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On a two-engine airliner, if one engine fails, the plane can continue flying with no difficulty. But, because there is no longer an engine in reserve, regulations require the pilot to land at the nearest suitable airport. Over land, suitable airports are always nearby. What about over water?
Two-engine airliners are allowed to fly over water only if the route is reasonably close to an airport that can be used if there is an engine failure. How close is reasonable? Jet engines are so reliable that, if one engine fails, diverting to an airport several hundred miles away is considered reasonable based on demonstrated engine performance. If the idea of flying for two or three hours on one engine sounds edgy to you, that is how it sounded to pilots. During training, an instructor wrote E-T-O-P-S on the blackboard and explained it stood for Extended (overwater) Operations. A pilot raised his hand and said, "No. You've got it wrong. It stands for Engines Turn Or People Swim." Used to four engines when crossing the Atlantic, pilots weren't convinced.
But, before two-engine planes began crossing the Atlantic, engine reliability was researched on the 767s being flown in the U.S. The engines proved to be so reliable that there was not a single failure or shutdown in 2 million hours of flight. How does this level of reliability play out in ETOPS operations?
When looking at a paper map, the route between the U.S. and Europe appears to be far from land. Being flat, a paper map is a distortion. Try this on a globe; stretch a string from New York to London or Paris. The string—which falls on the shortest route—follows the coast of Canada to its northeasterly tip before going over the Atlantic to Ireland, England or Europe.
Depending on winds, flights are over water for 3 to 4 hours eastbound and for 4 to 5 hours westbound. Let's assume the longest time; divide 2 million (the expected number of trouble-free hours of engine operation) by 5. The result is 400,000. This means a plane should be able to cross the Atlantic 400,000 times or more without an engine problem.
That sounds reassuring, but what if one engine does fail? How likely is it that the remaining engine can be relied on to safely reach a diversionary airport? As you cross the Atlantic, an airport in Canada, Greenland, Iceland, or Ireland is—on average—an hour away. Based on demonstrated reliability, your plane should be able to divert safely 2 million times on the remaining engine.
How plausible is it that both events take place: that one engine fails while crossing and the other engine fails while diverting? For that number we multiply 2 million by 2 million. We find the overall chance of ending up in the water is one in 4 trillion. That number, I suppose, explains why we have not gotten a plane wet while flying two-engine planes across the Atlantic.
If the thought of a one in 4 trillion chance of landing in the water causes anxiety, there's a good reason for that. It has to do with how the brain is wired up. Imagine you are driving your car and another car comes at you. What action can you take? You can blow the horn, turn the wheel, or hit the brakes. As you imagine carrying out your plan, the decision-making part of the brain signals the amygdala to stop releasing stress hormones. The idea of taking action satisfies the amygdala; it drops the matter.
Imagine something going wrong in an airliner. What action can you take? None. Unable to imagine any action you can take, the amygdala is not signaled to stop the stress hormones. As stress hormones continues, so does anxiety.
The safer way to travel feels less safe. The less safe way to travel feels fine. Do you choose being safe or feeling safe? You don't have to choose. There are two ways to deal with stress hormones when flying.
- One, inhibit the release of stress hormones by producing oxytocin while in flight. Prior to flight, events that will take place during flight are associated with an oxytocin-producing memory. During flight, association triggers the release of oxytocin.
- Two, override the effect of stress hormones by what Stephen Porges calls the vagal brake. Prior to flight, events that will take place during flight are associated with a memory that stimulates the vagus nerve. During flight, association stimulates the vagus nerve, causing it to override the effect of stress hormones by slowing the heart rate and activating the parasympathetic nervous system.
Both of these methods, in addition to tools based on Cognitive Behavioral Therapy and information about how airline flying works, are detailed in courses available at http://www.fearofflying.com and in my book, SOAR: The Breakthrough Treatment for Fear of Flying. For a brief outline of how these methods can be applied, see this link at Psychology Today.
