The airspace surrounding Washington DC is some of the trickiest airspace in the United States. Multiple layers of secure airspace around the US capital and a number of Class B primary airports within within the area set up after 9/11, make the area daunting for most pilots.
Flightradar24 estimates there can be as many as five thousand aircraft flying in the United States at any given time, and as many as one thousand of these can be within 200nm of this airspace .
Shortly after 2001 the FAA implemented a dual layer of security around the US capital district. The inner ring of airspace within the DC SFRA (Special Flight Rules Area) is known as the FRZ (Flight Restricted Zone or "Freeze"). This airspace is forbidden to all operators without explicit TSA or DoD clearance.
According to AOPA  since the creation of the FRZ there have been over 1,000 unauthorized flights, known as airspace incursions. Despite all of the incursions being determined as inadvertent, several of those incursions have come close enough to the Capitol and the White House that evacuation of these buildings and other federal office buildings was required.
General aviation pilots have accounted for almost all (88 percent) of the violations of restricted airspace, with "pilot error" listed as the biggest contributor.
Spidertracks conducted an Air Tour around the United States this summer covering one million square miles and had a chance to go see some operators at the JYO (Leesburg, VA) airport which lies just under IAD Class B Airspace and just inside the Washington DC SFRA.
In order to fly into the DC SFRA (excepting a few specific areas) you need to be on an active flight plan regardless whether you are VFR or IFR. Although a specific kind of flight plan is needed for VFR flight into or through the DC SFRA.
On the perimeter of the DC SFRA, there are a number of ‘gates’ defined by radials at a 30NM distance from the DCA VOR. As you file your flight plan to fly into or through the DC SFRA, you’ll identify which gate(s) you plan to transition through. Each gate has their own assigned frequency with the Potomac TRACON.
So what about the areas where a DC SFRA flight plan is not required? One of them is called the ‘Leesburg Maneuvering Area’ (LMA) and it allows a greater freedom of movement within the DC SFRA in the JYO area. Pilots arriving into and departing from JYO via the LMA are required to squawk a special non-discrete VFR transponder code. No flight plan is typically needed for flight in the LMA, however if you're going to conduct pattern work at JYO, a flight plan is needed for that.
Real-time positioning data can help eliminate any ambiguity over where you are and the lifetime storage of your tracks mean that you can prove your location at any time in the past if required.
The tracking data from the Spidertracks system below shows how we arrived into and departed the LMA during our recent visit to JYO overlaid onto a Skyvector sectional chart in the Spidertracks platform.
The rules in the DC SFRA are always evolving. Prior to any flight in or near the DC SFRA, make it a point to educate yourself thoroughly from a current, legal source about what is required of you and your aircraft while in or near the DC SFRA.
More information about the DC SFRA can be found on the DUATS website at http://duats.com/help/dcsfra.pdf and remember to always check NOTAMS.
1 - http://www.flightradar24.com/38.44,-100.48/5
2 - http://www.aopa.org/Advocacy/Air-Traffic-Services-,-a-,-Technology/Air-Traffic-Services-Brief-FAA-Special-Awareness-Training-for-the-Washington-D-C-Metropolitan-Area