Prior to the trial, aircraft departing the airport (taking off) would climb on—or with a slight deviation from—runway heading. The regular departure heading for both runways 17L and 17R is 165° but heading 155 is used for runway 17L when two runways are being used for simultaneous departures. While these departure headings are necessary to the consistent and safe management of traffic at YYC, the trial will evaluate a second set of headings that will be applied tactically when conditions permit.
In addition to using existing headings for departures, air traffic controllers will be able to assign heading 135° for departures from runway 17R and heading 185° for departures from runway 17L. These headings will be used based on the flight plan of the departing aircraft.
Historically, the distribution between a north (35 L/R) and south flow (17 L/R) has been approximately even; the new headings will only apply when departing runways 17 L/R. It is not anticipated that the trial will affect flow direction, as this is primarily determined by wind and weather conditions.
The ability to apply the Alternating Departure Headings may be further impacted by weather, capacity considerations, construction, runway surface conditions, ground infrastructure, taxiing requirements, traffic and fleet mix and operator requests.