Intercepting and tracking courses

Orient before selecting the intercept

Begin with the clearance or procedure: which facility or waypoint, which course, inbound or outbound, and which altitude and speed requirements? Then verify usable equipment, the actual navigation source, identification or programmed path, course, TO/FROM or active-leg information, validity and sensitivity. Use the published restrictions, required checks and installed manuals. Do not start with a needle deflection and invent a destination afterward.

Establish position relative to the desired line. For VOR, a centered FROM course identifies the radial; the inbound course is its reciprocal. On GPS/RNAV, verify the active from/to leg and desired track. A map is useful for orientation when its data are valid, but the selected leg must still match the clearance. A Direct To path may reach the same waypoint by a different line.

Say the picture in words: “I am south of the east-west line, and I need to travel west inbound.” This determines which side you must cross toward before a heading is chosen. Check the course selection so conventional VOR sensing agrees with the intended direction. HSI geometry can help show the line and the crossing angle, but it cannot correct a wrong source or route entry.

The preceding VOR equipment-check section, display source/mode checks, and GPS path verification supply the system checks used here. This lesson applies them to flightpath decisions.

IFH 9-14–9-16: orientation, course selection and interception · AIM 1-1-17: programming and verifying GPS paths · ACS V.A, printed page 12

Choose a crossing heading appropriate to the geometry

An intercept angle is the angle between the intended course and the track used to cross toward it. An intercept heading combines that geometry with wind. A larger crossing angle normally reaches the line faster but creates more closure and a sharper transition at capture. A smaller angle is often easier to capture close to the course, provided it still overcomes drift and crosses toward the line.

The appropriate choice depends on displacement, distance from the facility, groundspeed, wind, turn capability, traffic and procedure protection. A full-scale VOR needle tells you you are at least the full-scale angular displacement; it does not reveal the exact distance from the line. Determine position before applying a formula. A clearance or vector specifying a heading also constrains the choice; do not substitute your preferred intercept without appropriate coordination.

The IFH provides introductory intercept-angle methods, including doubling angular difference within a stated range. These are techniques for an oriented training problem, not universal requirements. Choose a sensible angle with your instructor and the actual aircraft, then monitor closure rather than assuming a rule guarantees capture. Close to a VOR or a sensitive final course, a steep intercept with high groundspeed can produce a quick overshoot.

IFH 9-14–9-16: interception angles and closure/lead · ACS V.A, printed page 12

Work inbound and outbound from the position picture

Inbound example: an identified valid VOR places you on its 095° radial, south of the 090° radial. You want 270° inbound along that 090° radial. Select 270° and verify TO. With no wind for this initial study problem, heading 300° crosses northwest toward the desired line at a 30° angle. The CDI is right when interpreted facing 270°; a heading 240° would cross southwest away from the line.

As the needle moves toward center, prepare to turn left from 300° toward 270° with appropriate lead. Confirm capture and the actual track before settling into the tracking correction. The point is the selected path and crossing direction, not that every inbound intercept should use 300° or 30°.

Outbound example: you are northeast of a station on its 080° radial and want to intercept 090° outbound. Select 090° and verify FROM. The desired eastbound radial lies south of your position. In the no-wind problem, heading 120° crosses southeast toward it at 30°. As the line approaches, a left turn toward 090° captures it. Heading 060° would move northeast away from the desired line.

Use a north-up sketch to check both examples. Change only the airplane’s nose direction at a fixed position: the VOR position/course relationship stays the same. Then move the airplane: deviation changes. This separates heading control from position interpretation. Use the navigation trainer if available, but draw and explain the same geometry on paper.

IFH 9-11–9-16: heading independence and course interception

Observe closure and start the capture turn in time

During the intercept, maintain the selected heading and appropriate aircraft performance while watching the needle’s direction and rate of movement. A needle moving toward center indicates closure. Rapid movement suggests less time to complete the turn; a static needle can mean a parallel path, inadequate correction for wind, or a setup/source problem. Cross-check the position picture instead of waiting indefinitely.

Because a turn takes time and distance, waiting for exact needle center before beginning every capture can overshoot. Lead the turn according to actual closure, groundspeed and turn response. Close to a VOR, the same lateral movement produces faster angular needle travel. On localizer or changing GPS scale, sensitivity also affects the displayed motion. Avoid a fixed “turn at one dot” rule without context.

