Two Cathay Pacific captains lose eyesight during flights | Hacker News Reader

Two Cathay Pacific captains lose eyesight during flights

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100 pointsturtlegrids63 comments

Three factors to keep in mind:

Pilots, especially international pilots, sit for extremely long periods of time, which is inherently bad for vascular health and makes it difficult to get even the minimal exercise that even office workers get by walking around.

Shortness of breath and blurred vision are common symptoms of heart arrythmias and other heart conditions.

Cathay Pacific is the world's largest cargo airline and the world's tenth largest airline in terms of sales, so they employ a lot of pilots.

It's also all of two guys, could happen to a small airline... still just two guys. Hard to measure significance.

Yeah, could this be an example of the law of truly large numbers?

https://en.m.wikipedia.org/wiki/Law_of_truly_large_numbers

Makes me think about fume events:

http://avherald.com/h?article=4b6eb830&opt=1024

At a claimed 2,000 events per year, find it a little disturbing that there aren't requirements to monitor air bleed.

A lot of the fume events are reported by Lufthansa [1].

I strongly suspect that that's not because Lufthansa has more fume events than other airlines, but because they are more scrupulous about reporting them. Thus, 5 events per day might not be implausible. It does seem about time to do something about that.

Personally, I'm not a fan of the 787 Dreamliner, but there might be something to the idea of replacing bleed air by a better alternative.

[1] http://avherald.com/h?search_term=fumes&opt=0&dosearch=1&sea...

EDIT: that ^ search originally only included accidents (missing mere incidents)

I've done work in this area. It's really hard to monitor the bleed air because the required equipment is very expensive and degrades fairly rapidly over time due to contamination from random stuff. For example, when you sit behind another airliner waiting, the engine ingests exhaust and that causes lots of (mostly harmless) stuff to enter the bleed air which you then need to worry about getting in your sensor.

Maybe this is a hint that aircraft that are behind other aircraft should recirculate their cabin air instead of adding outside air until they’re somewhere less stinky.

I'm willing to bet that would be worse. Try to visualize the amount of air volume per passenger on a fully loaded A321. More than a few minutes of that would probably make the cabin unbearably stuffy.

Probably about 5cfm/person + 0.12cfm/sqft based on typical ASHRAE Standard 62.1 numbers.

Although they don't have "Airliner Cabin" as a space type, my guess is based on sedentary 1met people and a rather high VOC load from the amount of luggage and upholstery is in an Airliner Cabin. Might be higher on the cfm/sqft.

I find that page kind of dubious at best, given the substantial number of factual assertions without sources, the conveniently unavailable video, the entirely anonymous letter cited as a source, and the basic fact that even the very existence of "aerotoxic syndrome" has been rejected by inquiries and studies in several countries[1][2].

[1]: http://www.asma.org/asma/media/asma/Travel-Publications/Cabi...

[2]: https://publications.parliament.uk/pa/ld199900/ldselect/ldsc...

Edit: The "evidence" on that page is the existence of pilots who died prematurely of heart conditions and suicides, an anonymous letter scanned from a self-published book, a conveniently unavailable video, a bunch of slides without citations, the presumption that a lack of official information about a supposed previous event (which has all the same hallmarks of non-proof) is proof of a nefarious conspiracy, and a death report that mentions acute myocardial infarction and lethal levels of opioids from which we're somehow supposed to conclude that the actual cause of death was an airborne neurotoxin inhaled 50 days before.

Ok but "fume events" are reported all the time; I'm not sure what exactly you're disputing. Maybe it sounds conspiracy-theory like to you, that there is this not often discussed risk in flying due to supplying cabin air from the jet engine directly, but the FAA has recently shown that their corporate relations trump public safety, and there are clearly major financial interests to downplay the risk and keep out of the mainstream. Folks should use their own judgment.

The existence of fume events, and the basic health concerns that come with being exposed to jet fumes or aerated oil, are not a conspiracy theory. The idea that fume events are somehow linked to mass exposure to a neurotoxin that the FAA and every other major government are suppressing information about is a conspiracy theory.

