[GH85Carrera]

https://theaviationgeekclub.com/air-traffic-controller-tells-the-story-of-when-he-asked-for-vertical-separation-to-an-sr-71-blackbird-crew-in-conflicting-route-with-a-concorde-supersonic-airliner/?fbclid=IwAR249Nop7HSXJ5uPnjCR1LyN_Blc-GTFd0FzA4upWIRhDh_1mEFs0OA3vfE

ATC got to talk to a SR71. The Concord was at 60,000 feet and the ATC wanted to be sure the SR71 was 4,000 feet above that.