India, Sept. 21 -- A telecommunications equipment outage has grounded hundreds of flights at the Northeastern United States' most critical aviation facilities, exposing persistent vulnerabilities plaguing America's air traffic control system. Philadelphia's Terminal Radar Approach Control facility lost its primary communications circuit on Monday morning, forcing controllers to activate backup systems only to discover the fibre optic cable serving the secondary network had been severed.

The cascading failures triggered immediate ground stops at Newark Liberty International Airport, John F. Kennedy International Airport and LaGuardia Airport, halting departures and arrivals as air traffic controllers grappled with degraded communication c...