Aerophobia is the name for flight anxiety, and it’s fairly common. Even those who don’t have this phobia can still experience fear while flying. It’s easy — but not recommended — to start imagining all the ways the flight could end in disaster. All it takes is a little turbulence for the imagination to run wild. To avoid mass panic, the cabin crew only uses a series of codes to maintain order.
Flight attendant and author on Flyertalk.com Amanda Pleva explained some of the jargon used in emergency situations.
“Codes are used by crew in order to maintain calm and order in the cabin,” she said. “We’re specially trained in emergency situations, and panic can cause us to lose control of a situation and end up in injury or death.” 
However, there’s one phrase you don’t want to hear en route.
The Seven Word Code That Means The Engine Has Failedy
One of our engines is indicating improperly. This means one of the engines had failed — but don’t panic yet. A failed engine is not as scary as it seems, and it has a simple solution: Land at the nearest airport available. Or, sometimes, just keep flying. Planes are able to continue even if one engine fails because of the built-in safety features and back-up engines. A failed engine basically means the aircraft has lowered fuel efficiency and range. It definitely does not mean “we’re going to crash-land.” In fact, passengers may not realize when it occurs. And fortunately, it’s an extremely unlikely occurrence anyway. 
In addition to the above, there are other codes as well.
More Codes You Don’t Want to Hear on Your Next Flight
If you hear the pilot use the code “7500,” that means there has been a threat of hijacking.
Flight attendants do not have easy jobs. Their roles include serving food and drinks, keeping people safe, and maintaining order in a tight, enclosed space for hours at a time. Plus, not all passengers are calm and courteous.
“If a passenger is being very rude and difficult, then it’s not unheard of for a flight attendant to break wind and ‘cropdust’ past the offender,” Pleva explained. “Childish? Yes. Satisfying? Also yes.”
This code is named after Adam Walsh, a child who got abducted in 1981 at a department store. A “code Adam” reports a missing child.
This is another term for turbulence.