> The idea that fume events are somehow linked to mass exposure to a neurotoxin that the FAA and every other major government are suppressing information about is a conspiracy theory.

Alternatively, there is no conspiracy, and every major government simply ignores dangers of aviation jet fumes. Sort of how everyone was sure, that invisible radiation is near-harmless and that radium dials are safe to use, until suddenly they weren't.

Well yes, but when it's a safety obsessed industry that's conducted studies into neurotoxins and cabin air is the subject of debates by national Parliaments, there's also the possibility that the internet theorist with no medical training might be being ignored because he's wrong. (the Mulder paper is, admittedly, considerably more substantial, although it's also a study of a single deceased individual)

https://www.aviation24.be/airlines/study-reveals-permanent-b...

This is terrifying.

The two incidents were about four weeks apart.

Would anyone here happen to have information on the base rate of commercial airliners issuing a pan-pan due to one pilot becoming incapacitated?

Don't know where to find numbers, but searching AvHerald could give you some qualitative feel for it. Definitely happens quite a bit (no wonder, given how many flights there are per day).

http://avherald.com/h?search_term=incapacitated&opt=0&dosear...

EDIT to add: fortunately, p^2 is quite small for small p. And apparently there are rules in place to prevent both pilots having the fish for dinner.

https://aviation.stackexchange.com/questions/555/is-it-true-...

http://www.traveller.com.au/why-pilots-dont-eat-the-same-mea...

EDIT 2: "More recently, a 2010 Civil Aviation Authority report suggested that between 30 and 50 pilots, operating flights to or from a UK airport, are incapacitated at the controls every year – many because of food poisoning."

(from the last link above)

Seems like it's frequently enough (and my assumption is that flights with different crews are generally pretty independent, and largely independent of airline) that "two incidents on one airline in one month" isn't a glaring-alarm-raising-unlikely event.

PAN-PAN (urgency) is more common in other countries. In the US, pilots typically "declare an emergency" which can be anything from a engine caution message, to a critical emergency, which would justify a MAYDAY call. Sometimes, pilots will upgrade a PAN-PAN to a MAYDAY if their situation gets worse.

One reason for US pilots to only declare an emergency, and not "urgency" is when a pilot requests priority, FAA procedures sometime require Air Traffic Controllers to treat a priority or urgency as an emergency, even if the pilot does not expressly declare the emergency.

Almost all airliners require 2 pilots. Unless they have a relief Captain, or fully qualified jumpseat pilot, they have to declare PAN-PAN (urgency) or emergency, when flown by a single rated pilot. The chief flight attendant (pursor) may assist in the cockpit, and frequently does sit in the cockpit seat, when either pilot uses the bathroom.

Are passengers at risk from the fumes that are causing pilots to pass out in the cockpit and then die? Are these chemicals present in automotive oils?

Fume events usually mean burning turbine oil which releases a very potent neurotoxin. The smell is usually described as being like wet dirty socks. It's not unusual to smell things in the cabin during taxi though as the bleed air will contain some jet exhaust which is harmless.

https://en.wikipedia.org/wiki/Tricresyl_phosphate

The idea of "fumes that are causing pilots to pass out in the cockpit and then die" (supposedly "aerotoxic syndrome") has been rejected by inquiries and studies in several countries[1][2].

[1]: http://www.asma.org/asma/media/asma/Travel-Publications/Cabi...

[2]: https://publications.parliament.uk/pa/ld199900/ldselect/ldsc...

Apparently the studies were industry-funded. It would be nice to see an independent study because the chemicals at hand are known to be neurotoxic and they also have those symptoms.

Of the studies noted in my first link, two were funded by charitable nonprofits, three were funded by government agencies, and none were funded by the airline industry.

There's no mention of fumes being the cause of these incidents in the article.

Where does the article mention the pilots dying?

