Yes, There were at least 4 trans Atlantic runways designated for aborts at any one time during the program, sometimes changing, and always with 2 "active" for a

Yes, There were at least 4 trans Atlantic runways designated for aborts at any one time during the program, sometimes changing, and always with 2 "active" for any given launch, staffed with a small city of NASA and military response personnel. From memory, I think there was generally one each in Africa, GB, mainland Europe, and Azores at any given time. Along with additional sites in Bermuda and Canada (or other US East coast sites) on most post Challenger flights, which weren't specially staffed. The interesting thing about the added sites post-Challenger, Bermuda was at an US military base. But Canada & other East coast sites were normal airports, with no training or added staff. The shuttle would have had to follow the same FAA emergency landing procedures as if it were a Cessna out-of-fuel, including contacting ATC and directly contacting local traffic at uncontrolled sites. These were viewed as "modified RTLS" aborts, and were realistically not much more survivable than an actual RTLS.