Airports are stepping up employee screening . The Transportation Security Administration has increased the number of employees who screen passengers at airports and on flights to more than 10,000 from about 5,200 in 2009, according to a report released Thursday by the Government Accountability CNN investigation found only two major U.S. airports conduct full employee screenings .
Airports are stepping up employee screening . Still , there 's never a 100 % guarantee of safety , airport official says . CNN investigation found only two major U.S. airports conduct full employee screenings .