I did some research and minimum vertical separation used to be 2000ft but it changed to 1000ft in 2002 and they want to change it to 500ft on american territory. Is this correct? Why they wouldn't change it to 500ft on European territory also ?
2nd question:if aviation is evolving yearly, then airspace is getting more and more crowded. there is Concorde who has retired but used to fly at 60.000ft for example, why instead of designing new aircraft to fly higher, they would reduce the service ceiling ? I heard that from an engineer but I don't find an explanation. Statistically, they are reducing the service ceiling. Can anyone give an opinion? example? Thanks.