NASA's WB-57F 59K in hight.


#1

jsc-aircraft-ops.jsc.nasa.gov/wb57/

I am not sure where it was located, but I lost its tracking at 59,000Feet . I glanced over, and the frist time I had seen 50K+ in my altitude list.

N928NA WB-57F

The website says they can do 60,000 feet —plus.