The annual Andrews Air Force Base Joint Service Open House and Air Show starts today and runs through Sunday. Metro says they’re ready for the large crowds: they plan to use 190 free shuttle buses to ferry attendants to and from the base, which is closed to civilian automobile traffic. The shuttle buses will depart both from the Branch Avenue Metro station, and from FedEx Field.

Of course, the big event coincides with ongoing switch replacement work at Mt. Vernon Square, so Green line riders aren’t going to have an easy time getting to and from Branch Avenue. Green Line trains will leave Branch Avenue only every 24 minutes toward the Greenbelt station. You can read more about the weekend delays on the Yellow and Green lines here, but if you plan to take public transportation to the event, you should really just factor in a huge chunk of time and check your impatience at the door.

The Joint Service Open House is running from 8 a.m. to 5 p.m. today, Saturday and Sunday, and will feature performances from the Blue Angels, Golden Night’s parachute team, and more. Just remember, the last shuttle bus heading to the show leaves at 2:30 p.m., so if you want to catch the Blue Angels, make sure you get there before then. Full schedule is here.

Photo from the 2007 Joint Service Open House and Air Show by SuperTopher