To avoid anyone getting lost when trying to get to the Udvar-Hazy part of the Smithsonian's Air Space Museum, here's the latest info. The shuttle coach that used to run between the original museum on the Mall & Dulles was discontinued for lack of customers and you now have to use public transport.
From the museum on the Mall, go out the back door & down to D Street (south under the rail bridge) and then west to the bus stop just before 7th Street. The 5A bus leaves on a slightly irregular schedule , check the latest times at
www.wmata.com/timetables/dc/5a.pdf Cost is $3.10 - exact change required but it does take $1 bills.
The 5A bus also stops just north of Rosslyn Metro (nearest metro from Ronald Reagan) about 15 minutes after leaving D Street and then takes about 45 minutes (or more with traffic) to get out to Dulles Airport. The stop is on the lower level by the parking shuttle & other ground transport. The Virginia Regional Transport shuttle to Udvar-Hazy picks up from the same stop, takes about 15 minutes to get there and costs 50c (exact change requested). First bus is at 10.30 & every 45 minutes on weekdays and 11.15 then hourly on weekends. If you miss the bus, it will cost you $10 - 12 for a cab!
Last bus back to Dulles is when the museum closes at 5.30 which easily makes the 5A at Dulles at 6.05.
As seen in the photo above, it's got some unique aircraft so it's well worth the trip.