Circuit patterns and collision avoidance with aircraft on departure

[xray20]

Can someone please clarify the rules about crossing runway axes when on approach or in the circuit?

After having a couple of near-misses with multiplayer and AI aircraft while crossing the line of the runway while entering the circuit, I began to wonder what the real world rules are to prevent this.

 

I checked Wikipedia and the FAA diagram (attached) doesn't help as it shows an aircraft on the crosswind leg apparently crossing the departure vector.

[Johnny Dioxin]

I have several diagrams for this from when I was in VATSIM a few years ago - think they were on the VBFC site (Virtual Bristol Flying Club) so you may want to look there - they are very good (click on "Training" and look through to the diagrams at the bottom of the page about joining circuits, too).

 

http://www.vbfc.co.nr/

 

in the meantime, by the power of Google, I found this pdf document:

 

Circuit Training

 

Of course, civvies don't use the break join etc - but it's a good start and follows international standards.

 

If you meet another aircraft going in a different direction, one of you is at the wrong altitude, but it's very rare to see, or for many to know, this information in the DCS World theatre. There are the real data sheets, but I doubt anyone sticks to them in-sim (except maybe virtual squadrons who have their own rules).

Edited November 11, 2015 by Brixmis

[Lusik]

In General Aviation it usually depends on the size of the airport. On small uncontrolled airfields it it usually good practice to overfly the airfield at least 500ft above traffic pattern height which is usually 1000 ft AGL, if not published otherwise. We do this to check landing conditions on the runway, check the windsock, etc. On slightly larger airfields or towered airfields you usually receive pattern entry instructions from ATC.

 

I fly Cessnas and similar aircraft so I can't comment now military patterns are flown. There are a few different approach methods but I'm not an expert in this area.

[canadianbaken]

FYI if you look at your Kneeboard maps they have all the data for entry and exit points for the airports. This does not mean that people in multiplayer are following these guidelines but they are there.

[-Flo-]

Basically everything has been explained pretty well here. If it is a controlled airfield, atc will tell you where to enter the circuit (eg on base, downwind)in order to keep the traffic flowing, for example:"D-EXYZ, enter left downwind, RWY 09L." When approaching an uncontrolled airfield, the pilot chooses and announces the pattern entry, unless explicitly stated otherwise in the charts: "On downwind rwy 09L, D-EXYZ." The basic rule here is "See and Avoid", as a pilot you are responsible for traffic avoidance and monitoring the pattern area.

 

IIRC, when i was in the GAF at a Control and Reporting Centre listening on the TWR freqs, most of the time our Tornados where given vectors to final.

From personal RL civilian flying experience, the only need for a traffic pattern is to manage your own approach, most of the time it was a straight in approach.

Edited November 12, 2015 by -Flo-

[Mike5560]

In DCS, you will have a bit of choas near the airfields as they are essentially uncontrolled. Typically, ATC will monitor every step of your entry and exit of the airspace. When departing, ATC will assign you instructions based on your intentions or flight plan. ATC will tell you when you are approved to switch frequencies off the ATC freq.

 

When arriving or doing pattern work, the pilot entering the airspace will contact ATC and say his position, type aircraft and intentions, at which point, ATC provides relevant data regarding winds, ATIS, altimeter, active runways and where to proceed.

 

Crossing a runway centerline will typically be part of a published pattern. If an aircraft practices a touch and go, then said aircraft will "request closed traffic" meaning he would like to re-enter the pattern and ATC may approve a right closed traffic or a left.... Which means the aircraft airborne over the runway may turn right or left crosswind to re-enter the downwind leg, then base leg, etc.

[Ventus_Clu]

Don't mean to necro this thread, but it came up in a search I did and figured I'd chime in and explain how the military do it for those who are interested or search for it in the future.

 

The following is how BritMil control their circuits for FJs, however I've controlled C-130's breaking into a visual circuit as well as light aircraft (Tutor, Tucano) as well as semi-civilian (i.e. FA20 flown by ex mil).

 

I've also controlled foreign Mil (USAF, USN, Danish, German, Turkish, Saudi, Swedish amongst others and have found that while most visual circuit patterns are similar, no-one seem's to understand how we do it)

 

I know some people know how civilian patterns work but BritMil work quite differently.

 

Circuit Positions

 

Firstly I'll talk about circuit positions. We use 4 of them, deadside, upwind, downwind and finals. Civilians and pilots from other nations, including some of the "old and bold" try to pretend that we have extra positions (i.e. crosswind, base leg, long/short finals) but we no longer use them in the RAF/RN.

 

Upwind, is any position between the runway and flying in the opposite direction to the runway.

 

Downwind is the straight section which is flown in the opposite direction to the runway.

 

Final is from when you begin your turn from downwind towards the runway until the runway threshold. Weather you touch it or not in the case of a low approach (for the "old and bold" they are no longer called overshoots no matter how many times you request them you will only ever get cleared to low approach)

 

Deadside is the airspace the side that the circuit pattern is not flown usually used when aircraft join the circuit but can also be used for various other purposes if the controller or local orders require. I.e. I have used it for RW training when I had FJs in the circuit, kept them separate and thus safe.

 

General Circuit Information

 

Circuits at RAF/RN bases are usually flown left hand (I was told it was because in the "old days" it was easier to turn left as the control stick was in the pilots right hand how true this is I don't know) If a circuit is flown right hand for whatever reason then we call the runway a right hand runway i.e. RW 23RH. this does not mean the airfield has 2 runways and you are being asked to join for the right one unlike civilian ATC.

