A shattered windshield, a pilot with his arm covered in cuts, and United Airlines Flight 1093 diverted for an emergency landing. The plane that covered the route from Denver to Los Angeles has become the aeronautical mystery of the moment after, apparently, something hit the cockpit at 11,000 meters above sea level.
What we know. The United States National Transportation Safety Board (NTSB) is investigating an incident that occurred Thursday with a Boeing 737 MAX 8 flying over Moab, Utah, at cruising speed. The plane was traveling at an altitude of 36,000 feet when a suspected impact occurred in the cockpit.
Photos of the incident show the captain’s side windshield completely splintered, the plane’s center console splattered with glass, and the pilot’s arm covered in small cuts and abrasions. According to initial reports, the captain “thought they had been hit by a piece of metallic space debris.” When they made an emergency landing in Salt Lake City, they ended up discovering a “3.5-inch” impact on the outer panel of the windshield, but the cabin did not depressurize.
Space junk? The plane’s windshield has been sent to NTSB laboratories for analysis, but researchers are not working on the hypothesis that it was a space debris impact, but rather part of a more mundane object that also flies higher than airplanes: a weather balloon.
Although space junk be a growing problemthe United States Federal Aviation Agency (FAA) considers the risk “minuscule” of a piece of satellite or rocket hitting an airplane. That it also injures a person on board has a probability of “less than one in a billion.”
The famous popularizer Scott Manley points out one of the main reasons for skepticism: modern satellites are designed to disintegrate into small pieces. Upon reaching cruising altitudes, these pieces are no longer hypersonic and have low impact energy.
So a balloon? If it wasn’t space debris, what could have broken the windshield and injured the pilot? One of the exterior images of the plane shows, in addition to the broken windshield, dozens of small marks and dents on the metal fuselage of the plane, just above the window, which could be an indication that they encountered a hail storm.
Hail is rare at 11,000 meters, but not impossible. However, the NTSB is working on the line of investigation that it was “a piece of a weather balloon data packet,” according to the specialized website AVBrief. These balloons and their payloads usually operate at 25,000-40,000 meters above sea level. Of course: if the piece was still tied to a balloon, it is strange that the pilot confused it with space junk.
The windshield failed. Whatever hit the plane, the photos suggest the windshield didn’t do its job. The cabin windows of a 737, Manley explains, have multiple structural layers: glass on the outside and inside, with a polymer layer in between.
The impact did not cause depressurization, indicating that the main structure and polymer layer held, but the inner glass layer fractured violently, projecting “glass dust” and small fragments toward the pilot, and causing the abrasions and cuts seen in the photos.
The crew descended to 26,000 feet after the incident to reduce the pressure differential over the damaged window, and landed without further complications. The definitive answer as to what hit Flight 1093 will have to wait for the forensic analysis the NTSB is conducting on that shattered windshield.
Images | JonNYC
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