This article uses about 80% of the ASD-STE100 rules. The sentences are short. The verbs are active. Each word has one meaning. That is the point.
On October 1, AI researcher Andrej Karpathy shared tips to help people understand the output of language models. His first tip: tell the model to write in ASD-STE100. Karpathy’s post.
ASD-STE100 is not a new AI tool. It is a rule set for English that the aerospace industry made for aircraft maintenance manuals. Karpathy writes that models know the rules well, and that the result is often “a lot more readable.” He also suggests a softer version: “80% of the way to ASD-STE100.”
For a student, this is a useful study method. It also shows how an aviation standard can be useful outside aviation.
Why aviation made its own English
Mechanics around the world use the same maintenance manuals. Many of these mechanics do not speak English as their first language. A long sentence or a word with two meanings can cause a person to do a step incorrectly. On an aircraft, an incorrect step can cause an accident.
In the early 1980s, European airlines asked for a solution. AECMA, the European association of aerospace manufacturers, examined controlled languages and released the Simplified English Guide in the mid-1980s. After AECMA merged into ASD in 2004, the guide became ASD-STE100 Simplified Technical English. Issue 9, released in January 2025, is the current version. The specification is free; you can request a copy from the ASD-STE100 website. Wikipedia summary.
The main rules
The full standard has 53 writing rules and a dictionary of about 900 approved words. These are the rules that have the largest effect:
- Short sentences. Procedures: 20 words maximum. Descriptions: 25 words maximum.
- One word, one meaning. The dictionary gives each approved word one meaning and one part of speech. For example, “close” means to shut. It does not mean “near.”
- Active voice. Write “Remove the panel,” not “The panel should be removed.”
- One instruction per sentence in procedures. Put warnings before the step they apply to.
- No unnecessary words. Do not use filler phrases, nested clauses, or vague qualifiers.
Today, many industries outside aerospace also use STE. Examples include automotive, energy, and medical devices. TechScribe overview.
Why it works on AI output
Language models often write long sentences, add qualifiers, and repeat the same idea. STE does not permit most of these patterns. When you ask for STE, the model must:
- Put one idea in each sentence.
- Use the same word for the same thing every time.
- Show who does each action.
The result is an answer that you can read quickly and check step by step. If a step is wrong, it is easy to find.
Try it: the prompt
Copy this prompt into the AI tool that you use. Change the topic.
Explain how a jet engine makes thrust. Write about 80% of the way to ASD-STE100 Simplified Technical English: short sentences, active voice, one meaning per word, no filler. If a technical term is necessary, define it the first time you use it.
Then compare the result with the answer to the same question without the STE instruction. Count the words. Find the sentences that you had to read two times.
Some tips:
- Use the 80% version for learning. Full STE can feel too strict for explanations. The 80% version keeps the clarity and permits a few useful words.
- Use full STE for procedures. For a checklist or a set of steps, ask for strict STE with numbered steps.
- Use it to edit your own writing. Paste your lab report or project summary and ask the model to rewrite it in STE. Then compare the two versions. This shows you where your sentences are too long.
- Always check the facts. Clear writing is not the same as correct writing. A model can state an incorrect fact in very clear English.
The career connection
STE is a real skill in aerospace jobs. Technical writers use it to write maintenance manuals, often with the S1000D documentation standard. Aircraft mechanics read STE every day. Engineers who write service bulletins and work instructions use the same rules.
If you plan a career in aviation maintenance or avionics, you will read STE text at work. If you can write in it, you have a skill that many applicants do not have. Our article on the aircraft mechanic shortage and the A&P license explains how to start on that path.
For more ways that AI tools connect to aerospace work, see the AI in Aerospace synthesis topic. For a hands-on project, try Your First Aerospace AI Project.