Crossing planes [Planes at different heights]

Jay Reynolds

Senior Member.
This is a fairly complete general explanation of separation:

However, its possible these flights are at RVSM altiude, where other rules apply:

Its also possible that there was a violation.

A photogrammatic analysis could possibly tell you more, if done carefully:

One hint that the planes are not so close is lack of wake vortex effects on the contrails, but since they weren't persistent, it is hard to tell.
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Mick West

Staff member
It's pretty much impossible to tell a difference of a few thousand feet from the ground, and certainly not from a low resolution video.

So long as there's 1000 feet vertically between them, then it's fine, and in fact happens relatively frequently.

This si what it looks like from the cockpit:

And here's one with THREE planes crossing the path of another. All perfectly legal and safe: