The landing gear bulge in the bottom. Many of the (/11 cts claim that a "pod" was seen on the underside of one of the WTC planes and that is proof(tm) that it carried a missile.

As for the planes, I sent my guess in via PM. It was more than that, but quite a bit less than the source states. From the picture the best that could be hoped for is a ratio like the JAL plane is 25% higher, or 75% higher, or similar as we have no way to judge the altitude. The answer as stated would have made the lower plane about 30,000+ feet up and that just seems like way too good of resolution for a handheld shot.

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I'm not evil.
An evil person would do the things I think up.