Circuit training

This lesson covers vacating and joining at controlled and uncontrolled aerodromes.

The standard overhead join procedure is the preferred/default method for joining the traffic circuit at an unattended aerodrome, where no other method is published. It is used when the pilot-in-command needs to assess the runway in use, familiarise themselves with the aerodrome traffic and conditions, or when required by ATC.

The Standard overhead join poster is a good resource for this briefing. You can request a copy by emailing publications@caa.govt.nz.

Objectives

To vacate and join the circuit in accordance with applicable procedures.

To join an uncontrolled circuit in accordance with the standard overhead join procedure.

Considerations

Discuss vacating the uncontrolled aerodrome first. As with many aspects of safe flying, ground preparation is key to less pressure for the pilot in the air. With a clearance, these methods are also available at controlled aerodromes.

Be aware that helicopters may either conform to the circuit "or avoid the aerodrome traffic circuit being used by an aeroplane operating on or in the vicinity of the aerodrome". Therefore, they will either be sequencing in the pattern, or joining in a manner to prevent conflict with existing traffic. (CAR 91.223)

This rule also exempts agricultural aircraft performing an agricultural operation from conforming with the circuit pattern, but only when a ground symbol is used to indicate this.

The standard overhead join provides a predictable procedure for aircraft (both NORDO and radio equipped) to join the circuit with situational awareness of each other's movements.

Uncontrolled aerodromes

Vacating

Leaving the circuit at an uncontrolled aerodrome is usually done from one of the circuit legs, climbing straight ahead on the runway heading, or from crosswind or downwind, or climbing to overhead – remembering that turns are always in the circuit direction. If intending to turn other than the circuit direction, you need to fly clear of the circuit (2 NM or greater than 1500 ft AGL) before making the turn.

If operating a high-performance (speed or climb) aircraft with traffic joining that may be about to cross the upwind threshold, it is best to delay the take-off. Alternatively, manage the climb to pass through the upwind threshold below 1000 ft AGL clear of joining traffic.

Standard overhead join

Rule 91.223 Operating on and in the vicinity of an aerodrome requires the pilot to "…observe other aerodrome traffic for the purpose of avoiding collision, and, unless otherwise authorised or instructed by ATC, conform with or avoid the aerodrome traffic circuit formed by other aircraft." The standard overhead join procedure is the recommended means of complying with this rule, by being 500 feet above aerodrome traffic and then sequencing appropriately.

At an unattended aerodrome there will be no ATC instructions, and there may be no ATIS or AWIB to forewarn the pilot of the runway in use and wind conditions.

If the aerodrome is listed in AIP Vol 4, circuit direction will be shown on the aerodrome chart. All circuit directions are left hand unless a curved right-hand arrow is displayed at the threshold depicting a right-hand circuit. This information and an estimate of the surface wind can provide a clue to the circuit direction.

Even if the runway in use is known, the pilot should carry out the standard procedure if they are unfamiliar with the aerodrome layout and unsure of the location of other traffic.

The term 'overhead' is used because the aircraft is flown over the aerodrome at a safe altitude above the circuit to look down and determine which runway is in use, or most suitable, to sight any traffic, and manage the safe sequencing with existing traffic.

It's important to realise that there may be traffic without a radio, NORDO (non-radio), and your only method of avoiding collision with them is to sight them and work out what they are doing from their position and movements. That is why both NORDO and radio equipped aircraft must conform to predictable, standard procedures, including right-of-way rules, ensuring a high level of situational awareness and the ability to sequence without causing conflict.

Discuss the information found on the aerodrome chart that is applicable to the standard overhead join procedure. This includes: aerodrome elevation; runways available and their suitability; circuit directions; specific aerodrome instructions; the location of windsocks; and how to hold the chart to aid orientation. If the aerodrome is unfamiliar to the student, a study of the aerodrome chart should be carried out before flight.

