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Comment by sagarun | Hacker News Reader

I still remember they used disinsect the aircraft cabin, before you land in Indian airports with an aerosol spray https://www.transportation.gov/airconsumer/spray

https://www.epa.gov/mosquitocontrol/aircraft-disinsection

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They still do this when you land in Australia

Not in my experience. I have only flown international ten times or so in the past 20yrs but I have never seen that when returning to Aus.

Every plane is. https://www.agriculture.gov.au/biosecurity-trade/aircraft-ve...

Probably depends on where the plane is coming from. Source: me who just returned from Europe last week, no spraying. And have traveled internationally several times in the last few years and also no spraying.

From the link:

"Benefits of entering a voluntary formal arrangement include:

* disinsection methods are undertaken while passengers are not on the aircraft."

Used to see someone wandering down the aisles with spray cans on arrival - but not on the last several trips to Oz.

I was interested in this because it happened the last time I returned to NZ, but I hadn't seen it before. There are several approved methods and it depends on the airline. The method that doesn't involve spraying with you onboard is more expensive so tends to be used by budget airlines, and also airlines who might rotate their planes and crew around routes more often because it is a treatment that lasts for weeks.

They did that on our take off from Naples just a month ago, they said it's against insects.

They do but chances are it's not 100% effective.

Rather, "there is no evidence to show that using insecticide to kill mosquitoes inside aircraft cabins is effective in preventing introduction and spread of mosquito-borne diseases."

https://www.epa.gov/mosquitocontrol/aircraft-disinsection

Not sure where the idea came from that spraying the cabin aisle would penetrate the luggage bins, cargo hold, under the seats, or really anywhere.

1. Absence of evidence is not evidence of absence.

2. Risk is convex, so every risk increase by measures not taken is multiplicative, not additive.

The real question must be: does the disinfection do more harm than it provides reduction of risk.

> 2. Risk is convex, so every risk increase by measures not taken is multiplicative, not additive.

Wait. Is this true? f(x) = x^2 is convex but f(x+d) = f(x) + O(x). Are you saying that human risk assessment is estimated to be exponential?

It used to happen in NZ too. I don't know if it still does.

As a kid (in the early 70s) I remember the air hostesses walking down the isles with a spray can. They don’t do that any more, but I wonder if or why they don’t add lower concentrations of the aerosol to the air conditioning at the end of the flight.

You could spend tens or hundreds of millions building an automatic system (certification for aircraft is not cheap or easy) or just hand the flight attendant a can of spray.

Sure, but I can imagine the more expensive airlines worrying that the ‘optics’ of spraying your passengers down aren’t great (to be clear - I’m not objecting and I’d rather they do it). I wasn’t suggesting they retrofit to existing aircraft of the period, but rather just build it in as they design the next generation airflow system. Or do you think it would still be way too expensive even then?

Adding systems to aircraft, whether retrofit or new design, is a horrifically complex and expensive thing.

What kind of disinfectant is used? How is it distributed? Does it do something bad at -80 degrees C? At +80 C? If it freezes, what happens? What if someone loads the wrong thing into the disinfectant bucket? Like fuel? Or oil? Where do we put the switch to isolate the cockpit from the disinfectant? Where does flipping that isolation switch go in the unknown-fume-event checklist?

What if it catches fire? It's not enough to say it can't catch fire, you must assume it will catch fire. The fire suppression system has to be aware of it. What if the fire suppression system erroneously thinks the disinfectant system is on fire? What if it was erroneously thought to be on fire, and then later _actually does catch fire_? How long can we fly with a flaming disinfectant system that someone in Terribadistan filled with kerosene?

You probably have more than one disinfectant module, probably attached to each pack. Is the plane "disinfected" if only one pack is operational? If your disinfectant module fails, does it bring the pack down with it? No? Now we have to certify the packs for both with-and-without disinfectant module operation.

Cockpit announcement: "The authorities here require us to have flight crew spray for mosquitos upon landing using aerosol cans before opening cabin doors. you will now see the attendants walk down the aisle spraying so we can unload you as soon as possible."

It would still be expensive for next gen too. Having to design an entire system that has never existed before that can operate under aerospace conditions is expensive as hell even before you get into certification. A sibling comment points out all of the design certification issues you need to think about

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