Buzz
Nate J., a curious reader who frequently asks questions, wondered why phrases like '10-4' and 'Roger' are commonly used on walkie-talkies and two-way radios.
The Ten-Codes
The ten-codes, also known as ten-signals, are shorthand expressions used to replace common phrases in radio communication. These codes were created in 1937 by Charles Hopper, a communications director with the Illinois State Police, to address issues with radio transmissions where the first part of a message could get cut off or misunderstood. By placing 'ten' in front of each code, it gave slow radio equipment a moment to warm up, enhancing the clarity and comprehension of the key message. These codes also helped make radio messages shorter and more standardized.
The Association of Public-Safety Communications Officials-International (APCO) expanded the codes in 1974, with both law enforcement and civilian CB radio users adopting them. However, as time passed, different agencies and regions assigned varying meanings to the codes, which diminished their effectiveness as a clear and consistent system. This issue came to a head in 2005 during the aftermath of Hurricane Katrina. Following several communication failures between agencies, the United States Federal Emergency Management Agency (FEMA) advised against using ten-codes, recommending instead the use of plain, everyday language. Here’s the official APCO list.
Roger That
Back in the telegraph days, the Morse code letter R (dot-dash-dot) signified "received" or "message understood." As radio communication replaced telegraphs, the word Roger, which represented the letter R in the Joint Army/Navy Phonetic Alphabet (used by the U.S. military from 1941 to 1956), was adopted to convey the same meaning.
Despite what movies may lead you to believe, Roger simply means "last transmission received/understood" and does not imply "I will comply." For compliance, Wilco (short for Will Comply) is used. Thus, the common phrase Roger Wilco you often hear in films is redundant, since Wilco alone already confirms receipt of the message and the intent to comply.
Mayday
Mayday is a global distress signal used to indicate life-threatening emergencies. The term was introduced in 1923 by Frederick Stanley Mockford, a senior radio officer at London's Croydon Airport. Mockford was tasked with creating an easily recognizable emergency code, and since most flights at Croydon were traveling to or from Le Bourget Airport in Paris, he chose mayday, as it resembled the French phrase m'aider ("come help me").
As a distress call, the mayday signal comes with strict rules on when and how it can be used. It may only be issued when life or property is in immediate danger. Just like making false 9-1-1 calls, issuing a fake mayday is a serious crime. In the U.S., making a false distress call is a federal offense, punishable by large fines and potential imprisonment. Once a mayday call is made, no other messages can be sent except those aimed at assisting the emergency.
The correct way to issue a Mayday call is:
- "Mayday, Mayday, Mayday." The signal is repeated three times to avoid confusion with similar phrases and to differentiate it from a message about a mayday call.
- "This is ____." The name of the vessel is given three times, followed by the call sign if available.
- "Mayday. [vessel name]."
- "My position is ____." This includes the location in latitude and longitude coordinates, or alternatively, the bearing and distance from a fixed point.
- "I am _____." This indicates the type of emergency, such as a fire or sinking.
- "I require immediate assistance."
- "I have _____." This specifies the number of people on board, their condition, and any other relevant details, such as abandoning to life rafts.
- "Over."
Some radio instructors recommend the mnemonic MIPDANIO to help remember the mayday signal format: Mayday, Identify, Position, Distress, Assistance, Number of crew, Information, Over.
Phonetic or Spelling Alphabets
The issue: many letters sound very similar. When two people are communicating over the phone or a two-way radio, one might confuse an "N" for an "M," or a "B" for a "D," "T," or "C." For example, if one person tells the other that the emergency code to prevent global disaster is "M-A-T-T," a bit of static could result in the code being misheard as "N-8-B-D," putting us all at risk.
The solution: a phonetic alphabet or spelling alphabet, where each letter is assigned a distinct code word that starts with the same letter (e.g., Alpha for "A"). Using the Joint Army/Navy Phonetic Alphabet, the code "M-A-T-T" becomes "Mike-Able-Tare-Tare," which is much harder to misinterpret.
The most widely used spelling alphabet today is the International Radiotelephony Spelling Alphabet. This alphabet was created by the International Air Transport Association (IATA) and the International Civil Aviation Organization (ICAO) after World War II. It was later adopted by numerous organizations, including the 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 helped it spread globally and become commonly known as the NATO phonetic alphabet.
In addition to these organizations, the alphabet is also utilized by the military and various civilian sectors such as retail, IT, and airlines. The current version of the alphabet is as follows: 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.
