Intercept Angle Challenge
Intercept scenarios at various angles with animated overshoot, undershoot and success.
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Pick an intercept angle — 30°, 45°, 90° or your own — and press Go. The aircraft flies the intercept heading toward the VOR course (its ground track cuts the course at the chosen angle, wind included). Press TURN when you judge the moment: the aircraft turns at standard rate onto the course heading and the run is judged where it rolls out.
Turn too late and the aircraft swings through the course — an OVERSHOOT; too early and it rolls out parallel, short of the course — an UNDERSHOOT; within 0.1 NM is a success. The lead grows with the turn radius (faster aircraft, bigger lead) and with the intercept angle: at 90° the lead equals the radius, at 45° it is about 40 % of it, at 30° about 27 %. Watch the CDI too: the needle starts to move as you near the course — the cue the IFH means by learning to lead the turn.
Learn mode shows the ideal turn point and arc before you fly; Challenge mode hides them until the result. New challenge randomises the angle, side, offset and speed (and the wind when Wind is on). After every run the ideal turn is drawn next to yours, with your timing error in seconds.
Assumption: standard-rate turns (3°/s) with an instantaneous roll-in and roll-out, a constant TAS and wind, one heading frame. The ±0.1 NM success band and the score are training conventions of this platform, not FAA tolerances. In still air the lead is the Lead Radial / Turn Anticipation fly-by lead r·tan(θ/2); in wind the turn is flown in the moving air mass, as in the IFR Trainer’s VOR intercept.
Intercept heading: as in the IFR Trainer’s VOR intercept — ground track = course ∓ angle toward the course, heading from the wind triangle. Roll-out heading = the wind-corrected heading that holds the course (the wind triangle). Turn radius r = TAS / (3600 · 3° in radians) (standard rate, the same as the turn calculators and the trainers).
Ideal turn moment: the straight-leg time of the IFR Trainer’s wind-aware intercept solution (turn in the air mass, ending exactly on the course line). In still air the distance from the turn start to the crossing point equals r·tan(θ/2) — the Lead Radial / Turn Anticipation fly-by lead, and the cross-track distance at the turn start is r·(1 − cos θ); both checked against that tool's own solution.
Judgement: the position and heading at roll-out are computed exactly (straight leg + circular arc in the moving air + drift); roll-out error = its distance from the course; it is linear in your timing error (error = closure rate × seconds late). Overshoot = the roll-out lies beyond the course, undershoot = short of it, success = within 0.1 NM. The animation uses the same function, so the picture ends where the judgement says. Sources: IFH ch. 9 “Course Interception” (angle 20°–90°, lead the turn to prevent overshooting), IFH ch. 4 (rate and radius of turn), AIM 1-2-1 (turn anticipation).
- FAA Instrument Flying Handbook, FAA-H-8083-15B (2012), ch. 9 Navigation Systems — “Course Interception” (interception angle not less than 20° nor greater than 90°; “pilots learn to lead the turn to prevent overshooting the course”)
- FAA Instrument Flying Handbook, FAA-H-8083-15B (2012), ch. 4 Aerodynamic Factors — rate and radius of turn; intercepting at a higher speed requires a longer lead
- FAA Aeronautical Information Manual, para. 1-2-1 — turn anticipation at fly-by waypoints (faa.gov, accessed 2026-10-13)
- FAA Pilot’s Handbook of Aeronautical Knowledge, FAA-H-8083-25C, ch. 16 Navigation — wind triangle: wind correction angle for the intercept and roll-out headings (wind option)
- Cross-tool: Lead Radial / Turn Anticipation — its fly-by lead r·tan(θ/2) equals this tool’s still-air ideal lead
- Cross-tool: the wind-aware VOR intercept of the IFR Trainer’s VOR module, unchanged
- Garmin G1000 Pilot’s Guide for Cessna Nav III, 190-00498-08 Rev. A (system software 0563.30 or later), pp. 56-68 — the glass HSI option (Indicator: HSI (glass)): heading-up compass card, course pointer with a two-dot deviation scale (full scale as on a mechanical CDI for VOR and LOC), green for VOR / LOC and magenta for GPS, flight-phase and OBS / SUSP annunciations, glideslope / glidepath indicator; an equipment example, not a statement about every glass display