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We learn more about what happened before the fatal Learjet crash in South Florida. Investigators found a large section of the tail, known as the left elevator, flying into three pieces nearly four miles apart. The NTSB says this means part of the plane broke away before impact, while some are now focusing on a dangerous high-altitude trap called the " coffin corner." We'll invite aviation expert Ken Christensen, a commercial pilot and former air crash investigator. Congratulations, sir, and thank you for joining the program. It is very tragic to learn about the details that led to this terrible accident.
What have you been able to determine from the details we have learned so far? I think with this crash in particular, a lot of the information is coming primarily from the co-pilot, as well as from air traffic control records about where the plane was actually flying. A lot can be understood from this. The plane apparently crashed at high speed, and the camera footage clearly showed that the plane had no horizontal stabilizer. This was very revealing in this plane crash. Yes, many believe that he probably broke away due to speeding. I know you were on the runway waiting for takeoff at Donald Trump International Airport when that ill-fated flight flew right over you.
People are talking, and many are discussing online something called "coffin corner," which such planes can encounter at high altitudes, and that the way out of it is not to climb up like they do, but to descend. Can you explain this? Yes, actually, the higher the altitude, the higher your Mach number becomes, you accelerate, so you can get a stall at high speed if the plane is flying too fast, and it kind of coincides with the fact that if you fly too slow, you can also stall. This is why it's called the "coffin angle," and depending on the altitude and type of aircraft, it can range from three to five knots.
Oho. I suppose at this altitude with a Learjet it might not have been a factor, but it's a real thing that happens in aviation. You know, I was struck when we were talking to you before the broadcast by how you talked about the composure the co-pilot maintained throughout the descent. This also struck me when I listened to the audio recording. And you say we can learn a lot from what she was able to convey while the plane was in a dive That's right. So, some of what we learned initially is the normal radio exchange between an
aircraft and a controller. And again, it's the pilot who's not piloting who's talking. This is how most two-pilot crews operate. So the co-pilot or first assistant commander negotiated with the air traffic controller. At first everything was fine. They began to accumulate ice. They understood it. They asked for more altitude, the so- called climb, to get rid of the ice But for this you need to use air extraction from the engines. You waste some of the engine power to melt ice on the wings or control surfaces. And when you climb, you need power to climb. So this is not the best situation. In addition, they were above a thunderstorm front, where there was moisture, which significantly worsened the situation.
Yes, Ken, I wanted to ask about that because it seems like there are a few points here. It looks like they flew into a thunderstorm at full speed. I also saw discussion of what is called "Mach tuck", where the aerodynamics of an aircraft change as speed increases, which could lead to an uncontrollable attitude. That's quite right, John. "Mach pickup" is a real problem. So, while flying at cruising altitude, when ice forms on the control surfaces, it can be like an unbalanced wheel in a car that starts to vibrate. In aviation terminology, we call this high-speed flutter. As the control surface moves through the air flow, it may begin to vibrate. And this vibration can put the aircraft in a critical condition or lead to loss of control.
This can lower the nose of the plane and you begin a rapid descent, exceeding what is called the VNE speed-a speed that should not be exceeded, or, more simply, the design of the plane is designed for a certain range of speeds, and you can go beyond it. Then, due to the high-speed flutter, the control surface will vibrate up and down, and just like you bend a paper clip in half until it breaks in half, you can cause the structure to collapse by speeding the aircraft too high, and that's what seems to have happened. Oho. It's just terrible. Ahem. It seems like they didn't even have a chance. Ken, thank you for joining us. When this happens, their fate is already decided God, how terrible. Ken, thank you for joining us. Thank you for your
professionalism. I really appreciate it. Like and subscribe to get the latest Fox News on YouTube, and watch full episodes on Fox One.
