science

Maximum elevation figure

Maximum elevation figure 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 Maximum elevation figure rather than just read about it. In short: Maximum elevation figure (MEF) is a type of visual flight rule (VFR) information that indicates the elevation of the highest geographical feature within a GEOREF quadrangle area. It is of interest to pilots, who want to be aware of the highest mountain peaks and tall towers nearby, so that they can fly above them to avoid controlled flight into terrain.

Key takeaways

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

Reference excerpt

Maximum elevation figure (MEF) is a type of visual flight rule (VFR) information that indicates the elevation of the highest geographical feature within a GEOREF quadrangle area. It is of interest to pilots, who want to be aware of the highest mountain peaks and tall towers nearby, so that they can fly above them to avoid controlled flight into terrain. ("Features" includes terrain, trees, towers, and other obstacles.) Much like the minimum safe altitude (MSA) used for flight under instrument flight rules, the MEF includes a margin for aircraft clearance above the terrain and altimeter error. In a VFR flight, the MEF is commonly referred to as a "quadrantal altitude" (not to be confused with an IFR minimum sector altitude).

United States In the US, the Federal Aviation Administration issues sectional charts. Each rectangular area covering one degree of latitude and one degree of longitude is divided into four smaller areas called quadrangles (in accordance with the World Geographic Reference System, or GEOREF), each spanning half a degree of latitude and half a degree of longitude. Each quadrangle has its MEF printed in it in thousands and hundreds of feet above mean sea level. For example, 105, means that the highest elevation is 10,500 feet within that quadrangle. MEFs are determined by taking the highest of the following: 1) The point of highest terrain within a quadrangle, adding 200 ft for obstacles which are not required to be portrayed, and then adding 100 feet for vertical error and then rounding up to the next hundred feet; or 2) The height of the highest manmade obstacle in the quadrangle, adding 100 feet for vertical error and then rounding up to the next hundred feet.

Canadian VNCs The MEF on Canadian VFR navigation charts is calculated by taking the higher value of:

the top elevation of the highest obstacle plus the vertical accuracy (a variable number of feet) of the terrain source data; or the elevation of the highest terrain plus 328 feet plus the vertical accuracy variable of the terrain source data.

Australia In Australia, Visual Navigation Charts (VNCs) and Visual Terminal Charts (VTCs) usually indicate MEF information by use of bold elevation figures for each grid. Pilots are also required to ensure their planned route does not contravene the minimum flying altitude regulations contained in CAR 167. This restriction is normally 1000FT above populated or built-up areas and 500FT elsewhere. Procedures are different when flights are conducted under IFR, where LSALT is commonly used. LSALT may be determined in a number of ways as explained in the Australian Aeronautical Information Publication or AIP.

See also Minimum safe altitude (for IFR flight), including area minimum altitudes (AMA)

References

Illustrations

Worked examples

Example 1 — a first encounter with Maximum elevation figure

Start with the simplest possible case. Write down what Maximum elevation figure 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 Maximum elevation figure 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 Maximum elevation figure 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 Maximum elevation figure

In research: Maximum elevation figure 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 Maximum elevation figure 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: Maximum elevation figure is common in secondary-school and first-year university syllabi. It links to neighbouring topics Altitudes in aviation, Aviation stubs, Cartography, so understanding it makes those chapters shorter.
In everyday life: Look for Maximum elevation figure 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.

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How to study Maximum elevation figure in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Maximum elevation figure 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 Maximum elevation figure out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Maximum elevation figure in simple terms?

Why does Maximum elevation figure 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 Maximum elevation figure?

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 Maximum elevation figure.