In preparation for a possible labor dispute, Col. Jeffrey T. Geraghty, commander of the Arnold Engineering Development Complex headquartered at Arnold Air Force Base, has directed the reconfiguration of gates and installation of barriers. The Air Engineering Metal Trades Council (AEMTC) and the National Aerospace Solutions, LLC (NAS) are negotiating their collective bargaining agreement, which is set to expire at 11 p.m. today. If an agreement is not reached, NAS bargaining unit employees may strike and picket at the base entrance. The AEMTC represents more than 600 employees from 11 trade unions, and NAS is the test, operations and sustainment contractor at Arnold AFB.