Navigation: Units, Charts & Flight Planning
Sharing airspace with crewed aviation means using their language for height, distance, direction and time — and planning before you launch.
Direction & the compass
- Variation is the difference, in degrees, between true and magnetic north at your location.
- Heading is where the nose points; track is the path over the ground; drift is the difference caused by wind.
Units (don't mix them up)
- Height: AGL (above ground level) vs ASL (above sea level). Altitudes are reported in feet.
- Distance: NM (nautical mile ≈ 6,076 ft) vs SM (statute mile = 5,280 ft). Aviation distances use NM.
- Time: the 24-hour clock and UTC ("Zulu", Z); local time is "L".
A classic exam (and radio) trap is 400 ft AGL vs ASL. State it both ways: "operating 400 ft AGL and below, 3,400 ASL."
Charts & references
- VNC (VFR Navigation Chart) and VTA (VFR Terminal Area) charts show airspace, obstacles and frequencies.
- The Canada Flight Supplement (CFS) is the official aerodrome directory.
Flight planning
- Check NOTAMs and weather; confirm weight & balance, documents, and aircraft serviceability.
- Radio theory: most drones use unprotected C2 frequencies, so plan for interference (EMI/RFI) from WiFi, powerlines and other transmitters — lag or video break-up is your early warning of a lost link.
Always review NOTAMs for your area — they flag temporary hazards, closures and other drone or aviation activity you must respect.
Check your understanding
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Key takeaways
- Variation = true vs magnetic north; mind heading / track / drift.
- Use aviation units: feet for height (AGL and ASL), NM for distance, UTC.
- Read VNC/VTA charts and the CFS; check NOTAMs every flight.
- Plan for interference on unprotected control links.
Sources: RPAS 101 pp.61–63, 46–48, 115 · TP‑15263 §5 (Navigation, Basic topics).