Not this article but this has happened

http://avherald.com/h?article=4b6eb830&opt=1024

That page is hardly a reliable source, given that its "evidence" is the existence of pilots who died prematurely of heart conditions and suicides, an anonymous letter scanned from a self-published book, a conveniently unavailable video, a bunch of slides without citations, the presumption that a lack of official information about a supposed previous event (which has all the same hallmarks of non-proof) is proof of a nefarious conspiracy, and a death report that mentions acute myocardial infarction and lethal levels of opioids from which we're somehow supposed to conclude that the actual cause of death was an airborne neurotoxin inhaled 50 days before.

It was officially ruled to be a result of the fume event...

It was officially ruled as "undetermined"...

"Undetermined" with lethal blood levels of opioids and acute myocardial infarction sounds to me a lot more like "either the heart attack or the overdose killed him, I'm not sure which" than it does "actually, he died from neurotoxins he was exposed to 50 days before which I conveniently left out of the death report". The only source used to even claim the connection is a doctor whose major paper on the subject tries to call itself "significant" despite having obviously non-significant p-values.

[1]: http://bleedfree.eu/wp-content/uploads/2015/10/Cognitive-imp...

NB: A single flight would have a Captain and a First Officer. Therefore, this is about two Captains on two different flights.

Should have been obvious to me on headline reading, wasn't, alarm ensued.

"A lower flight level to decrease the cabin pressure altitude was also requested to assist with the captain’s recovery."

Doesn't flying lower make the cabin pressure increase?

Pressure altitude, they describe cabin pressure in terms of apparent altitude, usually 8000ft+/- and by lowering the outside altitude they can increase the internal pressure/decrease apparent altitude.

I see what you are saying and the article's sentence is technically not wrong. But it is a useless phrasing none the less. By decreasing altitude they decrease apparent altitude... so what? How is that different than saying by filling a glass with water I increase apparent fill level...

This is a medical situation so what is relevant is how the change effects the body. So I think the most clear thing to say is that... they flew lower to increase the cabin pressure. Maybe it is some thoughtless force of habit that they chose to describe it that way.

Pressure altitude isn't the same as flight altitude. You can decrease flight altitude dramatically without changing cabin pressure altitude. You can also vary cabin pressure altitude without changing flight altitude. So saying they descended to lower the cabin pressure altitude is not useless. It describes the outcome (lower cabin pressure altitude) and how they achieved it (by descending). There are other ways of changing cabin pressure altitude, and there are reasons to descend other than for the purpose of lowering cabin pressure altitude.

Edit: I see the "I don't understand this so it must be bad" reaction in a lot of junior devs. It's interesting to see it show up in other areas!

There is value in adding a concise, incorrect comment on hacker news if it is presented in a clear and falsifiable way. I am sorry I did not google "pressure altitude" before commenting and did not present my findings so others could learn from it, but I am happy that AWildC182 cleared it up for me.

I still think that the sentence in the article could be written in a clearer, and more direct and correct manner -- that is I think it is bad for reasons other than me not understanding the definition.

I understand that pressure altitude is a way to express pressure using a theoretical equivalent altitude, and that it is widely used in aviation because it is convenient and tangible way to express pressure!

Though, I still think the goal was to increase pressure (measured in Atmospheres) on the person undergoing a medical emergency. There would be almost no point for a space pilot to descend from 70 to 65 miles altitude in contrast to a terrestrial pilot descending from 8 miles to 3 miles. Even though the difference is pressure altitudes is the same (5 miles delta), the difference in Atmospheres is hugely different. (In the space case there is almost no difference because there is almost no pressure!) That indicates that the patient requires an increase is pressure (Atmospheres) So why not write "They descended to increase cabin pressure". It's simpler, more direct, and shorter.

It's offensive to couch a personal insult as an "interesting observation" about junior devs' failings showing up in other areas. Your whole comment seems to be made in bad faith and attempts frame me as a fool to be laughed at. This is one of the reasons I sometimes hate participating in hacker news. Even if I'm an idiot I don't think the snark is justified.

You initially expressed confusion about the difference between altitude and pressure altitude with your question "Doesn't flying lower make the cabin pressure increase?"

