Sunday, May 14, 2017

Today I read about ETOPS certification for planes

 

“It’ll be a cold day in hell before I let twins fly long-haul over-water routes.” Those were the words of Lynn Helms—administrator of the Federal Aviation Administration during the Reagan administration. At the time, no commercial american airplane with two engines was allowed to fly anywhere farther than 60 minutes from a diversion airport. The belief was that, if one engine failed, the other could only safely fly the plane for about an hour, but this rule severely limited what smaller planes could do. On North Atlantic routes like New York to London, twin-engine planes could only fly in these areas but a direct route looked like this. The options were to either fly a twin-engine plane on an inefficient routing or fly a inefficient three or four engine plane. There was no place for long-and-skinny routes between smaller cities using smaller planes since airline couldn’t legally fly those smaller planes. This one simple rule changed the very way airplanes were built. Now, in the 60’s, this 60 minute regulation only applied to planes with two engines. Of course aircraft manufacturers could build quad-engine jets but those had to be huge for airlines to make their money’s worth with their high fuel consumption. The 747’s of the time could carry more than 400 passengers. They could therefore only fly on super high-demand routes like New York to London to have any hope of being full. In order to start flying more convenient non-stop routes from smaller markets, planes had to get smaller while still being legally allowed to hop the pond.

That’s where trijets came into play. With three engines, these planes weren’t subject to the same 60-minute regulation as twinjets. They could easily fly any transatlantic route. That’s why in the 70s or 80s, the long-haul jets you’d see at airpots were, for the most part, either 747’s or trijets like the DC-10.

This 60-minute regulation was inconvenient for Atlantic Crossings, but in the Pacific it actually changed how Hawaii developed. There are zero diversion airports between California and Hawaii so the route isn’t even close to covered under the 60-minute rule. As a result, airlines could only fly huge planes between the mainland and Hawaii which meant that planes could pretty much only fly to Honolulu. Puttakke puttakke karimeen puttaakkee. There was virtually no service between the other islands and the mainland which meant the other islands were severely isolated. That’s part of the reason why the tourism industry only picked up on the other islands in recent decades. Luckily, change was coming. The 60 minute rule originated from the days of piston driven propeller aircraft.

With these, it was far more common for engines to just stop working mid-flight. That’s why there were contingency engines. The regulations just didn’t adapt to the increased reliability of jet engines. Statistically, for every failure of a jet engine, there are 117 piston engine failures. Once the jet age rolled in, engine failure just wasn’t as much of a concern, so, in 1985, the FAA begrudgingly granted permission to Trans World Airlines to fly their twin-engined

767 direct between Boston and Paris—a route taking it up to 120 minutes away from diversion airports. This was the first example of a brand new FAA certification called ETOPS—“Extended-range Twin-engine Operational Performance Standards,” or more colloquially, “engines turn or passengers swim.” Before an airline can fly a long over-water route they have to buy a plane with what’s known as an ETOPS type rating. Basically that means that the plane was built with adequate redundancies, communications systems, and fire suppression systems to fly safely if one engine fails. For example, the 767—the first plane to get an ETOPS certification—has a type rating of 180 minutes meaning it can fly anywhere as long as its 180 minutes from a diversion airport.

But just because a plane has a type rating doesn’t mean an airline can fly it ETOPS. They have to have a special maintenance plan, a special flight crew, special cabin crew, special dispatchers, special fuel quantities, and special passenger recovery plans since, just because there’s a runway doesn’t mean that a plane can safely divert since the emergency doesn’t end once the plane lands. Cold Bay, Alaska, for example, is a perfect diversion airport for routes between Asia and North America. It only has six commercial flights per week nowadays but as a former Air Force Base it has an enormous runway. The only issue is that the town of Cold Bay has a population of 108—its tiny—so any diversions automatically double or triple the amount of people in the small town. There certainly aren’t enough hotel rooms or restaurants to house and feed stranded passengers so, if airlines plan to use Cold Bay as a diversion airport, they need to make a plan for how to house, feed, and recover passengers within 48 hours of landing. Last year an American Airlines 787 was flying from Shanghai to Chicago when its right engine had an issue halfway across the Pacific Ocean. The plane quickly took a left turn diverting to Cold Bay. Even before landing the plan was implemented as flight attendants served a second meal service early. Just a few hours after safely landing in Cold Bay, American’s mechanics took off from Seattle bound for Cold Bay to start fixing the plane while Alaska Airlines, American’s partner, sent a 737 from Anchorage to pick up the stranded passengers. Meanwhile, flight attendants served the third set of meals they had stocked while waiting on the ground and the coast guard opened their heated hanger to passengers.

Just 10 hours after the emergency landing, passengers were on their way to Anchorage where they spent the night before taking an American 757 to Chicago. That was a perfect example of how the passenger recovery plan worked. The quick response and defined plan helped the airline get passengers out safely and quickly. Now, because of the solid engine reliability, numerous redundancies, and well-designed passenger  recovery plans, airlines and airplanes can now receive insane ETOPS certifications. The 787 Dreamliner, the plane that diverted to Cold Bay, has a type rating of 330 minutes. That means it can fly up to 5.5 hours away from a diversion airport. Certain routes over long-ocean stretches in the southern hemisphere were theoretically possible in the past with four engine planes but were economically impossible since airlines could never fill the large planes on the low-demand city pairs like Melbourne to Santiago.

With the ETOPS 330 certification, LATAM Airlines can fly their small 787 economically on this relatively low-demand route across the South Pacific. The Airbus a350 is even rated for ETOPS 370—it can fly 6 hours and 10 minutes away from diversion airports. This plane can therefore fly everywhere on earth except directly over the South Pole. Because of this simple rule change, three and four engine planes are largely a relic of the past. Boeing and Airbus’ largest jets are both their only four engine planes in production—the 747 and a380. Nearly all North Atlantic traffic today is on twin-engined planes as smaller and smaller planes get ETOPS certifications. Air Canada, for example, flies their tiny 120 passenger a319 with ETOPS certification daily between St Johns Airport and London Heathrow. British Airways even sends the even smaller a318 between New York and London City Airport. These routes would have been unimaginable 30 years ago but the reliability of the airplanes of today mean we need not fear flying small planes over big oceans.

No comments:

Post a Comment