If you overshoot, recognize it promptly. Preserve altitude, airspeed and control, orient to the other side of the line and select a suitable correction. Do not alternate large banks with every needle movement. Reassess an excessive angle, high speed, wrong course/source or unexpected wind. If the deviation threatens procedure compliance or exceeds your capacity, coordinate with ATC as appropriate rather than forcing a hurried capture.

A centered instant is not established tracking. After rollout, compare heading, track and the developing deviation. Capturing the line is the transition between the crossing heading and the wind-corrected heading that keeps you on it.

IFH 9-14–9-16: closure, lead, overshoot and overcontrol · AIM 1-1-18: WAAS scaling changes · ACS V.A, printed page 12

Distinguish recapture from the correction that holds course

Once near the line, use a heading that maintains the desired track rather than automatically matching the selected course. If the needle slowly drifts away after capture, identify the displacement direction and add a suitable correction into the drift-causing wind. A temporary recapture heading usually needs a larger angle than the eventual holding correction. Reduce it as the line is regained, then observe the next trend.

Worked bracketing example: on an invented 270° inbound leg, heading 270° allows southward drift and a right CDI deflection. Heading 280° crosses back toward the line. Near capture, reduce to 275° and observe: if southward drift resumes, more northward correction may be needed; if you drift north, reduce it. These trial headings explain the technique only. Actual headings depend on wind, groundspeed and response, and must remain appropriate for the operation.

Bracket a useful correction with progressively smaller adjustments. Hold a chosen heading long enough to observe a meaningful trend, while continuing the scan; do not change it continuously to chase the needle. Wind may change with altitude, location or the curve of an arc. An electronic track indication can assist if reliable, but keep comparing position, path and guidance validity.

Keep the selected course fixed when tracking a specified VOR course. Continually turning the OBS to center the needle and flying each new indicated course turns tracking into homing, which can produce a curved path in crosswind. Center the airplane on the desired line, not the selected line on the airplane. On GPS, similarly preserve the cleared active path instead of repeatedly replacing it with Direct To.

IFH 9-14–9-16: tracking, bracketing and homing errors · ACS V.A, printed page 12

Anticipate passage and the next leg

Near a VOR, angular sensitivity increases and the cone of confusion can make indications unstable. Maintain the appropriate established heading through passage rather than chasing rapid needle swings. Cross-check expected position, positive TO/FROM transition and available distance trend. After passage, verify the next outbound course and any required station/source change.

For GPS/RNAV, watch the active leg and sequencing, not just distance approaching zero. A fly-by waypoint permits appropriate turn anticipation; a fly-over waypoint requires crossing before the next-leg turn. A waypoint can have a different role in another segment. Follow the chart and coded procedure, and manage any suspend/vector/manual-termination condition according to the installed guidance.

Prepare the next course, source and modes before transition becomes urgent. A map can show route progress and drift, but it may share a failed GPS position and can hide a wrong active leg under a plausible route drawing. Check the path-driving indications alongside the picture. A frequency change must include identification of the new aid and verification that the CDI, DME and autopilot use the intended sources.

IFH 9-14–9-16: VOR station passage · AIM 1-1-17: waypoints and sequencing · IPH Chapter 6, printed 6-4–6-8: fly-by/fly-over and manual termination

Include the whole flying task

DME arcs require the same capture, trend and wind-correction reasoning with a continuously changing tangent direction. Verify the specified facility or suitable approved RNAV reference, use distance and radial progress together, lead the entry and exit appropriately, and correct inside/outside deviations. Review the DME arc correction lesson before instructor-led practice.

For ACS V.A navigation systems, flight preparation targets include airspeed within ±10 knots, altitude within ±100 feet and selected headings within ±5°. Course tracking permits no more than ¾-scale CDI deflection; if a DME arc is selected, its distance must be maintained within ±1 NM. These are the actual standards for this Task, not the different heading tolerance from another instrument-flight Task. They are not planned deviations or a promise of obstacle clearance.

Navigation attention must not hide a descending altitude or decaying airspeed. Continue attitude, power and performance checks through intercepts, turns and programming. Use appropriate small coordinated control changes, monitor trends and trim as required by the aircraft. A neat map trace does not establish safe aircraft control.

This lesson teaches the reasoning and briefing behind those standards. An interactive needle or a correct quiz answer cannot demonstrate them. Practice actual equipment operation, capture, tracking and performance with an instructor under the required training conditions, then debrief both navigation and control.

