Tang saw a UFO

[tangaroa]

While on a cross-country flight today, I saw a very fast two-engine jet heading east over Colorado. Since I couldn't identify what type of aircraft it was, it is a UFO. Other notable features:

• It flew solo. There was nothing else in the area.
• It flew about level with civilian airliner traffic, perhaps a bit higher.
• The exhaust was black and vertical, suggesting gravity taking down some dirty and heavy exhaust. Perspective probably caused an optical illusion as well.

I wonder if it was an SR-71 or whatever they're planning to replace it with. It was too far away to see any detail.