 feet or below they could have deployed it reliably.