Unless otherwise stated on the aerodrome chart, the standard overhead join is generally the joining procedure used by NORDO traffic.

If the aerodrome chart includes a parachute landing area symbol, caution should be exercised, because most landing charts where parachuting takes place advise against the use of a standard overhead join. This is also a factor where glider winching occurs.

In both cases, when approaching the aerodrome, anticipation of using a standard overhead join procedure is appropriate. If on making a joining call it becomes apparent that parachuting or winching activity is in progress, then the runway in use may be advised or is clear. In such cases it is then prudent to join downwind, base or final. If you arrive overhead without indication of either activity, then situational awareness by all parties should permit completion of the overhead join to at least the downwind position before parachutes or gliders are launched.

Discuss the requirement to terminate the flight plan with ATC after landing at uncontrolled aerodromes.

Simulating a standard overhead join by 'walking and talking the pattern' beforehand can be useful to prepare the student for this exercise.

If the cloud base prevents an overhead join, then still approach the aerodrome with the field on your left, but remain clear of the circuit by positioning greater than 2 NM out and flying around the circuit pattern looking to your left to confirm the wind and ascertain any traffic before joining on either the downwind, base or final leg.

Controlled aerodromes

Vacating

When vacating a controlled aerodrome, all of the previously mentioned options are available. In addition, a clearance to turn in the opposite direction to the published circuit may be given by ATC, or requested by the pilot. If a non-standard clearance is required, keep a good lookout and request it before take-off.

Joining

When joining at a controlled aerodrome, the pilot-in-command has the option of requesting a standard overhead join. This is a good idea if the pilot is unfamiliar with the aerodrome layout, the active runway, or the position of the various circuit legs. ATC also has the option of instructing the pilot to carry out a standard overhead join.

However, the most common method of joining at a controlled aerodrome is to be cleared by ATC to join on the downwind, base, or final approach legs. Such a clearance may be for an aerodrome traffic circuit opposite to the published circuit for that runway; for example, "join right base" for a runway with a left-hand circuit.

Another possible clearance is to "cross overhead and join downwind". This is not a standard overhead join.

It's good aviation practice to establish the aircraft on an extension of the circuit leg to be joined, well before reaching the circuit area.

Where ATC is in attendance, but ATIS is not available, common practice is to request joining instructions. ATC will inform the pilot of the conditions and clear the pilot to join the circuit in the most appropriate way.

When ATIS information has been received before reaching the reporting point for circuit joining, the pilot should state or request from ATC the preferred method of joining.

A clearance to join downwind, base, or final does not absolve the pilot from giving way to other aircraft already established in the circuit.

Aerodrome Flight Information Service

Where an aerodrome flight information service (AFIS) is provided, joining and departing procedures specific to that aerodrome will apply. This may include the standard overhead join.

When joining at an aerodrome with AFIS a radio call at 5–10 miles (or a position determined by the airspace) is required to state your position, altitude, intentions and POB. The AFIS will advise the ATIS, QNH and traffic information. The arriving aircraft then advises more specific intentions based on the information received.

Airmanship

Preparing the aeroplane for arrival involves the use of AIP Vol 4, the VNC (Visual Navigation Chart 1:250 000 or 1:125 000 if applicable) and joining checklists.

Revise CAR 91.229 right-of-way rules and emphasise the requirement to make turns in the circuit direction.

Good airmanship dictates that wind awareness is always important. Continually observing any available wind cues, least of all drift, should mean that before joining, the wind can be reasonably anticipated.

If a downwind leg will not be flown, the aeroplane is prepared for landing before circuit entry by using joining and prelanding checks.

There is a tendency for the student to rely on radio calls during the overhead join, and to make too many. It is critical that a good lookout is carried out to identify all aircraft operating in the circuit, including those without radios.

The overhead joining procedure is used to determine the runway in use, and the position of traffic, in order to sequence safely. It does not presume a right of way over existing circuit activity. It may be necessary to remain in the overhead pattern, 500 feet or more above circuit height, until safe sequencing is available.

