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What's Up With "10-4" And Other Radio Lingo?

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Reader and frequent question-asker Nate J. wrote in wondering why we say things like "10-4" and "Roger" on walkie-talkies and other two-way radios.

The Ten-Codes

The ten-codes or ten-signals are code words used as stand-ins for common phrases in radio communication. Charles Hopper, a communications director with the Illinois State Police, developed them in 1937 to combat the problem of the first syllables or words of a transmission being cut off or misunderstood. Preceding every code with "ten" gave the sometimes slow equipment time to warm up and improved the likelihood that a listener would understand the important part of a message. The codes also allowed for brevity and standardization in radio message traffic.

The codes were expanded by the Association of Public-Safety Communications Officials-International (APCO) in 1974 and were used by both law enforcement agencies and civilian CB radio users. Over time, differing meanings for the codes came about in different agencies and jurisdictions, undoing the codes' usefulness as a concise and standardized system. The problem came to a head in 2005 during rescue operations after Hurricane Katrina. After several instances of inter-agency communication problems, the United States Federal Emergency Management Agency (FEMA) discouraged the use of ten-codes and today the federal government recommends they be replaced with plain, everyday language. Here's the official APCO list.

Roger That

In the days of the telegraph, the Morse code letter R (dot-dash-dot) was sometimes used to indicate "received" or "message received/understood." When radio voice communication began to replace telegraphs, Roger, the code word assigned to the letter R in the Joint Army/Navy Phonetic Alphabet (the radio alphabet used by all branches of the United States military from 1941 to 1956), took on the same role.

Contrary to what Hollywood would have you think, Roger only means "last transmission received/understood" and does not also mean or imply "I will comply." Wilco (Will Comply) is the code used if the speaker intends to convey "message received and will comply." Given that, the phrase Roger Wilco, which you so often hear in the movies, is redundant and not really used since Wilco alone covers all the bases and acknowledges receipt of message and states intent to comply.

Mayday


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Mayday is an international code word used to signal life-threatening emergencies. It was originated in 1923 by Frederick Stanley Mockford, a senior radio officer at London's Croydon Airport. He was given the task of coming up with a unique and easily understandable emergency code word. Most of the air traffic at Croydon was either coming from or going to Le Bourget Airport in Paris, so Mockford chose mayday because of its similarity to the French m'aider ("come help me").

Because it is an emergency signal, there are plenty of rules governing the use and format of a mayday call. A mayday call can only be made when life or craft is in imminent danger of death or destruction (and, as with fake 9-1-1 calls, fake mayday calls are considered serious crimes. In the U.S., making a fake distress call is a federal crime that can carry large fines and jail time), and once one is made, no other messages can be transmitted except to assist in the emergency.

Correct format for a Mayday call is:

- "Mayday, Mayday, Mayday." The call is always given three times in a row to keep it from being mistaken for a similar-sounding phrase, or to distinguish an actual distress signal from a message about a mayday call.

- "This is ____." The vessel name is repeated three times, followed by call sign if available.

- "Mayday. [vessel name]."

- "My position is ____." Position is given in latitude-longitude coordinates, or bearing and distance from a fixed point.

- "I am _____." The type of emergency, e.g. fire or sinking.

- "I require immediate assistance."

- "I have _____." The number of people on board and their condition, as well as any other pertinent information, e.g. abandoning to life rafts.

- "Over."

Some radio instructors suggest the mnemonic MIPDANIO for learning mayday signal format: Mayday, Identify, Position, Distress, Assistance, Number of crew, Information, Over.

Phonetic or Spelling Alphabets

The problem: a lot of letters sound alike. If two people are talking to each other on the telephone or a two-way radio, an "N" might be misheard as an "M," or a "B" might be heard as a "D," "T," or "C." If one person tells the other that the secret code that must be entered to save the world from imminent disaster is "M-A-T-T", there's a chance that we might all die because a little bit of static could cause the code to be heard as "N-8-B-D."

The solution: a phonetic alphabet or spelling alphabet, where code words are assigned to the letters of the alphabet acrophonically (that is, the code word assigned to a given letter starts with that letter, like Alpha for "A"). Using the Joint Army/Navy Phonetic Alphabet mentioned earlier, the above code becomes "Mike-Able-Tare-Tare" which is a little harder to mishear.

Today, the most commonly used spelling alphabet is the International Radiotelephony Spelling Alphabet. The alphabet was developed by the International Air Transport Association (IATA) and International Civil Aviation Organization (ICAO) after World War II and later adopted by organizations like International Maritime Organization (IMO), the Federal Aviation Administration (FAA), the American Radio Relay League (ARRL), and the North Atlantic Treaty Organization (NATO) (whose use of the alphabet led to its global spread and use of the common name, NATO phonetic alphabet).

