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  • Circuit Tutorial 

    This document is a brief tutorial on conducting circuits, primarily from a pilot’s point of view, however it may also be helpful for controllers. Note: This document is designed to be used for VATSIM, specifically within Australia. This document is NOT to be used for real training purposes.

    What are circuits?

    A circuit is a routinely practiced procedure that involves departing from an aerodrome, making some turns to form the ‘circuit pattern’ and landing on the same runway you departed from. Circuits are a great way to practice takeoffs, landings, maintain straight & level flight, as well as climbing, descending and turns (with a combination of both), remembering pre-landing checklists off by heart, all of this whilst talking to Air Traffic Control. 

    Things we need to be aware of being conducting circuits

    -  Circuit direction: By default, the circuit direction is to the left of the active runway (Anti-clockwise). This is because the pilot in command typically sits in the left-hand seat and therefore will give the pilot the best visibility of the aerodrome’s active runway, as it should be in sight at all times. If it is not to the left, it will be stated under ERSA for that aerodrome which can be found on Airservices AIPs online.

    -  Circuit & overfly height: Unless otherwise specified by ERSA, the circuit height is 1000ft above aerodrome elevation.  Overfly height is an extra 500ft above the circuit height. These heights shall be rounded to the nearest 100ft. For example, if you have an aerodrome elevation of 434ft, the circuit height will be 1400ft & the overfly height will be 1900ft. One reason overfly height is used is if pilots are flying a visual departure and want to depart the aerodrome in a direction other than the circuit, they may do so by climbing to ‘overfly’ height. This allows them to track overhead the aerodrome. Note: Circuit height can differ based of the aircraft performance category. 

     

    Type of aircraft

    Standard circuit speed

    Standard circuit height

    High performance - (includes jets and many turboprops)

    Above approximately 150 kt

    1500 ft above aerodrome elevation

    Medium performance - (includes most piston engine aircraft and gliders)

    Between approximately 55 kt and 150 kt

    1000 ft above aerodrome elevation

    Low performance - (trikes and ultralight aircraft)

    Approximately 55 kt maximum

    500 ft above aerodrome elevation

    3___non-controlled-aerodromes___circuit-procedures___Circuit_procedures.png.a220387d0207de3d4cde328de8a8beac.png

    Source: VFRG by CASA

    -  Traffic levels: In VATSIM, often people will choose to fly circuits at bigger and busier aerodromes, particularly ones with lots of RPT (regular public transport) because it is more likely that there will be ATC online. It is recommended to use tools such as VATSpy before commencing circuits at larger airports to see if traffic levels are low enough for that aerodrome. This reduces delays and stress for both other pilots, and the controller (If there’s one online)

    -  Suitable weather condition and remaining in VMC (Visual meteorological conditions): You are pilot in command! It is your responsibility to ensure that the conditions you are about to fly into are acceptable. Be sure to read the TAF for the aerodrome you plan on flying circuits at. As well, listen to the ATIS and note the weather conditions. One thing in particular to be aware of is the aircrafts maximum demonstrated crosswind component. Make sure that if there is any crosswind present (or forecasted), it is within the aircraft’s limits. As mentioned previously, the aerodrome and specifically the active runway must be in sight at all times. So, you MUST be flying VFR. (SVFR) is also permitted but will not be covered in this tutorial. Below is a table of what is considered VMC depending on airspace classes.

    Airspace class

    Visibility

    Cloud

    C - At or above 10,000ft AMSL  

    8km

    1500m horizontal 1000ft vertical

    C - Below 10 000 ft AMSL

    5000m

    1500m horizontal 1000ft vertical

    1313092941_3___general-information___visual-meteorological-conditions___VMC__controlled_airspace__Class_C.png.fa734e1d21f099c46d7643119387ecd6.png

     

    Airspace class

    Visibility

    Cloud

    D

    5000m

    600m horizontal, 1000 ft vertically above cloud; or 500ft vertically below cloud

    346665801_3___general-information___visual-meteorological-conditions___VMC__controlled_airspace__Class_D.png.ad1126b2ebdeb7ab71b2222f9baf8da3.png

     

    Airspace class

    Visibility

    Cloud

    E - At or above 10,000ft AMSL

    8km

    1000ft vertical 1500m horizontal

    E – Below 10,000ft AMSL

    5000m

    1000ft vertical 1500m horizontal

    1649477989_3___general-information___visual-meteorological-conditions___VMC__controlled_airspace__Class_E.png.1dcc516d13988780ba41b73108ce6c90.png

