Confirm VOR system accuracy with a TO indication when selecting 183 degrees on the CDI

VOR navigation basics in everyday flight terms

If you’ve spent time wading through a chart, dialing up a VOR, and watching that CDI needle settle just right, you know there’s a certain satisfaction in harmony between plan and instruments. VORs are like the old reliable friends of IFR flying: steady, predictable, and a touch opinionated about which way you’re headed. The CDI—your Course Deviation Indicator—tells you if you’re on the course you’ve chosen or if you need to tuck back toward it. When the CDI centers on a particular course, that center-line feel isn’t magic. It’s a sign you’re tracking the intended radial with the VOR station doing its job in the background.

What the CDI is really saying

In plain terms, a VOR transmits a signal that allows your NAV radio to compare your aircraft’s position with the radial you’ve selected. The OBS knob (the thing you use to set a course) tells the NAV receiver which direction you want to fly relative to the station. If you set a course and the CDI needle sits dead center, you’re aligned with that course. But the needle’s center isn’t a one-way street—it’s coupled with the TO/FROM indicator to tell you not just where you are heading, but where you’re headed toward.

TO vs FROM: what that means in the real world

• TO means you’re flying toward the VOR station along the course you’ve set.

• FROM means you’re flying away from the VOR along the same course.

Think of it like a compass on a rental bike: you set a direction, and the indicator confirms whether you’re moving toward the beacon or away from it. The combination of a centered CDI and a TO or FROM reading is the cockpit’s way of saying, “Yep, you’re on the intended route, and you’re either approaching or receding from the station accordingly.”

Let’s break down the answer choices and why one option makes the most sense in terms of confirming the VOR system’s accuracy

Here’s the thing about the scenario: you want to confirm that the navigation system is behaving as it should when you’re steering toward a specific course. In that context, the pairing of a TO indication with the correct course is the clearest signal that you’re on the intended path and that the CDI is working as designed.

• A. With a TO indication when selecting 183 degrees (this is the most accurate match)

Why it works: If you set the OBS to 183 degrees and the CDI centers with a TO indication, you’re on the course that leads toward the VOR along that particular direction. In practical terms, you’ve configured a course that points toward the station, and the instrument confirms you’re actually moving toward it on that course. That combination confirms both the course setting and the VOR’s tracking capability.

• B. With a FROM indication when selecting 003 degrees

Why this isn’t the best confirmation here: FROM indicates you’re moving away from the station on the course you’ve chosen. While a centered CDI on a FROM reading does show you’re on the intended course, it’s indicating departure rather than approach. The question and typical teaching emphasis in this area highlight the inward tracking to the station, so this pairing doesn’t provide the same clarity about accuracy toward the station for the specified course.

• C. With a TO indication when selecting 003 degrees

Why this is less direct: A TO reading with 003 degrees would mean you’re on a course toward the station that points at 003 degrees. Depending on where you are in relation to the VOR, that could be correct for certain positions, but the commonly taught pairing for verifying the accuracy of a defined radial uses the inbound or outbound relationship that a larger segment of pilots expect to test with a 183-degree setting. In other words, it’s not the most straightforward confirmation of the requested radial in many practical situations.

• D. When the aircraft is on the radial

Why this isn’t enough on its own: Being “on the radial” means you’re aligned with a particular VOR radial, but it doesn’t guarantee you’ve set the correct course to meet the station’s TO/FROM orientation. The CDI can center while you’re on the right radial, but without knowing whether you’re approaching or departing, you don’t have the full picture of accuracy for the intended path. The TO indication adds the crucial directional context.

A practical way to think about this

Imagine you’re negotiating a dim, calm IFR corridor. You dial in a course that points toward the station, say 183 degrees. If the CDI centers and the display reads TO, you’re convinced that your airplane is indeed cruising toward the VOR along that intended path. You’ve got a strong cross-check that the VOR is tracking correctly, that the course was entered properly, and that the airplane isn’t wandering off into a different direction.

This is far more informative than simply being on a radial or having a FROM indication, because the TO reading explicitly confirms you’re converging on the station along the course you’ve requested. It’s the cockpit equivalent of pulling up to a known landmark and seeing the street sign tell you you’re headed in the right direction.

A few practical notes that help the concept stick

• Always cross-check with a second navaid when you can. If you have a GPS overlay, you can compare the VOR CDI indications with the GPS course to confirm both are telling the same story.

• Remember the reciprocal relationship. If you’re tracking inbound on a given course, your inbound course is often the reciprocal of the outbound radial you’ve set. The key is understanding what the CDI is telling you at that moment—toward or away from the station.

• Don’t get hung up on the exact number. The magic isn’t in hitting the exact degree like a laser; it’s about the CDI centering together with the TO/FROM signal, which validates that you’re on the expected path and that the navigation aids are functioning properly.

• If you ever sense the CDI is centered but your TO/FROM needle seems off, it may be a station passage or a nearby interference issue. In that case, re-check the OBS setting, re-tune the NAV radio, and cross-verify with another navaid.

A quick mental model you can carry into the cockpit

• Centered CDI = you’re on the chosen course relative to the station.

• TO reading = you’re moving toward the station on that course.

• FROM reading = you’re moving away from the station on that course.

• The combination of a centered CDI and a TO reading on the listed course (183 degrees) is the cleanest, most direct confirmation that the VOR system and the selected course are in harmony.

A small digression that helps the concept stay tangible

Navigation on VORs isn’t about precision alone; it’s about trust—trust that the signals your instruments report, the course you set, and the station’s location all align. In the real world, you’ll hear pilots talk about “centering the needle” as a moment of calm. It’s not just a technical milestone; it’s a moment when the cockpit reverts to a simple truth: the airplane is on the intended path, and the instruments back that up. That quiet confidence is what keeps IFR flying so steady, even when the weather or the airspace gets a little rowdy.

Putting it all together in the cockpit

If you’re ever unsure whether your VOR is giving you a truthful read, this is a practical, reliable approach:

• Pick a known course, such as 183 degrees, and set it with the OBS.

• Watch the CDI. If it centers, you’re aligned with that course.

• Check the TO/FROM indicator. A TO reading confirms you’re approaching the station on that course.

• Conduct a quick cross-check with another navigation aid if available, just to reinforce the confidence you’ve gained from the CDI and TO reading.

In the end, the interplay between the CDI centering and the TO indication on a specific course provides a clear, actionable sign that the VOR system is functioning as expected. It’s the kind of crisp, dependable feedback that pilots rely on, step after step, mile after mile.

A closing takeaway

VOR navigation is built on a simple premise: you select a course, the CDI shows how far off you are, and the TO/FROM indicator tells you whether you’re moving toward or away from the station. When the CDI centers on 183 degrees and the display shows TO, you’ve got a solid indication that you’re on the intended route toward the VOR. That clarity—coupled with a few smart cross-checks—gives you the confidence to fly with precision and ease, even when the sky gets a little busy.

If you ever want to chat through real-world scenarios or walk through a couple more example angles and readings, I’m here for it. After all, navigation isn’t just about numbers on a screen—it’s about building a steady sense of direction that you can trust when it matters most.