Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Preliminary report into Air India crash released

bbc.co.uk

Post reply on HN
Print view View original

831–840 of 924 posts

Re: Preliminary report into Air India crash released

#831

Post by terom »

wkat4242 wrote: post #584
xeonmc wrote: post #467

Earlier quoted context omitted.

Here's another one: Air Canada 143 - Pilot calculated incorrect fuel due to metric/imperial unit mixup, and ran out of fuel midair. - Said pilot performed an impossible glider-sideslip maneuver to rapidly bleed airspeed just-in-time for an emergency landing at an abandoned airfield, having to completely rely on eyeballing the approach. - No fatalties or serious injuries. https://www.youtube.com/watch?v=jVvt7hP5a-0

It's not an impossible maneuver. Glider pilots do this all the time especially if they don't have spoilers

Also with additional control difficulty due to reduced hydraulic pressure.

> On the Boeing 767, the control surfaces are so large that the pilots cannot move them with muscle power alone. Instead, hydraulic systems are used to multiply the forces applied by the pilots. Since the engines supply power for the hydraulic systems, in the case of a complete power outage, the aircraft was designed with a ram air turbine that swings out from a compartment located beneath the bottom of the 767,[10] and drives a hydraulic pump to supply power to hydraulic systems.

> As the aircraft slowed on approach to landing, the reduced power generated by the ram air turbine rendered the aircraft increasingly difficult to control.[16]

> The forward slip disrupted airflow past the ram air turbine, which decreased the hydraulic power available; the pilots were surprised to find the aircraft slow to respond when straightening after the forward slip.

Re: Preliminary report into Air India crash released

#832

Post by xboxnolifes »

chii wrote: post #436
m101 wrote: post #387

What makes me more inclined to suicide is that this might have been the perfect time to do this so that even a small interruption in fuel would be catastrophic.

If this is the case, you have to then think about why this pilot would want suicide but also murder all aboard the plane. It's a bit irrational if they wanted to just suicide - you can easily just cut your own throat, hang yourself, or jump off a tall building.

It's a mistake to try to rationalize suicide. People frequently make irrational decisions.

Re: Preliminary report into Air India crash released

#833

Post by fc417fc802 »

sillysaurusx wrote: post #794
fc417fc802 wrote: post #789

Earlier quoted context omitted.

Without necessarily taking a side (I don't know enough about the specifics of the FAA policy or the various incidents over the years) I'd like to suggest that you are rather missing the point of the person you are responding to. Take your argument to the extreme. Suppose someone has a physical or mental issue that renders them unable to reliably judge a certain type of situation or undertake some action that must be…

Feeling suicidal isn’t a debilitating condition. People around you have suicidal ideation every day, and they manage their jobs well. I’ll counter your argument with this: a bus driver is allowed to feel suicidal ideation, yet they safeguard the lives of everyone on board. Maiming everyone would be as easy as accelerating on the highway and swerving off the road. Yet we don’t worry about this, because it’s rare enoug…

tl;dr We're talking about a $200 million piece of equipment. This isn't your typical job. Merely "getting by" is nowhere near sufficient.

That line of reasoning isn't an appeal to emotion but your earlier focus on dehumanization and discrimination most certainly was.

I think it's a reasonable point that such a policy exhibits a severe perverse incentive. So the question becomes, how many lives are lost due to the perverse incentive versus if the policy didn't exist? Someone with the right knowledge and resources can at least make an objective attempt at estimating that.

Regarding bus drivers I'll observe there is a stark difference in both scale and certainty of death. The degree to which safety risks are tolerated almost invariably scales with such metrics. Pilots operate in a domain where an unmitigated failure not resulting in the deaths of everyone on board is far closer to the exception than the norm.

There are also public perception and financial angles to consider. People are rather paranoid about hurtling through the air in metal tubes. The equipment is also rather capital intensive, with a 787 and a hyperscale data center falling vaguely in the same order of magnitude. As such many of the practices surrounding that activity go a bit overboard from an actuarial perspective at least in comparison to other common daily pastimes (but not in comparison to aforementioned data centers).

Which circles back around nicely to your leading statement. It is the act itself, the attempt to commit suicide, that I think is reasonable to view as a sudden and debilitating condition. Those with suicidal ideations are statistically more likely to suffer from that. I think it's extremely similar to the heart attack example, and policy certainly requires commercial pilots to have regular physicals. The primary difference (and potential point of contention) is that there's no straightforward way to hide a physical condition whereas you probably can hide a mental one and (unlike a physical one) doing so is likely to exacerbate it.

Re: Preliminary report into Air India crash released

#835

Post by ckw »

varjag wrote: post #660
tethys wrote: post #652

Earlier quoted context omitted.

