Current event, I hear them all the time. love it!
The massive NATO Frisian Flag exercise is a large air live exercise held
in the Netherlands. The exercise is flown from Leeuwarden Air Base in
the northern province of Friesland and can be compared to Red Flag,
Green Flag and Maple Flag exercises in North America. Leeuwarden AB is
one of two F-16 Main Operating Bases of the Koninklijke Luchtmacht - KLu
(Royal Netherlands Air Force - RNLAF). It is home to RNLAF 322 Squadron
and 323 TACTES Squadron flying F-16 MLU fighters, as well as 303 SAR
Squadron flying the AB-412SP helicopter. 323 Tactical Training,
Evaluation and Standardisation (TACTES) Squadron organises Frisian Flag.
The exercise's history dates back to 1992, but was first named Frisian
Flag in 1999.

Among the more than sixty 2012 participants are
Royal Netherlands Air Force F-16's, Belgian Air Force F-16's, German Air
Force Eurofighter EF2000 Typhoons, Royal Air Force (RAF) Eurofighter
EF2000 Typhoons, Swedish Air Force JAS 39 Gripens, Finnish Air Force
F-18C Hornets, Polish Air Force F-16C/D Block 52+ fighters and Royal
Norwegian Air Force F-16AMs. Enjoy the sound of freedom! Footage made
with a Sony HX9V.