Circuit

The Circuit

The specified path to be flown by aircraft operating in the vicinity of an aerodrome.

Objective

  • How to fly a circuit pattern, leave and enter the circuit.

Why?

  • It’s important to know how to integrate a circuit properly, and how to flight inside it in respect of the rules.

Link

  • Climb.
  • Turns.
  • Descent.
  • Take off.

Review questions

  • What are some factors that affect takeoff performance?
  • What factor usually determines the runway in use at an airport?
  • What are the typical performance charts found in a POH?
  • What is the level off procedure from a climb?
  • What are the causes of yaw?

The circuit: basic theory

  • Unless special conditions exist, all circuit are left hand, therefore all turns within the circuit are left turn.
  • Exceptions occur where traffic conflicts with other airports, or hazardous terrain require the adoption of right-hand pattern, for an entire airport or for specific runways.
  • Unless otherwise authorized, all normal circuit height are 1000 feet above aerodrome elevation.
  • If you need fly over the airport for example to know which runway in use the height will be 1500 feet above aerodrome elevation.

The circuit pattern components

  • Take-off. (Departure leg/upwind)
  • The crosswind leg.
  • The downwind leg.
  • The base leg.
  • The final approach.

Take off

  • Take-off and climb out on runway track to 500 AGL or altitude required for the airport.
  • Control drifting by crabbing into the wind.
  • Check for traffic.
  • Turn to crosswind leg.

Crosswind leg

  • Make a 90 degree turn from upwind to crosswind (Before turning always check traffic ! )
  • Check heading Indicator to correct the drift.
  • Continued climb out to circuit altitude, 1000 ft agl (or as required).

Downwind leg

  • Fly parallel with the intended landing path and at circuit altitude, 1000 feet above aerodrome elevation (or as required).
  • Reduce rpm
  • Trim
  • Check heading Indicator to correct the drift.
  • At the middle of the downwind you perform the pre-landing check.
  • Pre-landing check (check POH):
    • Primer lock.
    • Master on/magneto both.
    • Gauge (temperature/pressure) green.
    • Carburetor on/ mixture full rich.
    • Power 1700 rpm (check POH).
    • Fuel both.
  • Select a touchdown spot on the runway
  • Maintain altitude and let the speed decreasing to Vfe (maximum speed flaps extended).
  • At the end of the runway parallel path you extend 10 degrees of flaps. (reduce stall speed. and steepen angle of descent).
  • YOU STILL MAINTAIN ALTITUDE AT THIS POINT
  • At  45 degrees angle: check traffic and turn 90 degrees to the base leg.

Base leg

  • Fly perpendicular to the runway centerline (may be crab into the wind).
  • Be especially careful to scan and listen for traffic on base or final. Once turned toward the runway, it is difficult to see behind the aircraft.
  • Extend  flaps 10 degrees more (20 degrees total flaps).
  • Begin the descend at 500 feet per minute (or as required).
  • Remember :
    • The pitch control the airspeed.
    • The power control the rate of descent and altitude.
  • Approaching the turn point to final, look out  to ensure the final approach path is clear and check for traffic.
  • Descend to 600ft AGL before turning to final (or as required)
    • If left crosswinds on final, lead the turn.
    • If right crosswinds on final delay the turn.

Final approach

  • Make radio call.
  • Keep the aircraft in line with the runway.
  • Correct for drift.
  • Reduce airspeed to approach speed.
  • Extend flaps a 30 degrees (or as required).
  • Maintain airspeed with pitch and control descent path (rate of descent) with power.
  • When the runway is close extend 40 degrees of flaps (or as required).

Airport/facility directory- Canadian Flight Supplement-etc.

Need to be checked to know the specificities of the airport.

  • Left hand /right hand.
  • Circuit altitude.
  • Obstacles.
  • Etc.

