Plane drops to 928 feet after autopilot set to 0 altitude
bbc.com
bbc.com
Ultimately the problem here was:
ALT mode was selected accidentally ALT SEL mode was selected later, but ALT mode wasn't disengaged manually and engaging ALT SEL while in ALT mode doesn't disengage ALT mode.
A combination of other factors (rushed during takeoff, interruptions from ATC, unfamiliarity with the Airport) caused the workload to be such that neither pilot picked up on the numerous subtle visual clues that showed that the autopilot was not going to do what they were expecting.
Luckily, after descending 500ft in about 18 seconds, audible warnings in the cockpit alerted the crew that things were going awry and they very quickly remedied the situation.
The article says a maximum decent rate of 4,300 ft/min, so almost 3 times faster than that. They were about 13 seconds from crashing into the ground if that rate held constant.
I can only speak to my personal experience and I don't have any sort of advanced pilot's license: I just did the very first one - PP/ASEL. In that course even prior to instrument training I was taught to not fly by the seat of my pants.
The way my flight instructor explained it the human body is easily fooled and will quickly adapt to a new normal. So you had as an example a pilot getting used to a slight tilt and assuming this is normal, so they keep correcting for the tilt and worsening their situtation.
Even as a lowly PP/ASEL I'd still validate any reaction by reading the instruments before assuming a feeling of falling is accurate. Would that take thirteen seconds? Hopefully not, but it would take more than one.
Combined with the idea that airline pilots do less and less hand flying and also have many inputs in the cockpit trying to tell them what's happening and therefore may need a few seconds to integrate all that data and then react with a potentially rusty skill I'd feel comfortable saying a subsecond response seems unlikely.
Why did it require audible warnings? How could any pilot not notice that they were coming down that sharply?
Not to mention, in limited visibility you simply can't trust your sensation of G forces. In the absence of visual stimulation, your mind can hallucinate the feeling of movement that doesn't match your actual movement. You can simulate this by standing with your feet together and closing your eyes.
If you read the UK Government report that is not what happened. The plane was at 1500 ft when it began to descend. At 1300 ft the warning sounds activated and the pilot reacted but it took another 300 ft of descent before the pilot was able to fully recover from the descent.
Poor reporting from the BBC.
At ~15 Metric Tons (33,000lb) take off weight it's a long way from a light aircraft. However, if your walking around these things, my personal view is a medium is around a Cessna Citation Mustang, double that and their large, and aircraft quickly get into huge and monsters.
Other criticisms aside, Britain's are some of the safest in the world, and I think it's because of the same approach.
I like that the report on the tank wagon has detailed pictures of failed welds and so on.
Maybe the one about the "loss of speed restrictions" would be of interest to HN, since it seems to be a software problem and its subsequent analysis.
https://www.gov.uk/government/organisations/rail-accident-in...
Low resolution mirror: https://drive.google.com/file/d/1P7czQkX_9_e7fBDYaFWG0Olwtpp...
High resolution mirror: https://drive.google.com/file/d/1ulgy8cGSrG7nT1_p6PmKlxTBBi_...
Original links can be found at: https://www.gov.uk/government/publications/air-accident-mont...
assets.publishing.service.gov.uk is an alias for www-gov-uk.map.fastly.net.If I could edit my original comment to give precedence to the original report link, I would!
it's the main website for the UK government, not sure if mistaken or a sly little dig at the UK.
If I could edit my original comment to give precedence to the original report link, I would!
Having worked with several autopilots in sims, they are extraordinarily user UNfriendly and unnecessarily complicated.
But, aviation is extremely conservative (and rightly so) and as such, changes and improvements are very small and incremental.
But then, I learned driving with stick, not automatic. I am a representative of your "give me more control" group. Even in other things, I find that there are a lot of automated systems around that do nothing for me because they don't quite behave as I would like and I have not enough control over them to adjust them. The more advanced mu knowledge in a certain area is, the more control I would like to have over related devices.
Low-power automatics (like the one I rented a couple of weeks ago) can be constantly shifting up and down on long up-grades, unless you lock them in a lower gear.
https://www.theglobeandmail.com/globe-drive/culture/commutin...
The pilot almost immediately did the right thing and disengaged the autopilot, recovered. They then re-engaged the autopilot and the same problem happened again (but with less loss of altitude). Only then did they set the autopilot correctly.
Similar incorrect settings had happened to three prior flights although in one of these the pilot spotted the problem before engaging the autopilot.
Source: My partner is ex-cabin crew.
Of course, we don’t know if there were other systems to prevent this. But if there weren’t, and it was truly a situation of “if the pilot reacts 10 seconds slower here, everyone dies”, then they should likely put more sanity checks into the autopilot system.
It's odd, you'd think that the sensation of dropping 500ft (152m) in 18 seconds would have alerted him, especially after take off. It's hard to visualise what that would feel like.
Just goes to show that we still don't really know if we should "trust the plane" or "trust the pilot".
If you read the UK Government report that is not what happened. The plane was at 1500 ft when it began to descend. At 1300 ft the warning sounds activated and the pilot reacted but it took another 300 ft of descent before the pilot was able to fully recover from the descent.
A good safety check here would be to not record an altitude if the plane’s airspeed is moving less than some value (or perhaps better, if AoA is above the critical limit as the wing is stalled).
It's possible the pilot should have refrained from engaging the autopilot during initial climbout. Pilot workload is high at that point in a flight, and fiddling with gadgets is distracting. Maybe wait until passing through 5,000 feet?
By all means, the pilot/crew needs to be monitoring things and always ready to hand-fly the airplane without automation, but proper use of automation is safety-enhancing. When the automation fails, go down in level of automation and hand-fly if needed. Good presentation on the topic from an American Airlines training session: https://www.youtube.com/watch?v=pN41LvuSz10
Sounds like they were waiting on the ground and had time.
One of the preflight checks is that the autopilot is disengaged for takeoff, but we did this after the checklist.
We took off with the autopilot set to something like 4000ft, making it want to climb at an impossible rate of climb. As a novice pilot it took me several seconds of fighting the controls to figure out what had happened, all the while with the stall horn blaring on takeoff. Scary lesson.
I used to fly and during my license test we did get into a stalling exercise to force the plane to stall at a few thousand feet altitude. This was meant to learn the feeling of sudden drop and how to recover. There is something both thrilling and scary about transitioning so quickly from seeing the horizon to seeing only earth right in front of you approaching at a high rate of speed.
Being in near-stall conditions close to the ground seems to me like a recipe for disaster.
I wonder if that is one of the amendments.