Obstacle marking & lighting
Object of any height meeting one test in CAR 601.23(1) is an obstacle to air navigation, must be marked and/or lit to CAR Standard 621 (TC AIM AGA 6.1).
Triggers (TC AIM AGA 6.2):
| Trigger | Threshold | Cite |
|---|---|---|
| Penetrates airport Obstacle Limitation Surface (OLS): approach, take-off, transitional surfaces | Any penetration | AGA 4.2.1, 6.2(a) |
| Object near aerodrome | Over 90 m AGL, within 6 km of aerodrome geographic centre | 6.2(b) |
| Object near recognized VFR route (valley, railroad, transmission line, pipeline, river, highway) | Over 90 m AGL, within 3.7 km of route centreline | 6.2(c) |
| Permanent catenary wire crossing | Any part of wires or supports over 90 m AGL | 6.2(d) |
| Any object, anywhere | Over 150 m AGL, no proximity test | 6.2(e) |
| Other object Minister deems hazard | By height or location | 6.2(f), CAR 601.25 |
Day marking (TC AIM AGA 6.4):
| Structure | Marking |
|---|---|
| Obstructions 150 m AGL or less (poles, chimneys, antennas, cable-tower supports) | Alternate bands of aviation orange and white paint |
| Water tanks | Checkerboard pattern |
- Paint can be omitted if structure has medium- or high-intensity white flashing strobe lighting operated during the day.
Lighting (TC AIM AGA 6.5):
- Purpose: warn pilots of collision risk.
- Intensity lets pilot recognize light and still take evasive action, clearing obstruction by at least 600 m.
- Acquisition distance:
| Speed | Distance |
|---|---|
| 165 KIAS | 1.90 km |
| 165 to 250 KIAS | rising to 2.4 km |
Trap: 90 m AGL needs proximity (aerodrome 6 km, VFR route 3.7 km, or catenary crossing); 150 m AGL is the only height trigger with no location test. Also, 600 m is evasive clearance, not the 1.90 km or 2.4 km acquisition distance behind it.
References
- CARs 601.23(1)
- CARs 601.25
- TC AIM AGA 4.2.1
- TC AIM AGA 6.1
- TC AIM AGA 6.2
- TC AIM AGA 6.4
- TC AIM AGA 6.5