IFH 9-17–9-19: arc application · ACS V.A, printed page 12

Confirm capture and supervise the coupled path

If the installed autopilot is approved and used for the operation, verify the correct source and path, relevant heading/course selections, and armed/active guidance modes. A heading mode may establish the intercept while NAV is armed; the exact capture logic and angle limits depend on the installation. Read the actual supplement rather than assuming every system captures the same way.

Monitor mode annunciations and actual response through capture. A centered needle with NAV armed does not prove capture; a NAV-active indication does not prove that the programmed leg matches the clearance. Compare the track, course deviation and altitude/airspeed with the intended operation. Be ready to use an appropriate simpler mode or manual control under the approved procedures if guidance becomes unsuitable or automation behaves unexpectedly.

Example: you expect a 270° course capture but the active GPS leg remains Direct To on 245°. The autopilot can capture 245° correctly. Fixing that situation requires the correct authorized path and mode verification, not blaming the autopilot for following its selected input. Keep controlling the airplane during the correction and obtain ATC clarification or a revised clearance if needed.

ACS V.A.S9 permits evaluator-discretion autopilot intercepts if installed. Knowing how to couple guidance is part of preparation, while the practical test and instructor-led training establish the actual skill. Automation reduces some control workload only when its operation is understood and monitored.

AIM 1-1-17: installed navigator familiarity and proper use · ACS V.A, printed page 12

Respond to invalid guidance before it controls the flight

A navigation flag, lost integrity, missing/wrong identification, a known unusable facility, unexpected position jump or persistent disagreement with independent evidence calls for assessment. First maintain aircraft control on reliable flight references. Stop using suspect guidance for the affected operation, including inappropriate autopilot coupling, and follow AFM/POH and approved supplements for reversion or failure actions.

Verify selections and determine what capability remains. Two displays fed by the same receiver do not create a second navigation system. GPS substitution for conventional aids depends on suitable approval and current AIM restrictions; an available distance or map is not universal authorization. Seek a usable independent source, conventional route or suitable approach as appropriate to the actual aircraft, fuel, terrain, weather and clearance.

While IFR in controlled airspace, report in-flight navigation-equipment malfunctions to ATC as soon as practical under §91.187. Include aircraft identification, affected equipment, the impairment and desired assistance. For GPS interference, apply the current AIM known NOTAMed testing exception unless assistance is needed. Request vectors, clarification or another appropriate clearance when necessary; communicate actual capabilities rather than “navigation failure” alone.

Use single-pilot resource management: keep control first, organize and prioritize entries, brief the next transition, and use ATC or appropriate trained help. If operating with another qualified pilot, assign duties clearly and verify important changes together. The available resources must preserve control and an accurate position picture, not add simultaneous competing tasks.

AIM 1-1-1: unusable transmitter indications · AIM 1-1-17: integrity and alternate navigation · AIM 1-2-3: substitution limits · AIM 1-2-4: interference and reporting · 14 CFR §91.187: IFR malfunction report · ACS V.A, printed page 12

Brief, fly the reasoning, and debrief the cause

Written training exercise: use the inbound 095° radial example with 270° selected TO, an appropriate initial intercept, and a steady wind that causes southward drift. Targets are invented for study; use the aircraft’s actual settings in training. Before simulating motion, explain position, desired path, source, validity, scale, intended intercept and performance priorities.

1. Approach the line: hold the planned intercept heading and include altitude/airspeed in the scan. Increase attention to closure as the needle comes in.
2. Capture: lead the turn according to observed closure. Check track and deviation after rollout; choose a trial wind correction, then refine it from trends.
3. Transition: describe expected VOR passage and the next course/source. If using GPS, verify the coded transition and sequencing state.
4. Introduce a failure: invalidate the guidance. State how control is maintained, which installed procedure applies, what navigation remains, and what ATC assistance is needed.
5. Debrief: identify whether any error began with setup, orientation, intercept angle, lead, wind correction, source/mode, distraction or flight control.

Use the trainer’s positions and heading changes if available, or sketch the same states on paper. Explain what each change means before selecting a new heading. The instructor-led flight lesson will add actual equipment manipulation and verify the ACS performance standards.

IFH 9-14–9-19: intercept, tracking and arc techniques · ACS V.A, printed page 12