     

    Airspace class

    Visibility

    Cloud

    G - At or above 10,000ft AMSL

    8km

    1000ft vertical 1500m horizontal

    G – Below 10,000ft AMSL

    5000m

    1000ft vertical 1500m horizontal (In class G, clear of cloud below 3000ft)

    1576874818_3___general-information___visual-meteorological-conditions___VMC__non-controlled_airspace__Class_G_1.png.13f000d1aa242c5da42f6b04b48be1f9.png

     

    Source: VFRG by CASA

    How do we fly circuits?

    It is important that we have an understanding of the 5 legs of the circuit. Below is a diagram of these legs with the relevant names.

    Note: In diagram, circuit direction is to the left

    CIRCUIT_DIAGRAM.thumb.png.c909134d407103e0cfcaaca781203d44.png

     

    Note: The name of the circuit legs is in relation to the runway. They are NOT in relation to the actual wind direction. The idea is that you will primarily be departing on the active runway into wind.

    __________________________________________________________________________

    Start clearance: Before commencing circuits, make sure to request engine start clearance from ATC for circuits. This is done to prevent wasting fuel if there are any delays. To request start clearance from ATC, turn on your battery master and avionics, then tune to the appropriate frequency. “Melbourne tower, Cessna Alpha Bravo Charlie for circuits request start.” Reply to ATC as required

    Upwind: Once we are cleared for takeoff and airborne, we will be flying the ‘upwind’ leg. All this requires us to do is to keep tracking the runway extended centreline as well as flying at the aircrafts best rate of climb (Vy). Keep in mind to compensate for any crosswind. It is super important that you do not end up being blown off track, especially if you are flying at an airport where there are parallel runway operations in progress. For example, you are conducting circuits on runway 34R at Sydney, if you have a strong wind blowing from the east, without proper correction, you will be blown off track and potentially drift over to runway 34L. Fly the upwind leg until 500ft AGL.

    Crosswind: You are climbing on the upwind leg, once you reached 500ft AGL, you may commence a climbing turn (around 15° bank) to fly the ‘crosswind’ leg. Continue the climb.

    Downwind (and radio call): As soon as you level out at 1000ft AGL on the crosswind leg, you may begin a medium level turn to join downwind (around 30° bank). In most cases, this will create a good distance between the active runway and the downwind leg. Keep in mind however that you may need to extend the crosswind leg or turn downwind earlier than 1000ft AGL to create a reasonable circuit size. Factors such as wind, aircraft type and other circuit traffic might require you to eyeball how wide to fly the circuit. ATC prefer to know your intentions as early as possible. Subject to workload, mid-way through your turn onto downwind is ideal. However, making the call once established on the downwind leg is also acceptable. Each time you turn downwind, you need to let the tower know whether you would like to continue flying circuits “touch and go” or make it your last one “full stop”. The downwind call should go something along the lines of. “Alpha Bravo Charlie turning downwind, touch and go”. If you are the next aircraft to receive landing clearance, the tower will then reply with “Alpha Bravo Charlie number 1”. All you need to read back is your callsign. After you have made your call, it is good habit to get all of your pre-landing checks out of the way, because you aren’t in the air for that long. It helps if you can memorize the pre-landing checklist.

    Base: Again, depending on circuit traffic or instructions by ATC. Start making a medium level turn to join ‘base’ when you are around 45° from the runway threshold (as shown in diagram). Whilst you are turning onto base, you can start your descent. In this time, keep a listen out for ATC to give you your landing/touch & go clearance.

    Final: Make sure you are turning onto final no less than 500ft AGL. If you need to go around for whatever reason. Advise the tower as soon as practical. If you overshoot the centreline, don't worry! don't try to correct this with more angle of bank. Instead continue your turn back towards the centreline and line up.

    Touch & go: Once you have touched down, assuming you have received your touch & go clearance from the previous circuit, retract your flaps, advance to full power and lift off at the aircrafts rotation speed (Vr). Be mindful if you are flying at an airport with a shorter runway length, you do not have much time to keep rolling down the runway, especially if you touched down further than planned.

     

    Thanks to @Will Menzies for writing this tutorial!

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