3 ms·

Just making sense of the numbers to give a perspective: While at 600 feet, the “newer” first officer inadvertently pushed forward on the control column for abo

by mrb 2y ago

Just making sense of the numbers to give a perspective: While at 600 feet, the “newer” first officer inadvertently pushed forward on the control column for about 3 seconds. In the span of 3 seconds the plane dropped from 600 to 400 feet. Then the situation was corrected and the airplane climbed. So if the first officer had kept the same rate of descent for 6 more seconds, it would have crashed. The article quotes the rate of descent as 4000 feet/minutes. Some more details here: https://www.bnnbloomberg.ca/southwest-plane-plunged-within-400-feet-of-ocean-near-hawaii-1.2085519 https://www.bnnbloomberg.ca/southwest-plane-plunged-within-4... Edit: for the curious here is the flight data: https://www.flightaware.com/live/flight/SWA2786/history/20240412/0427Z/PHNL/PHNL https://www.flightaware.com/live/flight/SWA2786/history/2024... and the track log: https://www.flightaware.com/live/flight/SWA2786/history/20240412/0427Z/PHNL/PHNL/tracklog https://www.flightaware.com/live/flight/SWA2786/history/2024... you can see at around Thu 4/11 at 10:12:47 PM PDT the airplane made the rapid descent, then climbed back up quickly. However the ADS data shown by flightaware is too granular (one data point every 16-18 seconds) so we see the minimum altitude as 875 feet, but in reality the plane went lower. Apparently some other site (ADS-B Exchange) has more granular data, but I don't have access to it and am too lazy to create an account (is it free?)

roomey 2y ago
Well keep in mind with the stick forward the rate of descent would increase, and also the speed making pulling up much harder
- Stratoscope 2y ago
  Actually, higher speed makes it easier to pull up. You have more lift and more control authority. As long as you don't exceed the aircraft's structural limits, airspeed is your friend. It's when you are low and slow and try to pull up with the elevator that you may stall the aircraft. You need to push the throttle to gain some airspeed.
  - Xerox9213 2y ago
    For some reason I pictured Mario 64 with the wing cap while thinking out your examples.
  - cjrp 2y ago
    I can see it being harder on a GA aeroplane (more airflow over control surfaces making them harder to deflect), but not sure the same applies on hydraulic controls.
    - Stratoscope 2y ago
      Control surfaces work the same whether you are manipulating them with a direct mechanical connection or have hydraulic assistance. It's not a question of whether you are strong enough to move the flight controls. The only thing the hydraulics do for you is to reduce your effort in moving those controls. Control surfaces don't magically make the plane go up or down, or left or right. The only way they work is by pushing against the air flowing over them. If there is not enough airflow over the actual controls - ailerons, elevator, rudder - you won't be able to control the airplane. And if there isn't enough airflow over the wings, they won't provide lift. That is when you stall and lose all control, until you find a way to increase your airspeed and get some air moving over the wings and flight controls, so they have something to push against. Source: my basic pilot training where I practiced stalls and spins and all kinds of loss of control.
      - xvinci 2y ago
        > It's not a question of whether you are strong enough to move the flight controls. Anybody who flew a badly trimmed plane at high speed will disagree. Of course more airflow over the wings will mean your GA cessna 172 controls require more human strength to operate. They are also more effective as you say, but that's not what the previous poster meant.
        Stratoscope 2y ago
        That's an excellent point, thank you for noting it.
yieldcrv 2y ago
That 3-6 second time gap seems similar to what I do in a car every day, not coping just an observation.
- piva00 2y ago
  Now compare the inertia your car has vs a jetliner.
wkat4242 2y ago
Strange that the GPWS didn't kick in. This sounds like exactly the scenario for it. Or perhaps it didn't because they were on approach?

by mrb 2y ago

roomey 2y ago

Well keep in mind with the stick forward the rate of descent would increase, and also the speed making pulling up much harder

Stratoscope 2y ago
Actually, higher speed makes it easier to pull up. You have more lift and more control authority. As long as you don't exceed the aircraft's structural limits, airspeed is your friend. It's when you are low and slow and try to pull up with the elevator that you may stall the aircraft. You need to push the throttle to gain some airspeed.
- Xerox9213 2y ago
  For some reason I pictured Mario 64 with the wing cap while thinking out your examples.
- cjrp 2y ago
  I can see it being harder on a GA aeroplane (more airflow over control surfaces making them harder to deflect), but not sure the same applies on hydraulic controls.
  - Stratoscope 2y ago
    Control surfaces work the same whether you are manipulating them with a direct mechanical connection or have hydraulic assistance. It's not a question of whether you are strong enough to move the flight controls. The only thing the hydraulics do for you is to reduce your effort in moving those controls. Control surfaces don't magically make the plane go up or down, or left or right. The only way they work is by pushing against the air flowing over them. If there is not enough airflow over the actual controls - ailerons, elevator, rudder - you won't be able to control the airplane. And if there isn't enough airflow over the wings, they won't provide lift. That is when you stall and lose all control, until you find a way to increase your airspeed and get some air moving over the wings and flight controls, so they have something to push against. Source: my basic pilot training where I practiced stalls and spins and all kinds of loss of control.
    - xvinci 2y ago
      > It's not a question of whether you are strong enough to move the flight controls. Anybody who flew a badly trimmed plane at high speed will disagree. Of course more airflow over the wings will mean your GA cessna 172 controls require more human strength to operate. They are also more effective as you say, but that's not what the previous poster meant.
      - Stratoscope 2y ago
        That's an excellent point, thank you for noting it.

yieldcrv 2y ago

That 3-6 second time gap seems similar to what I do in a car every day, not coping just an observation.

piva00 2y ago
Now compare the inertia your car has vs a jetliner.

wkat4242 2y ago

Strange that the GPWS didn't kick in. This sounds like exactly the scenario for it. Or perhaps it didn't because they were on approach?