I am curious.  I am not a pilot by avid simmer.  I was flying (real life as a passenger) from KCLT to JFK at FL330.  I am always looking out the window.  Looking as forward as I can see thru passenger window, I see a Jet Blue plane at same altitude - seemed to be level coming180 degrees.  It passed parallel to us (opposite directions) same level at about 2000 ft away. I could easily read the "JETBLUE" letters on the plane.  I thought planes use alternating altitudes.  He was flying south - should he have been at FL320or FL340?  What is the allowable horizontal separation allowed?

Edited July 24, 20223 yr by paulyg123

Minimum vertical separation for IFR flights is 1000 feet employing RVSM (Reduced Vertical Separation Minima) procedures. 1000 feet vertical appears close and it is but safe.