If potential conflict with other overhead traffic is likely, vacate the overhead and continue (wings level) to a point beyond the circuit area (approximately 2 NM) and turn left to return to overhead the aerodrome at or above the joining height to reassess.

When joining at an unattended aerodrome where an IFR approach may be conducted, it is important to understand and apply the right-of-way rules. If the IFR aircraft is not visual, it will be descending in cloud and be unable to see you or amend its position. It will typically call at least 4-8 NM out as “on long final” which means if you are downwind it would be prudent to extend until you sight the aircraft when it becomes visual.

Aircraft management

Before entering the circuit, the aircraft's speed will need to be reduced to below 120 knots, where applicable, as circuit speeds are normally restricted to this.

The landing light should be on.

Joining checks should be completed.

Human factors

As the student is positioning overhead, encourage them to get oriented by using the aerodrome chart and wind socks for indications of runway in use.

The limitations of vision are revised in relation to closure rates and objects that do not produce relative movement.

There is a lot of information to take in while approaching and circling overhead. Encourage the student to approach it systematically.

Build and maintain situational awareness of other traffic, including surface activity and runway conditions.

Air exercise

Vacating

Discuss the way you would normally vacate your home aerodrome circuit, and the way you would vacate other types of aerodrome.

Uncontrolled aerodrome joining

When joining at an unattended aerodrome, a radio call addressed to the circuit traffic is made between 5 and 10 NM from the aerodrome, stating your position (using VRP, prominent feature, or distance and compass direction), altitude, and intentions. If the first call is made some way out, it may be prudent to make a second call closer in as aircraft on the ground may have just started up and not heard the first call.

The standard overhead join procedure is carried out in three main phases.

Standard overhead join

Approach

Approach the aerodrome to cross overhead at not less than 1500 feet above aerodrome level (refer landing chart) unless otherwise stated on the landing chart; for example, at Palmerston North 1500 feet AMSL is used because of airspace above.

When calculating the altitude to join overhead at, round up – assuming there is no overlying airspace restriction. For example, if aerodrome elevation is 150 feet, join altitude would be 1650 or 1700 feet, not 1600 feet. The reason for rounding up is to maintain a 500-foot buffer over aircraft in the circuit, which may have rounded up the circuit altitude. At altitudes above 1500 feet, it is harder to distinguish the windsocks, and more altitude will need to be lost on the descent. In addition, if all aircraft join at the same altitude it should be easier to see each other.

Effort should be made to identify the wind before arriving at the aerodrome by observing cues such as drift, wind shadow on stationary water, trees, smoke, dust, forecast wind, etc, to anticipate the into wind vector.

On approach, position the aircraft with the aerodrome to the left, so that the student can look out of their window, down and across the whole aerodrome, observing traffic, windsocks and ground signals or markings.

Determine runway in use

Firstly, the student must determine (if aware of the wind direction, then confirm) which runway is in use, as this sets which direction to make all turns, and the traffic and non-traffic sides.

The runway in use can be worked out by observing the windsocks, or other traffic already established in the circuit. If the runway in use cannot be determined, make a turn to the left and remain in the overhead pattern until it is determined. If it is then found that a right-hand circuit is in use, continue to the non-traffic side positioning to make all further turns to the right. If a right hand pattern is required, depending on existing traffic, either veer left on crossing the threshold to allow sufficient room during the turn to the right to descend to circuit height before again crossing to the traffic side, or fly wings level clear of the non-traffic side to reposition in a right pattern.

Note that windsocks are generally sited on the left near the threshold of each vector. On smaller airfields, if there is only one windsock it will generally be centrally placed. If there are crosswind vectors without windsocks at each end, again there will generally be a centrally sited windsock.

If potential conflict with other overhead traffic is likely, vacate the overhead and continue (wings level) to a point beyond the circuit area (approximately 2 NM) and turn left to return to overhead the aerodrome at or above the joining height to reassess.

