Employees at the Kennedy Airport air-traffic control tower are under federal investigation for apparently allowing a school-age kid to give directions to pilots. The youngster, seemingly under adult supervision, makes five transmissions to amused pilots on a tape obtained by Channel 26 in Boston and confirmed as genuine by the Federal Aviation Authority. One exchange went like this: JFK TOWER: JetBlue 171 contact departure PILOT: Over to departure JetBlue 171, awesome job. A male voice