science

Obstacle departure procedure

Obstacle departure procedure 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 Obstacle departure procedure rather than just read about it. In short: Obstacle departure procedure (ODP) is a type of departure procedure that provides obstruction clearance via the least onerous route from an airport to an appropriate en-route structure. Pilots can fly ODPs without prior clearance unless assigned a standard instrument departure or radar vectored by air traffic controllers.

Key takeaways

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

Reference excerpt

Obstacle departure procedure (ODP) is a type of departure procedure that provides obstruction clearance via the least onerous route from an airport to an appropriate en-route structure. Pilots can fly ODPs without prior clearance unless assigned a standard instrument departure or radar vectored by air traffic controllers.

Print ODPs may be designed using either conventional or area navigation (RNAV) criteria. ODPS can be either graphical or textual; graphical ODPs always note "(OBSTACLE)" in the title.

Development

When an airport is being analyzed for designing an instrument approach procedure, an obstacle departure procedure assessment is conducted first. Pass the departure end of the runway, Surveyors establish an obstacle clearance surface (OCS), which is an imaginary surface that rises at a 40:1 ratio under standard conditions, or 152ft per nautical miles. The OCS can rise more steeply if terrain or other obstacles are present. Pass the departure end of the runway at 35ft above ground, if an aircraft can maintain 48ft per nautical mile clearance above the OCS, a clearance requirement known as required obstacle clearance (ROC), or maintain a climb rate of 200ft per nautical mile for standard 40:1 ratio OCS, no ODP will be established. Otherwise, an ODP is included with the instrument procedure. Obstacles located within 1 nautical mile of the departure end of runway but penetrate the OCS are considered "low, close-in obstacles". To avoid publishing a steep climb gradient, these obstacles' locations and heights are noted in Terminal Procedures Publication. Commonly, ODPs are developed under the assumption that the aircraft will:

Cross the departure end at least 35 feet above runway departure end elevation; Climb to 400 feet above runway departure end elevation before turning; Maintain climb gradient > 200 ft per nautical mile until reaching minimum IFR altitude. Unlike Standard Instrument Departures, ODPs are generally developed for smaller airports. It is also assumed that all aircraft engines are in normal operation during the climb, as opposed to being a safeguard for twin engine planes with one engine inoperative.

Notes

References

Illustrations

Worked examples

Example 1 — a first encounter with Obstacle departure procedure

Start with the simplest possible case. Write down what Obstacle departure procedure 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 Obstacle departure procedure 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 Obstacle departure procedure 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 Obstacle departure procedure

In research: Obstacle departure procedure 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 Obstacle departure procedure 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: Obstacle departure procedure is common in secondary-school and first-year university syllabi. It links to neighbouring topics Aviation publications, Flight planning, so understanding it makes those chapters shorter.
In everyday life: Look for Obstacle departure procedure 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 “Obstacle departure procedure” →

Affiliate

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

How to study Obstacle departure procedure in 20 minutes

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

Frequently asked questions

What is Obstacle departure procedure in simple terms?

Why does Obstacle departure procedure 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 Obstacle departure procedure?

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 Obstacle departure procedure.