Be aware that some aerodromes have alternate circuit patterns for helicopter and glider traffic. If they are in use, joining aircraft must sequence into the circuit without causing conflict.

Both the traffic and non-traffic side must be identified to avoid descending onto aircraft already in the circuit. One method of identifying the traffic side is to have the student imagine they are lined up on the chosen runway ready for take-off. If they were to take-off which way would they turn at 500 feet – this establishes the traffic side.

Once the runway in use has been established and the circuit direction is confirmed (refer landing chart), a turn is made in the circuit direction to position the aircraft on the non-traffic side. As aerodromes are potentially areas of high traffic density, use no more than a medium angle of bank. At this point it is good aviation practice to make a radio call advising traffic of the runway you are joining for.

Aircraft already in the circuit have right of way. This means that if aircraft in the circuit are using a runway considered unsuitable for your operation, the responsibility of avoiding conflict is on the joining aircraft, even if the runway in use is out of wind.

Regardless of which way the aircraft is turning, the turn is continued until the centreline of the runway in use is crossed, and the aircraft enters the non-traffic side. To enhance a good lookout, have wings level sections in the overhead rather than a continuous turn.

Avoid giving too much attention to ground features during these phases, maintaining a lookout for other aircraft is more important as NORDO aircraft will not be heard and must be seen.

Additionally, look for gyrocopters, helicopters or gliders that may have a closer-in circuit than you expect. Likewise, high performance aircraft such as twin-engine or warbirds may operate a wider circuit.

Descend to circuit height

When established on the non-traffic side, descend to circuit altitude. A low rate of descent is preferred because of the potentially high traffic density around an aerodrome. Common practice is to use a cruise or powered descent.

The aircraft crosses onto the traffic side over the upwind threshold at circuit altitude. That provides the longest possible downwind leg, while at the same time still providing maximum vertical separation from high-performance aircraft taking off, or an aircraft that may be conducting a go-around. This is predictable positioning for everyone’s situational awareness.

As the downwind leg will be shorter than normal, the pre-landing checks can be completed during the descent on the non-traffic side or on the crosswind leg (refer CFI).

On this crosswind leg, correct for drift, in order to track at right angles to the runway. A good lookout will need to be maintained for aircraft flying on the downwind leg. Do not turn in front of any such aircraft – always position behind.

The downwind radio call is made as soon as the aircraft is established on the downwind leg, and the circuit is completed in the normal manner.

Controlled aerodrome joining

The standard overhead join can be carried out at controlled aerodromes with a clearance from ATC. More normally you will join via one of the circuit legs, usually downwind or via base leg.

Consult AIP Vol 4 for differences, particularly where there are neighbouring aerodromes.

Airborne sequence

On the ground

Make sure the student has all the necessary information to hand, and they have briefed themselves on the landing chart.

The exercise

Vacate the circuit as cleared by ATC, or the way you discussed in the briefing.

The student will have already seen in previous lessons how to vacate the circuit, but you may need to prompt some of the radio calls.

If you will be using your home aerodrome for the standard overhead joining procedure, head away in an unfamiliar direction, to add a little realism.

Begin the exercise between 10 and 5 NM from the aerodrome, over a local feature or VFR reporting point.

Talk through the standard overhead join procedure, and then have the student practise before any solo practice.

From the downwind leg, an approach and landing or go-around can be carried out before vacating the circuit for student practice. If this is your home aerodrome, you may elect not to do the landing, instead taking the opportunity to practise a go-around. If it is an unfamiliar aerodrome, however, landing practice would be beneficial.

It is advisable for the student to experience approaches from different directions and to different vectors before conducting solo practice.

After flight

There probably won't have been time to cover every method of vacating and joining the circuit, so advise the student that you will take the opportunity in future lessons to practise these different methods.


Vacating and joining at aerodromes whiteboard layout [PDF 110 KB]


Revised 2021