> if treatment significantly reduces the probability of a pilot's committing suicide Psychotherapy significantly reduces the risk of suicide. https://pmc.ncbi.nlm.nih.gov/articles/PMC6389707/

Does it bring the risk of suicide to general population baseline? And if not would you still want the affected people be responsible for hundreds of lives?

It doesn't look like it: it says that the risk of suicide attempt for those experiencing depression decreases 37% with psychotherapy. But the baseline 12 month suicide risk is ~14/100k, while those experiencing major depressive disorder are at ~120/100k. So ~5 fold elevated risk after psychotherapy.

Re: Preliminary report into Air India crash released

#836

Post by ahartmetz »

foldr wrote: post #702
kalenx wrote: post #651

Earlier quoted context omitted.

Yes. On a plane which is designed to be a good glider. I highly doubt a 767 is designed to be a glider. It's definitely not impossible (after all, it was done successfully!), but certainly a very difficult (and undocumented) one on such a plane.

I don’t think there’s much connection between a plane’s ability to do a sideslip and how well it glides. A sideslip is just what naturally happens if you apply opposite aileron and rudder inputs. I think the issue is just that it’s a rather acrobatic maneuver to perform in a large passenger jet.

Since a sideslip increses air resistance by essentially flying sideways, if I didn't know that it has been done, I'd say it might even break apart a (long, thin) plane that wasn't designed for it. And it still might, but at much higher speeds than close to landing.

Re: Preliminary report into Air India crash released

#837

Post by tim333 »

sjsdaiuasgdia wrote: post #687
tim333 wrote: post #686

Earlier quoted context omitted.

Turning the fuel off seems roughly equivalent to turning the ignition off when you've parked your car. It's really something rather unlikely to do as a brain fart during takeoff.

Most commercial aircraft have quite a few more buttons, knobs, levers, dials, etc than a car.

They do make an effort to make it hard to do safety critical stuff by accident though in cars, small planes and jets. Like in a car it's easy to mix indicators and windscreen wipers which are on various stalks but turning off the engine and locking the steering is very different action, on traditional cars turning the key and taking it out. Similarly here the fuel cut offs are obvious levers that have to be pulled out before they can be moved.

Re: Preliminary report into Air India crash released

#838

Post by DebtDeflation »

cryptonector wrote: post #779
DebtDeflation wrote: post #733

Earlier quoted context omitted.

I'd say the odds are 50%. The odds of the opposite scenario - where the pilot who said "did you flip the fuel cutoff" wasn't the one who did it are also 50%. Based on the cutoffs for both engines being flipped 1 second apart, the above exchange being caught on the CVR, and then within 10 seconds the (presumably the other) pilot switching them back to Run, it's pretty clear that this was a deliberate act.

Reading https://news.ycombinator.com/item?id=44543536 I think we should not jump to conclusions yet.

I've been reading commentary on aviation forums like PPRuNe and the consensus amongst pilots and others in the field seems to be that "electrical glitch" is a near impossibility. Also, the report states "and immediately thereafter, the Engine 1 and Engine 2 fuel cutoff switches transitioned from RUN to CUTOFF position one after another with a time gap of 01 sec". They wouldn't have said the switches transitioned from one position to another if they weren't certain, they would have said something like a voltage change consistent with cutoff occurred. Several people have pointed out that these are large mechanical switches that make a distinctive noise when moved and the CVR is sensitive enough that it would have picked it up. Also, it's important to note that no safety bulletins were issued to Boeing as they would have in the case of some electronics issue.

Now, when I say deliberate act, I don't necessarily mean "pilot suicide" though that is certainly a strong possibility.

Re: Preliminary report into Air India crash released

#839

Post by [deleted] »

ahartmetz wrote: post #836
foldr wrote: post #702

Earlier quoted context omitted.

I don’t think there’s much connection between a plane’s ability to do a sideslip and how well it glides. A sideslip is just what naturally happens if you apply opposite aileron and rudder inputs. I think the issue is just that it’s a rather acrobatic maneuver to perform in a large passenger jet.

Since a sideslip increses air resistance by essentially flying sideways, if I didn't know that it has been done, I'd say it might even break apart a (long, thin) plane that wasn't designed for it. And it still might, but at much higher speeds than close to landing.

[deleted]

Re: Preliminary report into Air India crash released

#840

Post by panxyh »

1970-01-01 wrote: post #761
cjbprime wrote: post #721

Earlier quoted context omitted.

I don't agree with the "twice". A frequently performed manipulation like the fuel cutoff (usually performed after landing) collapses down to a single intention that is carried out by muscle memory, not two consciously selected actions.

Your opinion is valid but definitely doesn't align with any evidence.

What a shallow, copy-paste response.

His statement was about a certain, obviously real tendency in general, existence of which is reasonable to assume there is enough research about.

He objected not to the unlikelihood of an accidental manipulation, but to the potential flaw in your comparison (which was at best a valid opinion).

Post reply on HN