Re: I can't compete with a Nikon P900
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I don't think you have too much chance to compete on a purely optical zoom level - 2000mm is pretty big...while those superzooms may not be big sensors, can be noisy, can't track or focus all that well with moving subjects, etc - for pure distance work, they're in their element as long as it's daylight.
Of course, planes flying with contrails are at a mostly consistent altitude between 25,000-40,000 most of the time, there can be some variations...namely when it's colder and more humid, and the altitudes that form contrails can drop. If the P900 shooter happened to be shooting in those conditions, that might have produced contrails at 18,000 to 24,000, and your shot might have been of a plane at the upper end of that altitude, around 40,000. Obviously, the clarity of the shot can be affected by an additional 20,000 feet of distance to the subject...not to mention the atmospheric quality differences between warm and humid air and cool air.
The other factor is your own elevation when you took the shot. Someone photographing a plane with contrails over the Rocky mountains located in a city at 7,000 feet elevation will be significantly closer than someone shooting a plane at the same altitude from sea level. All told, there can be some pretty big swings in distance in comparative shots.
I also like to occasionally shoot high-altitude planes flying overhead when I'm in my pool - mostly due to curiosity about what planes are flying past and where they're going. I am the unfortunate victim of some of the worst possible conditions for such shooting: SE Florida, elevation sea level, extreme high heat and humidity, atmospheric pollution from urban sprawl, tropical cloud cover and humid moist air. Essentially, I need to be lucky to catch a break from the heat shimmer, a clearing in the clouds, and just the right moment to shoot, and even then, at sea level I'm always as far away from the planes as almost anyone would be.
An example of a mega-crop shot with an APS-C camera and a 100-400mm lens at 400mm of a plane flying over my house at around 30,000-35,000 feet:

Not as clear as the example from the P900, but enough that I could make out the Brazilian flag on the plane's belly and the general paint scheme, enough to know it was an Azul Airlines, probably an Airbus A320. The sky was very cloudy, but the clouds were fairly high that day - I found it interesting that the plane was flying right at the edge of the clouds, and the shadow of the plane's tail was visible in the cloud.
Another shot, not with as much detail, but ended up being interesting...same lens and sensor combo at 400mm - this one was not only at the 30,000 foot altitude or so, but also not directly overhead - it was several miles out from me as you can see by the angle I was shooting...it seemed a strange shape which is what made me take the shot - I then had to blow it up 100% for a 1:1 pixel crop, just to make out what it was:

Taken in late September 2017, I was able to make out that this was a USAF plane...and the largest one in the U.S. arsenal to boot - the ginormous C5 Galaxy.
To find out why it would have been flying over my house, further research online revealed that C5's out of Nevada were picking up supplies and personnel from Travis AFB in California, and shuttling them to Puerto Rico to help with hurricane recovery. This plane was headed westbound, likely back to Travis for more supplies and more people.
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Justin
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