Runway 19 at Ronald Reagan-Washington National Airport is offset from the runway in order to avoid restricted airspace over the US Capitol. If you fly this ILS approach like any other, you will end up on southbound I-495!!
Does anyone know how to properly use the ILS approach for runway 19?
I am very familiar with the approach. I haven't made that approach as of yet. If what you say is true you are off course by about 10 KM, in other words you are too far west to make this approach. If you would have said I-395 and wound up southbound on it I could help. I'll have to try this one sometime. You must be picking up a incorrect becon of some sort. This runway is a ILS runway to be sure.
I haven't looked at FS9 to see what approaches exist for DCA but in the real world, there is no ILS approach to Rwy 19 because of the Prohibited Area that a/c would have to cross on the final approach. Instead, there are two LDA (Localizer Directional Aid) approaches. One approaches on a heading of 137 degrees and the other on a heading of 147 degrees and then turns to runway heading on close final.
LDA approaches are fairly rare and the aircraft must have special equipment and the pilot must have special training to request or accept an LDA clearance. The only places they are used I am aware of is in situations such as DCA where an ILS cannot be flown and at large airports such as SFO where there are closer than normal parallel runways.