Ten minus Two?
Your piece on how airborne networks might evolve in the future ("10 Emerging Technologies," May 2005) is a bit behind the times. The ability of aircraft to communicate their identities and positions to other nearby aircraft, and to take evasive action if necessary, has been flying for many years. It's called the Traffic Alert and Collision Avoidance System, or TCAS. It equips planes with receivers that listen to the replies transmitted by other aircraft to interrogations from ground radars. A newer technology, called ADS-B, allows aircraft to broadcast their identities and positions.

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