15 March 2008

Uncontrolled Airport arrival - Joining the circuit...

circuit joining aim Quoted here is the kind of sloppy work in the TC AIM that really bugs me, in the section on traffic circuit procedures uncontrolled aerodromes it says, "...once the pilot has ascertained without any doubt that there will be no conflict with other traffic entering the circuit or traffic established within the circuit, the pilot may also join the circuit on the downwind leg (Figure 4.6)."  My problem is that the statement quoted above and and as repeated in figure 4.6 are misleading at best and conflict with the CARs at its worst. Also, transport's authors use the word "conflict" which is not defined, but I take it to mean likely risk of collision with known traffic.

First, the statement and figure seem to suggest that in spite of any conflicts, one can enter the circuit with impunity from the upwind side as shown in figure 4.6  above? Not! The CARs clearly require one to ensure that one will not risk a collisions with other traffic (CAR 602.96) no matter how one chooses to join the circuit. Also, I doubt that the rules right-of-way (CAR 602.19) are made void by CAR 602.96.

In my view pilots doing circuits should give way to traffic joining straight in to the downwind by extending their climb straight out a little farther from the airport for separation. If there is traffic on downwind and they turn crosswind they risk collision with that traffic (thereby contravening CAR 602.19). I believe it is better to climb straight out farther from the airport for separation than it is to ultimately extend the downwind leg far past the airport because of traffic ahead. Check the midair at Mascouche in 1997 where the downwind legs stretched outside the airport's five mile zone. If someone is 5 miles from the airport they are on a cross country not the downwind leg!


If on the other hand the airport has a right hand circuit, then traffic established on downwind will have any traffic arriving from the upwind side on their right. If they collide who had the right of way? You got it the guy joining from over head is on the right of the pilot on downwind and has the right of way.

I see nothing in the CARs that say traffic established in the circuit can ignore the rules right-of-way. What the CARs say to me is that arriving traffic must avoid collisions and conform to the pattern of other traffic. They do not say don't give way to aircraft on your right when in the circuit. Also keep in mind that the CARs require all pilots to avoiding having collisions (CAR 602.19) in spite of who has the right of way.

Here is a summary of what the CARs (CAR 602.96) say about operating an aircraft on, or in the vicinity of an aerodrome (controlled or not). These are my words not the CARs.

  • Before landing or taking off the pilot must be satisfied that there will be no risk of collision with other aircraft or vehicles. And that the aerodrome is suitable for his intended operation.
  • The pilot must observe the traffic circuit so as to avoid a collision.
  • The pilot must conform to or avoid the circuit made by other aircraft operating at the airport.
  • The pilot must make all turns to the left when in the circuit, unless a right hand circuit is specified in the Canada Flight Supplement (CFS).
  • The pilot should, if able, land or take off into the wind.
  • The pilot must maintain a listening watch for air traffic control communications or if unable watch for visual signals. (As I read them the CARs do not require radio equipped aircraft to monitor the ATF.)
  • If at a controlled aerodrome the pilot must have a clearance to land, take off or taxi.
  • If not intending to land the pilot must be at least 2000 feet above the aerodrome elevation when over flying it.

No where do the CARs say one must join the circuit from the upwind side or on the downwind leg or from anywhere in particular. Nor do the CARs relieve pilots of their right of way obligations under CARs 602.19.

Let me state it quite simply, Transport Canada's statements in the AIM  about avoiding conflicts when joining the circuit on the downwind leg, appear to apply to all situations when joining the circuit, not just joining on the downwind leg as depicted in figure 4.6.

Good airmanship suggests we follow the circuit joining procedures that TC lays out in the AIM, but they should fix the wording to reflect the CARs more closely.  We are better off if we all follow known procedure--it is better to know what the other guy is likely to do and vice versa.

Michael Shaw


10 March 2008

Conflicting traffic please advise...and other useless phrases!

  "Rockcliffe Traffic Cessna 172 Bravo Romeo India five east over Orleans at one thousand five hundred in bound landing Rockcliffe. Conflicting traffic please advise..."

"Conflicting traffic please advise...", give me a break! What does this add to the system except wasted verbiage and frequency congestion. Why broadcast of your position and intentions on Rockcliffe's frequency if not to advise other pilots in the area that you are there and what you are planning to do? The whole point of making the broadcast is to coordinate your arrival with other traffic in the area. Only an idiot would not respond to your broadcast, especially if he thought there might be a conflict. I don't just want conflicting traffic to advise me. I want all traffic in the area to report their position and intentions. If I shut up and listen I will likely hear them all calling out their positions without my "please advise" request.

My normal routine is to build a mental picture of reported traffic in the area so I can decide if I will continue with my original plan or change it to ensure a smooth, safe flow of traffic. I need all traffic to broadcast their locations and intentions, not just those who think they might be in conflict.

Mr. "Please Advise" is almost as annoying as the sunny Sunday afternoon pilot who requests  an airport advisory on the ATF when there are three reported in the circuit and several others calling in bound, all broadcasting position reports. What, prey tell, is one going to find out that is not already obvious by shutting up a listening on the ATF? Nothing! Spare us the request for advisories when it is busy.

And then there is the, "Rockcliffe Traffic BRI is clear of the active..." If I am in the circuit I can see that you are clear of the active runway. On the ground, if you can't see the way is clear don't take off...We really don't need to waste frequency time with useless stuff.

For that matter, why say "Cessna 172 Bravo Romeo India." Shorten it to "172 Romeo India" or better "romeo india turning final 27 Rockcliffe, number two." I know TC expects a longer call sign but this is faster and is just as clear, as long as there is not another romeo india on the ATF.

Michael Shaw