In addition to these (and other) organizations, the alphabet is used by the military and in civilian industries (retail, IT and airlines for instance). The alphabet in its current form is:
Alfa
Bravo
Charlie
Delta
Echo
Foxtrot
Golf
Hotel
India
Juliet
Kilo
Lima
Mike
November
Oscar
Papa
Quebec
Romeo
Sierra
Tango
Uniform
Victor
Whiskey
X-ray
Yankee
Zulu.

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Big Questions
Why Do Baseball Managers Wear Uniforms?
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Basketball and hockey coaches wear business suits on the sidelines. Football coaches wear team-branded shirts and jackets and often ill-fitting pleated khakis. Why are baseball managers the only guys who wear the same outfit as their players?

According to John Thorn, the official historian of Major League Baseball since 2011, it goes back to the earliest days of the game. Back then, the person known as the manager was the business manager: the guy who kept the books in order and the road trips on schedule. Meanwhile, the guy we call the manager today, the one who arranges the roster and decides when to pull a pitcher, was known as the captain. In addition to managing the team on the field, he was usually also on the team as a player. For many years, the “manager” wore a player’s uniform simply because he was a player. There were also a few captains who didn’t play for the team and stuck to making decisions in the dugout, and they usually wore suits.

With the passing of time, it became less common for the captain to play, and on most teams they took on strictly managerial roles. Instead of suits proliferating throughout America’s dugouts, though, non-playing captains largely hung on to the tradition of wearing a player's uniform. By the early to mid 20th century, wearing the uniform was the norm for managers, with a few notable exceptions. The Philadelphia Athletics’s Connie Mack and the Brooklyn Dodgers’s Burt Shotton continued to wear suits and ties to games long after it fell out of favor (though Shotton sometimes liked to layer a team jacket on top of his street clothes). Once those two retired, it’s been uniforms as far as the eye can see.

The adherence to the uniform among managers in the second half of the 20th century leads some people to think that MLB mandates it, but a look through the official major league rules [PDF] doesn’t turn up much on a manager’s dress. Rule 1.11(a) (1) says that “All players on a team shall wear uniforms identical in color, trim and style, and all players’ uniforms shall include minimal six-inch numbers on their backs" and rule 2.00 states that a coach is a "team member in uniform appointed by the manager to perform such duties as the manager may designate, such as but not limited to acting as base coach."

While Rule 2.00 gives a rundown of the manager’s role and some rules that apply to them, it doesn’t specify that they’re uniformed. Further down, Rule 3.15 says that "No person shall be allowed on the playing field during a game except players and coaches in uniform, managers, news photographers authorized by the home team, umpires, officers of the law in uniform and watchmen or other employees of the home club." Again, nothing about the managers being uniformed.

All that said, Rule 2.00 defines the bench or dugout as “the seating facilities reserved for players, substitutes and other team members in uniform when they are not actively engaged on the playing field," and makes no exceptions for managers or anyone else. While the managers’ duds are never addressed anywhere else, this definition does seem to necessitate, in a roundabout way, that managers wear a uniform—at least if they want to have access to the dugout. And, really, where else would they sit?

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

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Big Questions
How Long Could a Person Survive With an Unlimited Supply of Water, But No Food at All?
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How long could a person survive if he had unlimited supply of water, but no food at all?

Richard Lee Fulgham:

I happen to know the answer because I have studied starvation, its course, and its utility in committing a painless suicide. (No, I’m not suicidal.)

A healthy human being can live approximately 45 to 65 days without food of any kind, so long as he or she keeps hydrated.

You could survive without any severe symptoms [for] about 30 to 35 days, but after that you would probably experience skin rashes, diarrhea, and of course substantial weight loss.

The body—as you must know—begins eating itself, beginning with adipose tissue (i.e. fat) and next the muscle tissue.

Google Mahatma Gandhi, who starved himself almost to death during 14 voluntary hunger strikes to bring attention to India’s independence movement.

Strangely, there is much evidence that starvation is a painless way to die. In fact, you experience a wonderful euphoria when the body realizes it is about to die. Whether this is a divine gift or merely secretions of the brain is not known.

Of course, the picture is not so pretty for all reports. Some victims of starvation have experienced extreme irritability, unbearably itchy skin rashes, unceasing diarrhea, painful swallowing, and edema.

In most cases, death comes when the organs begin to shut down after six to nine weeks. Usually the heart simply stops.

(Here is a detailed medical report of the longest known fast: 382 days.)

This post originally appeared on Quora. Click here to view.

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