Spacing

  • Be constantly aware of the position of other aircraft circuit.
  • Be careful not to cut off a preceding aircraft by turning onto the base or final leg.
  • Maintain suitable spacing between your aircraft and the one ahead to allow that aircraft time to land and taxi clear of the runway, or land, backtrack and take-off.
  • Correct spacing is a judgment skill you must develop as quickly possible. It takes into account such matters as wind direction and strength, and the circuit speeds of other aircraft.
  • Correct spacing may be accomplished by widening or narrowing your circuit and/or increasing or decreasing airspeed.
  • Sometimes, it may be necessary to execute a missed approach and go around (overshoot).

Radio in uncontrolled airspace.

Aerodrome traffic frequency: ATF
  • ATF frequency will be same as UNICOM or 123.2 MHZ if there is no Unicom.
  • All aircraft listen and report if equipped with a radio.
  • If UNICOM exists, operators will provide information such as:
    • position of vehicles on the maneuvering area.
    • position of other aircraft.
    • runway condition.
    • Airport advisory.
    • Radio check.
Mandatory frequency airport: MF
  • At uncontrolled airport or controlled airport that are not controlled in certain hours.
  • Aircraft must have two way radio.
ATF and MF radio call:
  • Report position, altitude, arrival procedure intentions and estimated time of landing at least 5 minutes prior to entering the area.
  • Maintain listening watch on the ATF while in the area
  • Report joining the circuit pattern giving position in the pattern.
  • Report downwind leg (if applicable)
  • Report established on final approach
  • Report clear of the active runway.
  • Report before entering maneuvering area.
  • Report before moving onto take‑off surface.
  • Report departure from aerodrome traffic circuit.

Uncontrolled airport: Departure

  • Climb to circuit altitude before making any turrns.
  • Turn toward the circuit or back towards the airport should not be made until 500ft above circuit altitude.
  • Check for traffic.

Uncontrolled airport: Arrival

  • Descending at airport elevation altitude from the upwind side.
  • Join downwind leg.
  • If you cross over the field to join mid-downwind, cross at circuit altitude .
  • If you cross over the field to join upwind, cross at least 500 feet above the circuit altitude.
  • If no conflict exists at circuit altitude you can join the circuit straight in downwind leg.

Controlled Airport

To join the circuit:
  • Need clearance prior to entering the zone.
  • Advise control tower about :
    • Identification.
    • Position.
    • Altitude.
    • ATIS (if provided).
    • Estimated distance in miles
    • Direction from the airport.
    • Intentions.
  • The tower controller may provide specific clearances:
    • Join left downwind at circuit height. 
    • Left or right base
    • Straight into final
    • Right downwind
    • Cross overhead the field.
  • Or give you intruction say “cleared to the circuit
    • is expected to join the downwind leg at circuit height.
To Leave the circuit:
  • Advise ATC if you leave or remain within the control zone.
  • Follow the ATC instruction until clear of the zone.
  • Advise ATC of left turn, right turn or straight out departure.
  • Remember :
    • You need a clearance before entering in the runway.
    • You need a clearance before taking-off
    • Except otherwise specified by ATC the circuit will be left-hand.
    • The ATC can delay your turn.
    • Inform ATC when you turn in downwind (or base) and final.

Special VFR

  • In Control Zones VFR pilots can enter when the weather is below weather minima if they receive special permission—referred to as Special VFR.
  • Special VFR is never offered; it must be requested by the pilot.
  • Only available in Class C,D, or E.
  • Two way radio.
  • Pilot must comply with all conditions issued by ATC.
  • The pilot must operate clear of cloud and within sight of the ground at all times.
  • At night, Special VFR will only be authorized for the purpose of landing at a destination airport.
  • Weather Minima for operating in a control zone VFR are:
    • 3 SM VIS
    • 1 SM horizontally and 500ft vertically from cloud
  • If weather drops below minima while Enroute pilot may request Special VFR
    • 1 SM
    • Clear of cloud, ground insight.

Review questions

  • What are the legs of a circuit?
  • What do you need to do before entering a control zone?
  • What procedure should you use to enter the traffic pattern of an uncontrolled airport?
  • What is the difference between controlled and uncontrolled airspace?
  • What are VFR wheather minima for controlled and uncontrolled airspace?
  • What is the altitude above ground in the downwind?