The Secrets of Airline Travel Quiz

Airplane windows used to be square, but as planes started getting bigger, those sharp edges created natural weak spots, causing "metal fatigue failure" and broken windows. Now, manufacturers put in rounded windows because they're better able to handle the cabin pressure changes, as well as other stressors.

A tailwind helps a lot because it literally pushes the plane faster. A headwind does just the opposite and slows everything down. Route adjustments can also help a pilot catch up. Increasing airplane speed only burns more fuel and doesn't save much time.

Increased air travel after World War I meant an internationally recognizable signal for aircraft emergencies was necessary. A British radio officer came up with "m'aider," French for "help me" because a lot of the air traffic was between England and France. The U.S. modified the spelling, although not the pronunciation, into "mayday."

The very first flight attendants were all registered nurses, although that job requirement was axed when World War II caused many nurses to enlist. In 1936, "air hostesses" also had to be very small, under 5 feet 4 inches (1.6 meters) and weigh 100 to 118 pounds (45 to 53 kilograms).

Cleaning crews are extremely efficient, and can clean and disinfect an entire plane in 15 minutes. Delta does a "deep clean" on planes that sit for more than eight hours, which involves removing seat cushions and even shampooing the carpet.

The U.S. National Weather Service says a commercial plane gets hit by a bolt of lightning on average once or twice per year. Fortunately, airplanes are designed to handle lightning strikes, so the pilots and passengers are in no danger.

The warmest part of the airplane is in the very back, so sit there if you're the type of person who is always freezing.

The tray tables are hands-down the germiest parts of any airplane. They're generally only cleaned once a day, not between flights. It's a good idea to wipe down the tray table with a sanitizing wipe. Do the TV screen, seat belt buckle and armrests while you're at it.

Flight attendants have used their scarves in all kinds of situations. Visible tattoos are not allowed by most airlines so the scarf covers up a neck tattoo. Also flight attendants have been known to use scarves as makeshift splints and bandages onboard a flight.