I was on american airlines flight 2501 chicago to dallas today when a delta shaped dark colored craft flew very close under us than away from me heading east, i was in seat 16a the lady directly behind me seen it also and tryed to video it but it was gone to fast, there was a single plume behind with a heat signature circle behind craft , it was so close it startled me as i watched it emerge from under us and move east as i sat on the left side of the plane, i watched it make some abrupt turns and ascend then disappear soon there after with a heat signature or possible corona effect being last sighted at aprox time 6:15 central in the area of southern arkansas or northern texas, ( not sure of city or county ), i had no time to film it was going too fast, it's shape reminded me of a smal boat similar to a cigarette racing boat almost