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?
