"Mr. Stull did not tell us anything about witnesses who had seen the plane," Wisnewski told Der Spiegel. That's certainly possible, but they do exist, and they're not difficult to find.
One of them is Lee Purbaugh, a laborer from Shanksville. The moment that seemed "like an eternity" to him has remained deeply embedded in his memory. He says that an "unbelievably loud roar" caused him to look up at the sky, where the giant airplane suddenly seemed suspended "practically over my head." Seconds later, at 10:06 a.m., the Boeing plunged into the ground.
Another witness is named Eric Peterson. He was standing in his store when he heard the noise of the plane's engines. He stepped outside and watched the United Airlines jet until it disappeared behind a nearby hill. Then a fireball erupted. Peterson immediately jumped into his SUV and drove to the site of the crash.
When he arrived, he saw aircraft debris spread across a large area surrounding the impact crater, which he said was "still burning." According to Peterson, "bits of clothing were hanging" in the branches of the surrounding trees.
There was so much evidence of a plane crash lying around that FBI employees and crash investigators from the National Transportation Safety Board (NTSB) spent thirteen days recovering the wreckage. The heaviest piece of wreckage that was found, part of an engine, weighed almost a ton. This was certainly much heavier than the supposedly "indefinable 'scrap' found at the 'crash site' of flight UA 93," about which Wisnewski speculates.
Moreover, there was nothing particularly mysterious about the subsequent handling of the wreckage. For the duration of the investigation, the remains of the jet were placed under an FBI guard. Once the investigators had completed their search for evidence, the standard procedure following a plane crash was followed. The parts were returned to the owner of the aircraft. In the case of the United Airlines Boeing, the owner was the airline's insurance company, the United States Aircraft Insurance Group (USAIG), which is headquartered in New York.