5 ms·

The granular data from FlightRadar24 paints an especially grim picture: a descent of 30,000 feet per minute (fpm) at about 400 feet above the ground. That seems

• kijin 8y ago
  30000 fpm == 540 kph == 292 knots That's not a particularly unrealistic speed for a plane that's flying straight into the water, especially if the engines were still producing thrust. The 400-ft altitude would have been recorded less than 1 second before impact.
  • phumbe 8y ago
    Agreed, but it also had a groundspeed of 360 kts. Combined speed is then 463 kts. It's not impossible, but getting to that speed from 295 kts at a relatively steady 5000 feet...I don't know what to make of it.
    • kijin 8y ago
      Yeah, that's weird. Gravity alone is unlikely to be able to accelerate a plane like that in such a short time. If the data is anywhere near accurate, the engines must have been blaring until the last moment... Were the pilots desperately trying to go up, not knowing which way was up? (It happened before with AF447.)
      • FabHK 8y ago
        1/2 mv^2 = mgh, so v = sqrt(2gh). If all potential energy from an altitude of 5000 ft = 1500 m got converted into velocity, we'd talk about 170 m/s or about 330 knots (and a free fall from that altitude would take about 17 seconds, t = sqrt(2h/g)).
      • jandrese 8y ago
        The radio said the weather was clear and calm at the site of the crash. Rescue operations are already picking body parts and aircraft debris from the water. The most likely scenario in my head is some sort of control surface malfunction. Given how quickly the debris was located I'm pretty confident that they'll get the black box and solve this mystery.
      • phumbe 8y ago
        > Gravity alone is unlikely to be able to accelerate a plane like that in such a short time Yeah, a quick (and very elementary) back-of-the-envelope energy calculation shows that gravity alone couldn't achieve that speed. [SEE EDIT] > Were the pilots desperately trying to go up, not knowing which way was up? We'll have to wait and see, but it was morning, and I think I heard that there was weather in the vicinity of the crash but not at its actual location. EDIT: That calculation was wrong. The aircraft had more energy at 5475 ft than it did at 3200, 7.73 seconds before the last data point.
      • avip 8y ago
        The AF447 manuscripts suggest the pilot deliberately pulled nose up, unaware of the expected stall practice.
        • barrkel 8y ago
          Pretty sure he was intellectually aware - all pilots have it drilled into them - just mentally frozen in a panic and hadn't made the kinesthetic leap of understanding.
          • kirykl 8y ago
            The stall alert shutting off when he pulled up didn't help the confusion.
            • handedness 8y ago
              There's an almost brilliant quality to the concept of a stall warning system that self-cancels when the angle of attack becomes too high, or the airspeed too low.
          • handedness 8y ago
            While many aircraft have been lost due to what you're suggesting, we know from the investigation report that this is not what happened in the case of AF447. As difficult as it is to believe for anyone who received their training in almost any other program, the crew of AF447 had never practiced a single stall recovery in an aircraft before that flight. In addition, the transcript shows that they were not mentally frozen in a panic and unwilling to act, but that they were poorly-trained to correctly identify the problem, something compounded by terrible CRM as they argued about it such that even those who had correctly diagnosed the problem were overruled after the time to test their hypothesis had been wasted in argument. Instrumentation issues also compounded the above, among other things. Lastly, the pilot who attempted to apply correct control inputs to recover had his inputs negated by a dual-control input system so mind-boggling that it could only have been conceived by a company with such a culture of arrogance-driven ignorance as Airbus.