Mayday

Key takeaways

Mayday belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Mayday to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Mayday from memory before moving on to harder problems.

Reference excerpt

Mayday is an emergency procedure word used internationally as a distress signal in voice-procedure radio communications. It is used to signal a life-threatening emergency primarily by aviators and mariners, but in some countries local organizations such as firefighters, police forces, and transportation organizations also use the term. Convention requires the word be repeated three times in a row during the initial emergency declaration ("Mayday, mayday, mayday").

History The "mayday" procedure word was conceived as a distress call in the early 1920s by Frederick Stanley Mockford, officer-in-charge of radio at Croydon Airport, England. He had been asked to think of a word that would indicate distress and would easily be understood by all pilots and ground staff in an emergency. Since much of the air traffic at the time was between Croydon and Le Bourget Airport in Paris, he proposed the term "mayday", the phonetic equivalent of the French m'aider. The phrase itself does sacrifice grammatical accuracy (meaning literally "to help me") in favour of communicability and recognition. Looking through the lens of French grammar, it may be a short form of venez m'aider, "come help me". Venez m'aider is the closest phonetic phrase to "mayday", but the technically accurate standalone reflexive imperative conjugation would be aidez-moi. Following tests, the new procedure word was introduced for cross-Channel flights in February 1923. The previous distress call had been the Morse code signal SOS, but this was not considered suitable for voice communication, "[o]wing to the difficulty of distinguishing the letter 'S' by telephone". In 1927, the International Radiotelegraph Convention of Washington, D.C. adopted the voice call "mayday" as the radiotelephone distress call in addition to the SOS radiotelegraph (Morse code) signal.

Mayday calls

If a mayday call cannot be sent because a radio is not available, a variety of other distress signals and calls for help can be used. Additionally, a mayday call can be sent on behalf of one vessel by another; this is known as a mayday relay. Civilian aircraft making a mayday call in the United States airspace are encouraged by the Federal Aviation Administration to use the following format, omitting any portions as necessary for expediency or where they are irrelevant (capitalization as in the original source):

Mayday, Mayday, Mayday; (Name of station addressed); Aircraft call sign and type; Nature of emergency; Weather; Pilot's intentions and/or requests; Present position and heading, or if lost then last known position and heading and time when the aircraft was at that position; Altitude or Flight level; Fuel remaining in minutes; Number of people on board; Any other useful information. Making a false distress call is a criminal offence in many countries, punishable by a fine, restitution, and possible imprisonment.

Other urgent calls

Pan-pan

"Pan-pan" (from French: panne, "a breakdown") indicates an urgent situation of a lower order than a "grave and imminent threat requiring immediate assistance", such as a mechanical failure or a medical problem. The suffix "medico" originally was to be added by vessels in British waters to indicate a medical problem ("pan-pan medico", repeated three times), or by aircraft declaring a non-life-threatening medical emergency of a passenger in flight, or those operating as protected medical transport in accordance with the Geneva Conventions. "Pan-pan medico" is no longer in official use.

Declaring emergency Sometimes the phrase "declaring emergency" is used in aviation, as an alternative to calling "mayday". For example, in 1998 Swissair Flight 111 radioed "Swissair one-eleven heavy is declaring emergency" after their situation had worsened, upgrading from the "pan-pan" which was declared earlier. However, the International Civil Aviation Organization recommends the use of the standard "pan-pan" and "mayday" calls instead of "declaring an emergency". Cases of pilots using phrases other than "pan-pan" and "mayday" have caused confusion and errors in aircraft handling.

Silencing other communications traffic

"Seelonce mayday" (using an approximation of the French pronunciation of silence) is a demand that the channel only be used by the vessel/s and authorities involved with the distress. The channel may not be used for normal working traffic until "seelonce feenee" is broadcast. "Seelonce mayday" and "seelonce feenee" may only be sent by the controlling station in charge of the distress. The expression "stop transmitting – mayday" is an aeronautical equivalent of "seelonce mayday". "Seelonce distress" and "prudonce" are no longer in use since ITU WRC-07. The format for a "seelonce mayday" is MAYDAY, All Stations x3 or [Interfering station] x3, this is [controlling station], SEELONCE MAYDAY. "Seelonce feenee" (from French silence fini, 'silence finished') means that the emergency situation has been concluded and the channel may now be used normally. "Distress traffic ended" is the aeronautical equivalent of "seelonce feenee". The format for the "seelonce feenee" is MAYDAY, All stations x3, this is [controlling station] x3, date and time in UTC, distressed vessel's MMSI number, distressed vessel's name, distressed vessel's call sign, SEELONCE FEENEE.

See also Aircraft emergency frequency CQD Global Maritime Distress Safety System Sécurité Vessel emergency codes

References

External links Handling Distress and Help Calls ACP135(F): Communications Instructions: Distress and Rescue Procedures Boating Safety: A VHF Primer, the use and misuse of the VHF Dead passenger on plane after bird strikes on YouTube Transport Canada: Radio Distress Procedures Card TP9878

Worked examples

Example 1 — a first encounter with Mayday

Start with the simplest possible case. Write down what Mayday claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Mayday before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Mayday ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Mayday

In research: Mayday appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Mayday in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Mayday is common in secondary-school and first-year university syllabi. It links to neighbouring topics Distress signals, Emergency communication, History of air traffic control, so understanding it makes those chapters shorter.
In everyday life: Look for Mayday outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

How to study Mayday in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Mayday means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Mayday out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Mayday in simple terms?

Mayday is an emergency procedure word used internationally as a distress signal in voice-procedure radio communications. It is used to signal a life-threatening emergency primarily by aviators and mariners, but in some countries local organizations such as firefighters, police forces, and transport…

Why does Mayday matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Mayday?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Mayday.