Comment by arcticbull | Hacker News Reader

Comment by arcticbull | Hacker News Reader

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150,000 flights, 172 seats per is 25.8 million passenger seat-journeys. Given the type, I think it's fair to say they're at least 1200mi long (why fly a 7M8 on a sub-2 hour flight, when you can just throw a regional jet at it). The whole point of the MAX family is that it can fly further than a normal variant. This is 30.96 billion passenger seat-miles. There were ~350 deaths. This is 0.000000011 deaths per passenger seat-mile, or 11 per billion. This is in line with but still less than driving (12.5 per your data source).

I imagine 1200 miles is short for an average 7M8 flight though, which could make it substantially safer. With 2500 mile averages you get back to that 3X number I cited. It's still no more a death trap than your average Honda Civic (10% safer by your metrics, more by mine).

To your point, it is of course riskier than a different aircraft.

My whole thesis was to ask what effect this will have across the entire population and how will humans react, irrationally, to this news.

There are arguments against measuring crash rates by “number per vehicle miles traveled” and instead by “number per vehicle hours traveled.” VMT is a product of speed and time, and thus a fatalities-per-VMT metric will nearly always show the faster routes to be safer.

But compare spending 20 minutes traveling 10 miles on a local street, vs 10 minutes traveling 10 miles on a freeway. Both are considered equally safe using a fatalities-per-VMT model. But in the former, you’ve stayed safe for a longer portion of your life. (See http://pedshed.net/?p=1050)

Using that metric would make that Boeing far less safe compared with driving.

But you travel to get somewhere not to be in a vehicle for X amount of time. So why would any metrics besides per-distance be more relevant.

As a traveler, I care about the trip, not the time nor the distance. If I take this trip, what's my probability of dying if I fly it versus drive it.

Airplane travel have fixed segments (takeoff and landing, ascent, descent) and variable segments (the coasting phase that varies by distance traveled). Car travel is only the variable segment. Hard to compare apples to oranges.

> measuring crash rates by “number per vehicle miles traveled” and instead by “number per vehicle hours traveled.”

there's another issue, which is plane risk is uneven during their journey, so a type that does half the flights but twice the distance on average will end up almost 1.5 times as safe all other things being equal.

this source claim 45% crashes happening on takeoff and landing which are a minimal percentage of travel if you measure risk by mile or hour: https://eu.usatoday.com/story/travel/columnist/cox/2013/08/2...

a way to normalize that would have to use "number per flights" but then you'd get trains, with their multi-stop journeys, skewing the numbers the other way.

That argument seems flawed to the point of absurdity. Two extreme examples showcase this:

1) a teleporter with the exact same risk as driving 20min on local streets or 10min on the highway would be the worst thing ever invented. In reality, 100% of people would choose it unless they were intentionally wanting to spend time driving

2) A 100% safe ridable snail would be the ideal form of transit, given that you'd spend your whole life safely trying to get somewhere.

On the flip side, if the plane is intended for long flights, do you think people are just going to drive 1200+ miles and incur the gas, the additional time, a hotel stay or a few?

Some trips may be made using older aircraft. Some trips may not be made at all. But I think assuming a 1:1 correlation with driving is a bit silly.

A very good point, although, my fear wasn't that people would replace 1:1 7M8 flights with a roadtrip across the country, but that grounding an entire plane type would cause people to replace short flights with long drives. I suppose planes falling out of the sky may do that too :)

Fatalities per passenger mile is a good metric for passengers, but for the FAA, I think crashes per vehicle mile is a better target.

That is, the plane isn't inherently 100x safer if you just fly it empty.

Yes, the plane is much safer if you fly it empty.

It's still a risk to those on the ground!

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