Serco Inc. will continue to provide air traffic control systems and technology support to the Navy under an $11.4 million contract modification.

Under the terms of the agreement, Serco, of Vienna, Va., will furnish engineering, installation and technical support services for air traffic control systems, the Defense Department said Tuesday.

The Space and Naval Warfare Systems Center, in Charleston, S.C., made the award and will oversee the indefinite-delivery, indefinite-quantity contract.

The company will perform more than 90 percent of the work in Charleston and Vienna. The Navy expects it to be completed by August.

Serco ranks No. 61 on Washington Technology’s 2007 Top 100 list of the largest federal government prime contractors.