裏筋

The pilots on this private jet were on the radio with air traffic control while it fell from higher than Mount Everest to a Florida street in about 80 seconds. You can hear them realize they aren't going to make it. Their trouble started right after a request that sounds totally reasonable. They asked to fly higher. This was a Learjet 60 carrying nine people from Austin to the Bahamas, a little over two hours into the trip. When they checked in with Miami Center at 35,000 feet, they were getting bounced around hard enough to swing their altitude 600 to 700 feet. They also had a thin layer of clear ice on the plane that the pilot called manageable. It was minus 47 Celsius outside. Then it started precipitating, so they asked to climb to 37,000 to get out of it, and Miami said okay. Climbing out of bad weather is standard stuff for pilots, and up that high it comes with a catch most of us have never heard of. The air is so thin that a jet has a weirdly small window of speeds it can safely fly. Go too slow and the wings stop holding it up, and if you go too fast, shockwaves start forming on the wings. Every thousand feet you climb, those two limits squeeze a little closer together. Pilots literally call the spot where they meet the coffin corner. A Learjet 60 normally cruises right around Mach 0.76, and its limit is 0.81. So even on a calm day it's flying pretty close to the edge, and turbulence knocks your airspeed up and down inside that window. Within seconds of starting the climb, the tracking data shows their groundspeed jumping from 437 to 505 knots as the jet started falling at almost 20,000 feet per minute. The pilot's mayday said the same thing. "We are in an overspeed condition, descending 20,000 feet per minute." Another call said they were banking. When you get those two at once, things get ugly fast. Once a jet blows past its speed limit, the wing can start pushing the nose down by itself, which adds speed, which pushes the nose down even harder. If the wings are tilted on top of that, the lift that normally holds the nose up is pointing off to the side. The nose keeps dropping and the plane winds into a spiral. Your gut tells you to pull back on the controls, and with the wings banked that mostly just tightens the spiral. You're supposed to level the wings first and only then pull up. Now try doing that inside a cloud where you can't see the horizon while the overspeed alarm is going off. By 12:49 Eastern they were down to 8,750 feet and dropping more than 32,000 feet per minute. That works out to about 360 miles an hour, straight down. At that speed the last 8,750 feet goes by in around 16 seconds. The dashcam video shows the jet coming in nearly vertical over Military Trail, with cars still driving on the road under it. It hit right next to a mobile home park. About 600 people who live there are being moved out, and officials say nobody on the ground was hurt, which is honestly hard to believe when you watch that fireball. The NTSB will probably take a year or more to officially say what caused this. The last thing on the radio was the controller repeating their tail number, November seven two two Bravo Delta, over and over, with nobody left to answer.