Why Did a U.S. Spy Plane Disguise Itself as a Philippine Aircraft? 

The spy plane was detected above the hotly contested Yellow Sea. 
IMAGE U.S. Air Force photo by Master Sgt. Lance Cheung

On September 22, a U.S. spy plane was detected over the Yellow Sea but it was emitting a signal that was reserved for Philippine aircraft. 

The aircraft is a United States Air Force RC-135S reconnaissance plane typically used for espionage and counter-espionage missions. It was separately detected by the South China Sea Strategic Situation Probing Initiative (SCSPI) and aircraft movement monitoring agency Aircraft Spots.

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In a tweet, Aircraft Spots flagged the spy plane which was “miscoded.” 

As you can see, its flight path took a back-and-forth route over the center of the Yellow Sea, a hotly contested area between China, Korea, and Japan. After completing its mission, the U.S. spy plane dropped the Philippine hex code and reverted back to its assigned signal. 

Hex codes are used to identify different aircraft and their countries of origin as they fly over different airspaces in the world. 

But it seems like military planes around the world regularly pose as commercial aircraft when conducting missions. Just a day earlier before the U.S. spy plane was detected using a Philippine-assigned hex code, another one was detected using a different code while flying over the West Philippine Sea on September 21.

Common Practice for Military Planes

The U.S. is not the only country that does these “miscodes” when using military aircraft. In the last decade, the United Kingdom, the Netherlands, Turkey, France, Greece, Norway, Portugal, and Luxembourg—which are incidentally all members of NATO—have all used miscoded military hex codes to appear as civilian aircraft on radars, according to this index


While it seems common practice for military aircraft to disguise their hex codes, doing so creates risk for civilian aircraft. 

In 1983, Russia shot down a Korean Airlines KLA007 passenger flight in its airspace because they mistook it for a U.S. spy plane.

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Mario Alvaro Limos
Features Editor-at-Large
Mario Alvaro Limos is features editor-at-large at Esquire Philippines, and heads the Lifestyle and Esports content of SPIN.ph as its section editor. Email him at [email protected] and [email protected]
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