 

A typical height will be 1000ft QFE (AGL) however local orders may differ or have different heights on occasion such as RW or light aircraft fly circuits at 500ft QFE. For safety whenever this happens you never mix and match circuit heights. The only exception to this is sometimes a FJ will ask to do a low level circuit (if local rules permit) this may be approved with others in the circuit provided the controller thinks it will be safe. personally I've never allowed it with more than 2 others of the same type in the circuit evenly spaced.

 

As a "Visual Circuit" is just that "Visual" they are rarely open if the cloudbase is low, usually 1200ft is the cutoff, or visibility is poor, in the region of 4km. However if there is any doubt as to the visual integrity of the circuit or that safe integration of joining traffic either IFR or VFR cannot be guaranteed then the circuit may still be closed.

 

Circuit Calls

 

The basic calls made in the visual circuit are a Downwind call and a finals call. The downwind call is where the pilot confirms he is now downwind, to both the controller and other pilots in the circuit, and his intentions for the runway, land, touch and go or low approach (sometimes more intentions are added such as low approach then a VFR or IFR release from the visual circuit, or a request the next one is a low visual circuit or even something else). ATC will acknowledge this by passing the surface wind.

 

The next call is the finals call where the pilot will again confirm his position in the circuit followed by a confirmation his gear is down, then providing it is safe ATC will clear his approach or tell him to continue or flat out tell him to go around.

 

If continuing a later call by ATC may clear his approach or to go around, if ATC says nothing (or breaks) then by 200ft the pilot should initiate his own go around and call it. This is where he pulls up (obviously) and turns off to the deadside. This may be because ATC had hoped an aircraft would have taken off by now so the pilot could land but instead the stupid trainee pilot took forever to do his pre-takeoff checks, rant over.

 

There are no other calls required, if the pilot is doing circuit training then after his touch and go or low approach he just turns left when its safe to do so and wont speak to me until he is downwind.

 

Joins

 

There are several different joins available depending on what ATC want however what is often referred to as a "visual join" is actually a VRIAB (Visual Run In And Break) the propose of this is that it's the fastest way to get a FJ on the ground.

 

It begins by the pilot being handed over to the tower Fq and a decent range normally +10nm, the pilot will check in on fq with his intentions. ATC will respond with a join instruction giving the pilot permission to join the runway (with circuit direction if other than left hand) and number of aircraft in.

 

The pilot then positions them self into the initials point, a point about 3-4 nm before the threshold of the runway in use offset to the deadside by 1 nm, depending on the local rules his speed could be anything below the speed of sound (although I've never seen local rules allowing them faster then 450 kias) Pilot will then call "initials" ATC will respond with either "callsign" or the position of all the circuit traffic starting at deadside then upwind, downwind, finals finishing with on the runway.

 

Pilot will then look for said traffic and say if he can't see anything, ATC will assist (remember it's a "Visual Circuit")

 

When abeam the runway pilot will then "break" into the circuit (lots of G's YaY that's why I became a fighter pilot) he may even aim for a point between an aircraft upwind and another downwind, especially if it's typhoon Vs tucano (probably something said pilot will talk about with hands later in the bar)

 

The pilot will also call "on the break [intentions]" ATC will try to respond(work out) with how many ahead and the surface wind, this is the same as a downwind call. the rest of the circuit is as discussed.

 

In addition to being the fastest way to join, it also keeps the aircraft safe by way of, if anything was finals or on a instrument approach the joining aircraft will be deadside of it and should be visual with it before entering the circuit so if aircraft on finals decides to go around then the joining aircraft can react (and curse). in the case of IFR aircraft the joining, aircraft will not be given to tower (and even re fed in) until they are visual with IFR traffic.

 

In the case of departing traffic, as the joiner should break above the runway at 1000ft there is no confliction. The aircraft taking off should have SA listening to the tower Fq so as to know not to do a performance take off (not a worry with GR4's LOL) and the Joiner should be visual and have been told about the departing aircraft so if a late break is required the pilot can say over radio so departing aircraft knows not to be stupid.

 

Other joins include straight in joins and downwind joins.

 

Downwind joins are only ever done if the circuit is empty or one is departing and is told about the joiner.

 

straight in joins are given to tower at about the 10nm point and call tower with a request for a SI join, ATC reply with SI join approved and number of circuit traffic then to report 4 miles gear down (we have to remind pilots you see)

 

at 4 miles the pilot will(should) give ATC a 4 mile call his intentions and a gear down, ATC will then give him a clearance or a continue. Hopefully the pilot has had time to see all the circuit traffic and will ask for anything he can't see (it's still a "Visual Circuit")

 

To avoid confliction with circuit traffic a priority will be set up in local orders, usually that a SI will have priority over visual circuit traffic, this means that if there is doubt that a visual circuit aircraft and a SI joiner can both get their approaches is then the visual circuit traffic will be told to go around.

 

 

I know this was a long post in an old thread but I have seen so many post both here and on other forums with misunderstandings on how visual circuits are done or not understanding them I figured I'd finally shine some detailed light on the matter. As I said this is just for BritMil airfields and civilian and other NATO countries are usually different. but maybe it'll help out those in the UK who listen to Mil bases on scanners and wonder whats happening.

 

Any questions feel free to PM

[Milli]

Thanks Ventus_Clu for the above post, good to hear real world procedures from someone who has direct experience.