the conference is in downtown balt, that is over a 60 mile trip, with some of downtown balt to drive. the person would have to find an open rental in downtown balt, get a car, and dump it at dulles. just getting out of balt, is no fun. very tight for two hrs.

i would be uncomfortable calling to be met by a service. the may not show up for an extra hour. at least you should be able to find a service that can find dulles.

i do not think you will find anything but a local balt street cab, but that's probably the only way to do it. try to ask the driver if he knows where dulles airport is, and hope to get a correct answer. maybe your hotel concierge can arrange a car.

if someone knows how to get a bwi cabbie to downtown, that would be preferable. good chance the driver at least knows that iad is in virginia, even though the person may not know where is virginia.

sat pm is not a slow time for intl flights out of iad. UA must have half a dozen leaving between 6 & 9, and i think each must be processed by an agent.