When aircraft are with Tower in the traffic pattern and have been told to “Extend upwind/downwind, I’ll call your crosswind/base” a pattern entry permits a turn to the next leg of the pattern if it’s being used for a runway change. Controllers do not need to issue the pattern entry and “turn crosswind/base” command. Here’s an example.
Two aircraft are upwind, one for 22L and the other for 22R. The traffic upwind for 22R has requested a runway change to 22L. To allow the traffic on 22L to begin their crosswind turn and get out of the way you’ve instructed the traffic for 22R to “extend upwind, I’ll call your crosswind”. Once safe to do so an appropriate command would be, “Enter left downwind runway 22L, number 2, traffic to follow is on left downwind”. This permits the traffic to begin their crosswind turn.
- Instruct the second aircraft to “enter right downwind RWY22L, number 2, traffic to follow is on left downwind”
- If you are concerned about a conflict on the other end, then you can also tell the second aircraft that you will “call their base” to alleviate this
- When you clear the second aircraft, you can then give them left traffic if you wish to do so to move them onto that side for subsequent patterns
- Instruct Aircraft 1 to “turn crosswind”
- When you are happy with the separation, simply tell Aircraft 2 to “enter left downwind for RWY22L, number 2, traffic to follow is on left downwind”
- If during this time, the second aircraft starts its right turn for RWY22R, then you can adopt technique 1 as above, instead
- Instruct the second aircraft to “extend upwind, you’ll call their crosswind”
- Wait until separation between both aircraft is adequate (you can expedite this by telling the first aircraft to “turn crosswind”), and then tell the second aircraft to “enter left downwind for RWY22L, number 2, traffic to follow is on left downwind”
- The new pattern entry supersedes the previous instruction
Whilst all these techniques are okay to use, technique one offers the greatest flexibility. Using both left and right downwind is okay to do. You do not need to have all aircraft on RWY22L in the left pattern, and all aircraft on RWY22R in the right pattern. You avoid a conflict for one pattern, then you can clear them for the option with a traffic direction so that they enter whichever downwind you’d want them on the next pattern.
It’s not one size fits all though, there may be scenarios where techniques two and three are more appropriate. The key is to be flexible and utilize the technique that is best suited to the situation.
*References: Examples from Infinite Flight Technical Writer, Regan**