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Comment by wkat4242 | Hacker News Reader

But the 4-engined models can fly more direct routes over oceans and uninhabited areas right? Because of ETOPS. Of course this is not a problem on many routes.

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ETOPS is what allows twins to fly routes that would otherwise require trijets or four engines. I'm not sure what the limits are but flights to Hawaii for example are routinely done with twins.

I know, but as far as I know it requires them to stay with 200nm or so of an airport. So they can't take the most direct route. Also for flights over the poles.

I think four engines still have a benefit there. But I guess you don't run a whole airplane model just because it's not economical on 2 or 3 routes.

I have personally flown from Seattle to Hawaii on a 737 MAX. That is 2320nmi. So no, the ETOPS limit is not 200nmi. There's nothing between the west coast and Hawaii but water. You can see AS853 is a nearly straight line from Seattle to Honolulu. If any of that deviation is for ETOPS it is minor.

ETOPS is time based, not distance based. The 777 has been approved by the FAA for ETOPS-330, which is 330 minutes of flight time to the nearest airport on one engine.

The 737 MAX is ETOPS-180, so it only has to be within 3 hours of a suitable airport when running on one engine.

https://flightaware.com/live/airport_status_bigmap.rvt?airpo...

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

https://en.wikipedia.org/wiki/Boeing_737_MAX

https://www.flightradar24.com/data/flights/as853#2ef8bfcb

The 787 has a 330 minute ETOPS certification, so as long as it’s within 6.5 hours of an airport it can fly there.

That’s almost everywhere on the planet except the South Pacific and Antarctica.

Aha ok, I didn't know that. I thought they had to remain within glide distance (and I think this was also the case in the beginning). I haven't flown intercontinentally for a very long time :) And most of it was in 747s.

Glide distance was never a consideration of ETOPS.

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