Comment by squidi | Hacker News Reader

Comment by squidi | Hacker News Reader

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I think it's an oversimplification to say the reason for this innovation not happening sooner is because of risk. The Boeing 777 flies on only 2 engines which sounds far riskier but didn't stop it being approved. Also there's a race for building planes from carbon materials.

Robert Witwer, vice-president of advanced technology at Honey-well of Morristown, cited some other reasons [1]:

- Increased congestion: "Short hauls do a lot of taxiing time, especially in a place like Newark, where you can be 20th in line"

- Legislation: “And there are a number of airports in Europe that have tough emission standards that would make the Green Taxiing System appealing. I believe it’s a game-changing technology."

- Fuel costs: "The prospect of annual savings of $200,000 per jet from lower fuel use and less ground time has sparked interest from Airbus and airlines such as EasyJet and Alitalia. Airlines face the highest sustained prices ever for jet fuel. United Continental, the world’s biggest carrier, says it burns $25,000 of fuel per minute. Jet fuel delivery in New York averaged $3.12 per gallon in 2012, more than four times as much as a decade ago."

- Technological advances: "What’s new in today’s technology is the convergence of airlines’ search for more efficiency and recent advances in miniaturizing electric motors to propel a plane at the 32 kilometres per hour it may need for taxiing."

[1] http://www.wingsmagazine.com/index.php?option=com_content&ta...

It sounds risky to operate with only 2 engines, and in 1953 twin engine planes were only allowed to be within 60 minutes of a diversion airport, mostly because of the unreliability of piston engines. It was a fairly long journey to allow twin engine planes to fly the kinds of routes they are allowed today. http://en.wikipedia.org/wiki/ETOPS

As jet engines turned out be much more reliable than their piston counterparts, the restrictions were loosened over time, starting with waiving the 60 minute rule for tri-jets in 1964. The original concept for the 777 was actually a tri-jet design. However the 767 turned out to be very reliable as a twin-engine plane and in 1985 it became the first twin engine plane to be allowed to fly 120 minutes away from a diversion airport (ETOPS-120) and in 1989 it was allowed to fly 180 minutes away from a diversion airport (but planes had to first complete 1 year with 120 minutes before they could be certified for ETOPS-180). Since twin engine designes were suddenly much more capable than anticipated Boeing dropped the tri-jet design of the 777, and eventually came back with a twin-engine design. By 1995 there was enough experience with operating twin engine planes with the 180 minute rule in place and Boeing was able to get the 777 certified to 180 minutes from the start.

So it basically took from 1953 to 1995 to allow a brand new twin-engine plane to fly most transoceanic routes (with a 180 minute rule in place), based on increasing evidence that the jet engines themselves are fairly safe, and learning more about additional safety mechanisms and procedures required to safely operate twin engine planes at extended distances from diversion airports.

Great post, thank you.

It's more like risk vs gain. There was a lot of testing and previous experience leading up to the 777 launch ETOPS rating. A better example is the 787 battery system. Likewise, you want to be very certain that the new electrical motor system won't interfere with normal braking, so something that sounds simple becomes very complex and difficult once you put it on an airlplane.

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