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Standards by category (altitudes, limits and restrictions)

When there is no VAC/publication, use conservative standards to reduce the mix of performance in the circuit.

Altitude reference

Use AAL (Above Aerodrome Level), that is, altitude above the aerodrome elevation.

Category Circuit altitude (AAL) Operational notes
Piston (SEP) 1000 ft AAL common standard for light traffic
Jet / high performance 1500 ft AAL reduces conflict with slow traffic; better energy and separation
Helicopters 500 ft AAL (or "low circuit") prefer dedicated routes/areas when possible

Mixed traffic separation

If the traffic is mixed and there are no local procedures, the TWR must separate by altitude and/or by the way it sequences, avoiding "fitting a jet behind a piston" on short final.

Lateral limits (circuit distance)

Category Downwind (lateral distance) Comment
Piston (SEP) 0.8 to 1.5 NM keeping the circuit compact reduces occupancy time
Jet / high performance 1.5 to 3.0 NM more energy, larger turn radius
Helicopters 0.3 to 0.8 NM keep clear of the fixed-wing traffic axis, when applicable
  • Avoid "cutting the base" when there is traffic on downwind/base.
  • Prohibit "straight-in" if it would conflict with traffic in the circuit (unless the TWR can integrate it with separation).
  • Helicopters: prefer a dedicated route (e.g. "via the apron/taxi line", "keeping to the edge of the aerodrome") so as not to cross the fixed-wing final.

Helicopter integration (practical model)

When there is no published procedure:

  • authorise helicopters to operate below the circuit and, when possible, clear of the approach axis.
  • if they need to cross final, do so with explicit coordination and with no traffic on short final.

Local procedures

At aerodromes with heavy operations, the ideal is to create/use a published local procedure. Without one, standardise as much as possible through ATC instructions.