So - we wanted to use our uber app when we arrived to go to central Bucharest, and saw that cars were available in a few minutes in the "domestic arrivals car park".
Took us two attempts to sort this, so:
- when you arrive at international arrivals, turn left and go down the stairs by the cafe to exit on the floor below, which is domestic arrivals.
You'll see a concrete car park opposite - walk right through it and exit the other side - you'll see a small parking area with vans in it, right by a roundabout and across the road is another parking area.
If the uber has not arrived, just wait by the vans and flag it down. If it has, it's going to be in the parking area across the road.
Superb experience with Uber - about £8 in UK currency for mercedes to Radisson Blue.