Many travellers have likely heard announcements such as Code Bravo while wandering around the airport .
But what does Code Bravo and others like it mean?
Experts have lifted the curtain on the codes that travellers or commuters aren't supposed to know - and some of them are harrowing or humorous.
Birmingham Post and Mail
A general security alert will be raised via Code Bravo, the Telegraph reported.
Code Adam may be used to alert staff of a missing child.
Mayday, meanwhile, means an aircraft or ship is facing imminent danger.
The code 7500 is a transponder code which means an aircraft has been, or is threatened with, hijacking.
While 7700 is a more general emergency code, 7600 indicates a radio failure.
Cabin crew, meanwhile, will use "arm and crosscheck" - meaning, prior to departure, the plane exits are put into emergency mode.
"Hat bin" is a term for overhead bins, while "hot bit" refers to the heated part of an in-flight meal.
A rubbish bag is actually a "gash bag" and plonkey kits are a bag of essentials carried by flight attendants.
A pilot will refer to his "flight level" - which is how many thousands of feet above sea level you are - and his "deadhead", a pilot or flight attendant who is one repositioning as part of an on-duty assignment.
Cruise ship codes
The announcement Operation Bright Star signals a medical emergency.
Operation Rising Star, meanwhile, means a passenger has passed away.
Code Red - rather than being a death - is an outbreak of norovirus or illness.
Similarly, Code Green and Code Yellow indicate less severe illness-related problems.
Oscar, Oscar, Oscar - rather than them demanding an Academy Award - means a man has gone overboard.
Similarly, Charlie, Charlie, Charlie is a security threat, and Echo, Echo, Echo a possible collision with another ship, or in other cases a warning of high winds.
Red Parties means a possible fire on board, Bravo, Bravo, Bravo another serious incident, Delta is damage to the ship and Priority 2 is a leak.
The best known code is Inspector Sands, or simply Mr Sands, which refers to a potential emergency such as a fire or bomb scare.
The numbered codes - Code 1, 2, 3 etc - refer to cleaning jobs, rather than anything sinister.
Code 1 means blood, whereas 2, 3 and 4 mean urine, vomit and spillage respectively.
Code 5 is used to signify broken glass, while 6 and 7 is little and anything else that doesn't fit into the categories.