The airliner is one of the pinnacles of the modern era: beautifully engineered, high-tech, bewilderingly complex, but accessible by all. Billions of people have traveled at blistering speeds at unimaginable altitudes to every corner of the world, often without a second thought for the enormous amount of technology and engineering all around them. Air travel arguably has done more to unite the globe than any other invention known to man. We live in the jet age.
But there are some things even frequent flyers have never realized about the aircraft they travel in, small peculiarities about the modern airliner that live outside the realm of most people’s common knowledge. Until now, that is.
10 There Are Explosive Charges Inside The Engines
Let’s ignore the fact that the entire wing is filled with dangerous and highly flammable fuel for a second (yes, that’s where the fuel goes). Each engine also comes fully equipped with one (sometimes two) explosive charges, which are known as “squibs.” Surprisingly, these are used to combat engine fires. Upon firing, the explosive charge punctures the airtight seal of a highly pressurized bottle, and a fire-retardant chemical is violently expelled all over the engine’s interior to—hopefully—smother any flames that remain in the engine casing.
Most aircraft come equipped with two charges—the idea is that firing one should do the trick, but if that fails the second should buy the aircraft a few more precious seconds while it finds somewhere nearby to land. The fire suppression systems in aircraft cargo bays work under similar principles. It’s comforting, in a rather bizarre way.
9 Your Aircraft Might Be More Broken Than You Think
Every company wants its planes to fly, as often as they can, with as full a load as they can. If an aircraft isn’t in the sky, it doesn’t earn any money. So when part of the aircraft breaks, there is tremendous pressure on the part of the airline to get the flight underway again as soon as possible. But full-blown repair jobs can take hours, potentially even days, and there are times when a breakage could be seen as trivial, such as a malfunctioning coffee pot or a broken lightbulb. So what decides whether a broken component means an aircraft can’t fly?
The answer is a document known as the MEL, or Minimum Equipment List. Any failure is looked up in this list, and it will let you know whether you need it for a particular flight; it also outlines any procedures the pilots must apply to cope with its loss. What this system permits, however, are aircraft flying around in the sky that are potentially operating with only half the usual systems. It’s still safe, of course—unless that other half also decides to fail, and then the redundancy is gone. Ultimately, it’s up to the captain of the flight to decide whether or not to take the aircraft in its current state, but the company can always swap to another captain who would be willing to accept it.
In the middle of a busy summer season, when an airline cannot afford to fix something but can instead continually defer its repair (up to a point), there is little incentive to properly maintain the aircraft until the end of the season, which means that many aircraft in service today are defective in some way or other.
8 The Cabin Air Comes From The Engines, Not The Outside
Cabin air is not the same as the air outside the aircraft. At the altitudes that commercial airliners fly at, the air has the same composition (still 20 percent oxygen), but it’s far too thin for a person to breathe and also hope to remain conscious. The solution that engineers came up with was to take air from the engines, engines that already compress the air for their own use, so that there is a supply of denser, usable air for the passengers to breathe. It still won’t be the equivalent of the air on the ground, of course—that would make too much of a difference in pressure between the inside and the outside of the cabin—so most aircraft look for a happy medium. The air you’re breathing is basically what you’d find at an altitude of 2,400 meters (8,000 ft).
The downside to this system is, of course, that anything that goes through the engine is also likely to end up in the cabin, such as noxious smoke if the engine catches fire, fumes from de-icing fluid, or, as has been increasingly reported, toxic compounds from the burning of lubricating oils within the engine itself.