BLKWLF12 USAF BACN GLEX on final approach at Al Dahfra AB, Abu Dhabi after appearing heading west over Arabian Sea
Battlefield Airborne Communications Node
The U.S. military uses various datalink systems to exchange tactical information, and many are not capable of working together. For example, a U.S. Air Force F-15 can use its Link-16 system to exchange target information with a U.S. Navy F/A-18. However, the F/A-18 could not exchange information with a USAF B-52 or B-1 bomber. The advanced F-22 can connect with other Raptors via datalink but can only receive over the standard, legacy Link-16 datalink used by most allied aircraft. This lack of compatibility between different platforms is a major obstacle in all those theaters where air assets from many services are called upon to provide support for ground troops of different nations. Additionally, the complicated joint operations required to engage a modern integrated air defense system are greatly simplified by exchanging target information via datalinks. The BACN system is also used to link ground troops and Forward Air Controllers (FACs)/Joint Terminal Attack Controllers in a non-line-of-sight (LOS) environment. For instance, in the rugged, mountainous terrain of Afghanistan, troops are not always able to establish LOS communications with close support aircraft overhead. Moving position or relocating to higher ground could be fatal in a combat situation.
https://theaviationist.com/2020/01/27/u-s-air-force-e-11a-bacn-battlefield-airborne-communications-node-aircraft-crashes-in-afghanistan/