Calm Days Provide their Own Brand of Excitement

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By Bryan Smith, Director of Cirrus Operations

As pilots we love super calm days, especially in the pattern.  We can judge our inputs and be highly critical of our skills on each takeoff and landing. We can get to know our airplanes as an extension of our body and not just a machine. Try adding this to your next calm wind day with your instructor. Fine tune your short field landings. Add 5 knots on final to see changes to landing distance and float. Try an ILS without the autopilot and set the perfect power and trim to fly it spot on with marginal rudder forces. Feel the effects of P Factor on climb out at various angles of attack. We absolutely love no wind days; however I may be pickier on my choice of airport the next calm day.

We have talked about wake turbulence and wing tip vortices, how to recognize the situation and how to avoid it for almost two decades. I have experienced it, just a few brief times in nearly 18 years. On a calm day, doing steep turns you can experience your own wing tip vortices as a speed bump style singular bounce.

I feel very comfortable flying a jet into Atlanta Hartsfield and Orlando International, so when asked to fly a Cirrus there, I didn’t hesitate. The weather at KATL was visual. Not a cloud east of the Mississippi with calm wind and warm weather in the middle of winter. Calm would become the vital word.

I was number 11 for the right side, joining behind a CRJ 50-seat commuter. Behind me was a 737.  Approach Control asked if I could maintain 140kts or better, which I could. I was warned of wake turbulence from the CRJ that was about 4.5 miles ahead. I was keenly aware that as I got closer to the airport I would need to bracket in towards the runway, bringing me closer to the vortices. That’s when tower took the handoff.

Tower warned of wake turbulence and I acknowledged that I was adjusting for the preceding aircraft. Tower quickly came back and advised of additional wake turbulence from the runway some 2000 feet to my left. That day, the left side visual approach was all heavy aircraft; 767, 777, A340, 767, 757.

I thought, well ok, and then it hit me, literally. Not so much a hit, but a super, slow motion roll to the left. So slow that I did not realize until I had almost full right deflection needed to counter. I leveled off my pitch, and the wings rolled uneventfully to level. This happened two more times on the approach. I advised Atlanta Tower and did what I thought was needed to get out of the vortices from the aircraft in front of me. Then it dawned on me why Tower warned of the other runway. This slow roll was from the aircraft on the other runway’s approach. By the time they reached me, the vortices had dramatically slowed in their roll rate, but still had plenty of energy to affect me. Once the buildings in the middle of the airport changed the trajectory of the wing tips, the rest was uneventful. This was very different from the snappier roll behind the heavy, dirty and slow 757 5 miles ahead of me going into Orlando, also on a calm day.

Two very different experiences of wake turbulence. The Atlanta approach and tower seemed to be overly concerned about my well being from vortices from an adjacent runway, while Orlando asked me to keep up my speed until short final and made one wake turbulence call out on short final for a departure 737 aircraft after the 757 landed. Both airports had calm winds with similar size aircraft on parallel runway visual approaches. I have learned that calm wind days can be full of excitement!

 

 

 

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