science

Minimum off-route altitude

Minimum off-route altitude is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Minimum off-route altitude rather than just read about it. In short: A minimum off-route altitude (MORA) provides a quick way for an aircraft pilot to read the minimum altitude required for terrain and obstacle clearance. MORAs give at least 1,000 feet altitude clearance above terrain and obstacles such as radio masts, and 2,000 feet where the terrain and obstacles exceed 5,000 feet.

Key takeaways

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

Reference excerpt

A minimum off-route altitude (MORA) provides a quick way for an aircraft pilot to read the minimum altitude required for terrain and obstacle clearance. MORAs give at least 1,000 feet altitude clearance above terrain and obstacles such as radio masts, and 2,000 feet where the terrain and obstacles exceed 5,000 feet. MORAs are given feet, rounded up to the nearest 100 and omitting the last two figures. For example, 7,550 feet would be given as 76. There are two types of MORAs: the route MORA and the grid MORA. Route MORAs provide an obstacle clearance within 10 nautical miles (19 km) on both sides of the airways and within a 10-nautical-mile (19 km) radius around the ends of the airways. Grid MORAs provide an obstacle clearance altitude within a latitude and longitude grid block, usually of one degree by one degree. MORAs were created by Jeppesen and used on their airways charts. Some countries specify Minimum Enroute Altitudes (MEAs), minimum obstruction clearance altitudes (MOCAs), and Off Route Obstacle Clearance Altitudes (OROCAs), which have slightly different rules. An MEA gives a minimum altitude for reception of navigation aids and radio communications, and is found only within controlled airspace. An OROCA gives 2000 feet of clearance only in mountainous areas.

References

Worked examples

Example 1 — a first encounter with Minimum off-route altitude

Start with the simplest possible case. Write down what Minimum off-route altitude 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 Minimum off-route altitude 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 Minimum off-route altitude 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 Minimum off-route altitude

In research: Minimum off-route altitude 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 Minimum off-route altitude 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: Minimum off-route altitude is common in secondary-school and first-year university syllabi. It links to neighbouring topics Air navigation, Air traffic control, Aviation stubs, so understanding it makes those chapters shorter.
In everyday life: Look for Minimum off-route altitude 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.

Ask Teacher Smith questions about this articleOpens your AI tutor with a question about “Minimum off-route altitude” →

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study Minimum off-route altitude in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Minimum off-route altitude 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 Minimum off-route altitude out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Minimum off-route altitude in simple terms?

Why does Minimum off-route altitude 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 Minimum off-route altitude?

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 Minimum off-route altitude.