Buzz
VOR, or VHF Omni-directional Range, represents a pivotal radio navigation system tailored for aircraft. VORs emit a VHF radio composite signal that encompasses the station's Morse code identifier, occasionally accompanied by a voice identifier, and crucial data facilitating the derivation of magnetic bearing from the station to the aircraft. Pilots leverage this intel to pinpoint their precise location and chart a course to their intended destination. This discourse presupposes a foundational understanding of aircraft operation.
Procedures
Tuning and Authentication - Set the VOR frequency on the navigation radio, cross-referencing it with VFR and IFR charts, as well as instrument approaches if relevant. Verify the correct station and signal reliability by decoding the Morse code identifier. A red “NAV” or “VOR” flag, barber pole, or OFF indication signals unreliability, while a lack of Morse Code identifier suggests signal instability. A red “GS” flag does not denote VOR indication.
Orienting Yourself - Ascertain your radial position by adjusting the OBS (Omni Bearing Selector) knob until the CDI (Course Deviation Indicator) needle aligns center and displays a FROM indication. Referencing the image above, with the needle centered and a FROM indication (indicated by a small white triangle pointing downwards), the aircraft aligns with the 254-degree radial. Irrespective of the aircraft's current heading, it resides somewhere along the 254° radial line from the VOR station. To navigate towards the VOR station, twist the OBS knob until the needle centers and the white triangle appears adjacent to the 'TO' marker (opposite the 'FR' marker). This corresponds to 074 degrees, precisely 180° from the current radial. Adjust the aircraft to this new heading, maintaining a centered needle to steer towards the VOR station.
Mastering Course Interception
Navigating the Desired Radial - Determine the direction of your intended airway using either VFR or IFR charts. Input the radial's direction into the OBS and adjust the aircraft's heading accordingly. Once aligned, observe the CDI position; right indicates a right radial, left indicates a left radial.
Executing Course Interception - Rotate the aircraft 30 degrees towards the CDI to intercept the course. While 30° is standard, alternative intercept angles are viable depending on distance from the desired course. For extensive deviations, angles exceeding 30° may be necessary for timely course interception.
Following the Radial - Align your heading with the radial as the CDI nears center. Maintain a centered needle to adhere to the radial. Should the needle drift left, adjust your heading leftward to realign with the course. Note that tracking inbound and outbound radials follows identical principles, differing only in indicated direction (TO or FROM). Aircraft heading counter to radial direction may experience 'reverse sensing,' where CDI indicates right for a left radial and vice versa.
Compensating for Wind - If wind causes deviation from the radial, note the deflection amount. Correct by turning the aircraft towards the radial at double the deflection degrees. Upon centering the needle, adjust halfway back to the original heading to establish a wind correction angle (WCA).
Locating an Intersection
Occasionally, you might necessitate pinpointing the convergence of two VOR radials. This convergence could mark a waypoint alteration, transition to intercept another air route, an alteration in minimum altitude for IFR operations, a holding position, or an ATC reporting point. Identifying this intersection entails utilizing two VOR radials or occasionally one VOR radial alongside Distance Measuring Equipment (DME).
Tuning and Identifying Both VORs - Ideally, equip yourself with two VOR receivers; however, even with one, intersection identification remains feasible by toggling frequencies and comparing radial data.
Configuring the OBS - Utilize the OBS to input accurate radials from each VOR. While Victor airways depict radials on VFR and IFR charts, any intersecting radials suffice. On VFR charts, arrows indicating intersections point towards the VOR, whereas on IFR charts, they point away from the VOR towards the intersection.
Awaiting Centered CDI Needles - While tracing one VOR's course, monitor the other to gauge CDI alignment. Once both needles center, you've reached the intersection point. If equipped with DME and utilizing a VOR/DME or VORTAC, DME eliminates the necessity for a second VOR. While tracking the VOR radial, leverage DME to determine your distance from the station. IFR charts display DME distances when identifying intersections. For instance, the WARIC intersection is defined by the 238 radial from the VOR and a 21 nm DME fix.
Pointers
- Opt for a radial within a few degrees of your aircraft's heading to prevent reverse sensing.
- VOR radials are referenced from magnetic north, not true north.
- For IFR flights utilizing a VOR, ensure a VOR check has been conducted within the last 30 days.
