The overhead arrival

Submitted by on Tue, 01.01.2013 - 00:00
The overhead arrival

Straight in to downwind or overhead? Hmmm...

Yesterday, a pilot mentioned this situation after arriving at Rockcliffe: he was coming in to land from the South (upwind). He announced his position when released by Ottawa Tower and then again 2.4 NM away (GPS...), with his intentions to join overhead for mid-downwind for runway 27. Then he heard another pilot announcing his position as over the Gatineau River with intentions to join straight in downwind for 27. OK quickly now: has this ever happened to you?

This happens quite often at Rockcliffe and other uncontrolled airports. There are two different ways to join the circuit, overhead and straight in to downwind. Pilots will choose to use the two different ways, sometimes simultaneously. This can easily lead to dangerous conflict situations or at minimum an uncomfortable moment for pilots wondering where the others are. This situation can be complicated by additional traffic already in the circuit.

 

So how should we join the circuit?

Regulations say (AIM RAC 4.5.2 (a)(ii)):

"Unless otherwise specified or required by the applicable distance from cloud criteria, aircraft should approach the traffic circuit from the upwind side. Alternatively, 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"

Isn't that simple and clear? From now on, our preferred method of entry for the circuit will be overhead from the inactive (upwind) side. We will only use the straight-in downwind if we have ascertained "without any doubt" that there will be no conflict... In the case above, was there potential conflict? Yes. Had the pilot entering straight into the downwind "ascertained without a doubt"... Obviously, no.

OK so we know what the regulations say, but beyond that, is there a good reason for doing it that way? Let's look at what we can see in both cases.

If there is an airplane at A, and you are a few miles behind it (at B), what do you see?

  • The near end of the runway
  • The aircraft at A from behind
  • Traffic taking off from the runway and turning crosswind.

What can’t you see?

  • Traffic about to takeoff
  • Runway conditions and vehicles on the runway

Now if you are on the upwind side of the runway, at C, what do you see:

  • Vehicles and traffic on the runway
  • Runway conditions
  • Any traffic on the downwind, base and final
  • Traffic taking off and on cross-wind.

What can’t you see? Traffic at B unless it is close enough. [particularly when flying a normal left-hand circuit since B is out of C's right-hand window, possibly obstructed by a passenger.]

Traffic which you see sideways on the downwind as in the second situation is much easier to spot than traffic ahead of you: it is presenting a larger surface; it is moving across your field of view from side to side, against the background. Traffic in front of you (A and B) is harder to see as it is presenting a smaller surface, is maintaining the same distance and is not moving much against the background.

Doesn’t it seem worthwhile to take the extra time to go to the upwind side and enter the circuit there?

What about traffic already in the circuit? Who has priority?

Traffic already in the circuit (for instance doing circuits) has fewer options to avoid other traffic, so if you are entering the circuit you should arrange your timing to merge into the pattern of other aircraft safely.

If I am arriving from the downwind side of the aerodrome, how should I enter?

  1. Cross over the field at 500 feet above the circuit
  2. Once on the upwind side, turn approximately 45 degrees in the same direction as the downwind to start a “tear drop” turn, and start your descent down to circuit altitude
  3. Ensure you are at circuit altitude well before crossing back overhead. Remember there may be someone else coming behind you and crossing the field 500 feet above you.
  4. Join mid-downwind.

Following this pattern allows you to scan the beginning of downwind sooner and compensate for any wind to arrange to cross over mid-field.

The airspace around the Ottawa Rockcliffe Airport is complex and the approach methods require careful attention by the pilot.

This article was produced as a result of a real-life situation. You probably encounter situations similar to these in the course of your flying. We would like to hear about them to allow us to think about how situations like these can be handled safely and learn from your experiences.

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