The U.S. Air force has ordered additional rescue radios for aircrew and upgrades to the rescue systems ground station network from Boeing.

Boeing said it will supply the Air Force with 336 of its Combat Survivor Evader Locator, or CSEL, radios under an award worth $9.7 million.

"CSEL radios save lives, so we are honored to support the United States military with this continued production," said Steve Capps, Boeing CSEL program manager.

Pilots and aircrew downed in danger zones use the radio to transmit locational and situational information using a two-way voice and data line-of-sight system, or beacon or over-the-horizon communication paths, Boeing said.

The new radios being delivered include a non-GPS beacon and capabilities for secure texting.

Base station upgrades by Boeing will involve the use of new hardware and software for faster communication speeds, as well as enhanced network and information security.

More than 54,000 CSEL radios have been delivered by Boeing to the Department of Defense, Boeing said.