Every now and then, a story will come up about a few commercial flights who cross path with a stealth aircraft like the B2. I'm just wondering, since B2 is stealthy and most certainly won't appear on air traffic control radar. And the stealth aircraft will be flying in radar silence mode. How will they avoid collision with the airliners if they happen to cross into a busy airspace?
For starters, the term more often used is LO for Low Observable. This is due at least in part because people have all sorts of misconceptions about what 'stealth' is.
Now for B-2 operations, what they are doing is going to depend on what the mission is, and where they are while in flight.
Generally speaking, the only times a B-2 would be operating in 'busy' or congested air space is either when overflying the US, or the strike target is completely surrounded by congested air space or is in an area of congested air space.
When flying over the US, the B-2 is not going to operating under EMCON and as AD mentioned, there is a special reflector designed to increase the RCS of an aircraft which the B-2 would extend. After that, once the B-2 switches to operating under EMCON, the B-2 would fly an ingress and ergress route mapped out to be away from most air traffic routes, as well as in areas of minimal radar and other sensor coverage. Given that the B-2's operate either from the continental US or Guam, much of the time the B-2 would be over open ocean, and there are vast areas which see little regular air traffic.
-Cheers