Pilots have a unique vocabulary that includes many terms and phrases not commonly used in everyday language. One such term is “angels,” which pilots routinely use when communicating altitude. But why do pilots say angels instead of using feet or meters when referencing altitude? There are a few key reasons behind this aviation lingo.
It’s a Shorthand Reference for Altitude in Thousands of Feet
When a pilot reports being at “angels thirty eight,” or gives an altitude clearance to “descend to angels twenty,” they are using a shorthand way of communicating altitudes in thousands of feet. Specifically, angels refer to the altitude in thousands of feet above mean sea level (MSL). So angels thirty eight means an altitude of 38,000 feet above MSL. Angels twenty is 20,000 feet above MSL.
This shorthand started because calling out large altitude numbers over the radio can be tedious and lead to confusion. Saying “three eight thousand” could potentially be misheard as “eight thousand” or other numbers. Saying “angels thirty eight” is more clear and concise. It reduces radio clutter and miscommunication, while allowing pilots to get altitude information across quickly and accurately.
It Dates Back to the Early Days of Instrument Flying
Using angels to reference altitude started in the early days when aircraft began flying at high altitudes using flight instruments. In the 1920s and 30s when early airliners started flying higher than 10,000 feet, their altitudes were described in terms of “angels” over the radio to avoid the static and poor transmission quality at higher altitudes.
The term may have derived from a 1920s instrument called the ” Kollsman Angel” that referenced altitude. Some sources suggest the word angel itself implies a sense of watching over pilots as they climbed to new heights using instruments alone in the early days of flight. Regardless of its exact origin, saying angels for altitude stuck and is still standard pilot terminology today.
It’s an International Standard Aviation Term
Using angels to communicate altitude is not just a convention in the US or certain countries. It’s an internationally recognized aviation term used around the world in radio communications between pilots, air traffic control (ATC), and airline dispatch. The International Civil Aviation Organization (ICAO) includes it in its standardized aviation phraseology that pilots and ATC use to talk to each other clearly and efficiently.
So whether you’re flying between London and Paris or São Paulo and Buenos Aires, angels will be understood as altitude in thousands of feet above sea level. This standardized terminology enables clear communication between pilots and controllers speaking many different languages and accents.
Some Other Benefits of Using Angels
Beyond the main reasons of brevity, clarity, and standardization, using angels for altitude has some other advantages for aviators:
- It eliminates the risk of language confusion between feet and meters. Different countries use different primary units for altitude.
- It is more precise than saying just “thousand feet,” which could be interpreted as anywhere from 1,000 to 9,000 feet.
- It distinguishes from aviation’s use of “flight levels” defined in hundreds of feet increments.
- It works uniformly for any altitude, whereas terminology like “ten thousand” would not scale up well for higher flight levels.
For these reasons, angels has endured as the preferred global aviation term for communicating altitude quickly and unambiguously between aircraft and ground control.
Some Key Examples of Using Angels
To help understand angels in practice, here are a few examples of how it’s used by pilots and air traffic control:
- Pilot: “Center, N1234 requesting flight level three seven zero, angels thirty seven.”
ATC: “N1234, descend and maintain angels thirty seven.” - ATC: “AAL123, climb and maintain angels forty one.”
Pilot: “Up to angels forty one, AAL123.” - Pilot: “Approach, N5678 is leaving angels thirty five for two six thousand.”
ATC: “N5678, roger, descend at your discretion to two six thousand.”
In each case, angels clearly and unambiguously communicates the altitude clearance or information between the pilot and controller.
It’s Not Just for Aviation – Angels are Used in Spaceflight Too
The angels terminology is so ingrained in aviation that NASA adopted it for use during the Mercury, Gemini, Apollo, and Space Shuttle programs. During launches and orbit, Spacecraft communicate with mission control using angels to describe their altitudes in thousands of feet:
“Houston, Discovery, passing through angels two zero zero, right down the centerline.”
So next time you hear astronauts or CAPCOM use angels, you’ll recognize they are talking altitude just like aviators.
Conclusion
The decades-old aviation term “angels” used in place of altitude continues to serve an essential communication role for pilots and air traffic control. It originated as a way to improve radio clarity in early flight, but has persisted around the world thanks to the key benefits of brevity, clarity, and standardization it provides. So while it may sound odd to non-aviators, saying angels for altitude is an ingrained and practical convention of the skies.