All, This morning caught Nighthawk 30 flight (probably H-3s, MCAF Quantico) on a local navigation training flight in the DC/Northern VA area. They were using 320.4 as an interplane freq. This is the first time I've heard this freq active. Normally they use 276.4 or 273.95 as an interplane freq. RON MIDDLE ATLANTIC MILCOM MARYLAND, USA