Things you never want to see in D.C.

The F-16 that suddenly appears off our left wing is obvious.

It wags its wings as it goes by, and its engine, in afterburner, shakes the sky like an aerial earthquake.

An identical airplane that trails a few miles behind and slightly above us, however, isn’t visible to us at all. It’s there to intervene if we take some sort of hostile or evasive action.

Recently, AOPA staffer Bob Knill and I joined the Civil Air Patrol in a single-engine, fixed-gear GippsAero G-8 Airvan on an aerial exercise that gives the U.S. Air Force F-16 pilots based at Andrews Air Force Base some practice at identifying and tracking relatively slow-moving general aviation aircraft near the Washington, D.C., area.

Such intercepts have become all too common after the terrorist attacks of 2001. And they usually involve well-intentioned but navigationally challenged general aviation pilots who represent no threat whatsoever to national security. Still, to prepare for the chance that a terrorist in a GA airplane might someday present such a threat, the U.S. military regularly practices these intercepts in aircraft ranging from helicopters to supersonic fighters.

This particular exercise called Fertile Keynote (who makes up these names?) took place over Maryland’s Eastern Shore so as not to cause panic in our nation’s capital.

As CAP pilot John Henderson flew along a triangular route at 3,500 feet at the base of a restricted area (R-4006), the F-16s came at us from the southwest. Their transponders were on, so they showed up as fast-moving white blips on the Airvan’s Garmin MX20 multi-function display before they could be seen out the window. But when they showed up, flight leader Lt. Col. Christopher Hardgrave was quite conspicuous.

He simulated broadcasting on the guard frequency of 121.5 MHz to determine whether the intercepted aircraft’s radio had failed. Hardgrave rocked his wings and turned gently away signaling for us to follow. We didn’t, so he repeated the process.

With each repetition, his methods became more urgent.

On the fourth and fifth passes, he crossed our path from below in a hard climbing turn with the engine in afterburner and vapor condensing at the wing roots. This aerial “head butt” was an impressive sight, and one that no GA pilot wants to see except at an airshow.

Once Hardgrave and his unseen companion went home, we did something else that GA pilots aren’t supposed to do—at least not without permission. We flew deep into the flight restricted zone (FRZ), the inner sanctum of the Washington, D.C., Special Flight Rules Area, and got “sparkled” by a ground-based visual warning system.

The rapid-fire series of red and green lights placed within the FRZ is meant as a last-chance wake-up call for errant pilots telling them that they’re somewhere they shouldn’t be. The bursts of focused light are far brighter than any airport lights, and they seem to scream that something is definitely not right. The obvious message: Turn around.

This particular set of lights was at Andrews Air Force Base—home of Air Force One.