When AWildC182 pointed out your mistake you insisted that the sentence was useless because it was confusing to you. The sentence seems useless to you because you don't have the depth of knowledge to understand it, and instead of putting forth the effort to understand you throw up your hands and declare it a bad sentence.

That pattern happens all the time in software with junior developers. They come in so sure of their abilities that anything they don't understand must be wrong or bad or useless. Your exchange here was the first time I had seen it happen outside of software development and I thought it was interesting, so I commented on it. If you find it insulting to have that behavior pointed out to you I would suggest avoiding the behavior.

You got two pieces of advice for the price of one. In your place, I'd be thankful. No one will remember your username on the internet. I haven't even seen it. Unlike real life, any feeling of humiliation can easily be ignored.

Yea, the article was a little strange. They were trying to use the technical aviation terminology as much as possible but ended up mixing and matching a bit after apparently realizing explaining all of it would make the article really long.

I had to read that sentence a dozen times to figure out what they were saying. It's probably the first time I've ever seen the phrase "Cabin Pressure Altitude" - Might make sense in a technical aviation document, but I'm guessing 99% of readers would have had an easier time with "A lower flight level to increase cabin pressure."

The terminology works very well for pilots, because pilots have got it locked into their brain that higher altitude == lower pressure. Pilots also have fairly extensive rules for how and when they can fly at a given "altitude", defined in terms of the atmosphere the pilot is breathing, so it makes sense to think of the cabin's pressure as "altitude". "Pressure" is not something you can really feel beyond the extremes, but altitude is something you really understand every second of every flight.

If you're a pilot.

Pilots are also naturally going to parse that as (cabin (pressure altitude)) rather than (cabin pressure) altitude [or any other grouping].

Even as a non-pilot, 8,000ft is more intuitively meaningful than 10.88psi or 0.74atm.

8000' is pretty comfortable from an air pressure perspective. In practice, I'll do 9,500' or so for longer durations in an unpressurized plane in the daytime. Lower at night unpressurized. Wonder if the event was at night.

Flying (as pilot), you require supplemental O2 if you are over 12,500' pressure for 30 min, 14,000 it is a must. Seeing them set the internal pressure to half of the 'you must wear a mask' levels makes sense.

As a structural engineer, I feel like it'd be "obvious" to default to megapascals (MPa) here. Maybe it's less relevant for planes, but if you're in, say, a submarine, then there's a direct relevance of the pressure of the air inside the sub, the pressure of the water outside the sub, and the tensile strength of the hull of the sub—and they're all measured in MPa (or sometimes GPa.)

For airliners altitude pressure isn't structural (any more) beyond tracking pressurization cycles. It's much more about the human factors; passenger comfort (and sometimes injuries such as burst ear drums), and the aeromedical factors of oxygen saturation within the pilots' bloodstreams.

TIL about the medical certificate system for pilots. I guess I figured there must have been something in place, didn't realize it was a tiered system.

That article might lead a reader towards a wrong conclusion. A first-class medical is required for all air carrier operations. (That they bothered to report that both pilots had a "class 1" medical would be seen as odd to anyone in aviation.)

In rough terms, second-class medicals are good for commercial but not air-carrier operations, and third-class medicals (or now, BasicMed) for private aviation.

HN seems to be on an aviation accident kick. Interesting to see how long this trend lasts. There haven't been more events on this impact, they've just been surfacing to the front page more frequently following 737 MAX stores.

Probably because the 737 issues were software related. And the trend of airline news is just up in general because of that whole ordeal. News outlets make articles of things that are currently relevant.

It’ll probably slow down soon.

Is there any possibility of an infrared laser attack?

From where?

Indeed. Inverse square law would make that a) low-altitude event, or b) high-power beam.

No, not really. You can easily blind people far away with lasers.

That depends of "far away" - good luck trying to aim at something at FL 350, yet it's only some ten clicks away from you.

From anywhere close by?

Two? They were probably caused by a conspiracy theory. I've heard there's a lot of those going around the days.

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