Posted by: harrisonjones | April 23, 2011

First Lady…you’re number two.

Another disaster somehow avoided. My newspaper tells me that the First Lady narrowly escaped tragedy when air traffic controllers vectored her flight to within 2.9 miles of a heavy jet on approach. Say what… 

Don’t get me wrong, this was an obvious mistake and one that will be hard to explain. Life threatening? Hardly. Let’s see if we can set the scene. Heavy jets (max gross landing weight 250,000 pounds or more) create wake turbulence that require following non-heavy jets to maintain five miles in trail. A good rule that should have been enforced in this situation. However, wake turbulence descends shortly after being created at each wingtip and as long as the following flight stays above the heavy’s flight path, he will not encounter a problem.  

I promise you, similar situations occur every day at busy airports worldwide and seasoned pilots and controllers know how to play the game. It goes like this. 

“Flight 1 heavy, you’re cleared to land.”

“Flight 2, you’re following a heavy jet at twelve o’clock and five miles.”

Now the game begins. If Flight 2 says he has the traffic in sight, the controller will clear him for a visual approach and the pilot will become responsible for his own separation. Probably not going to happen. The captain sees the heavy, but responds, “We’re looking.”  

The TCAS (traffic collision and avoidance system) now says four miles but nobody mentions it.  

“Flight 2, reduce to minimum approach speed.” Flight 2 complies and also goes a half dot high on the glide slope to stay above the heavy’s path.

“Flight 1 heavy, expedite if possible, you have traffic in trail.”

If Flight 1 is truly heavy, he is not going to speed up. He needs the entire runway to get stopped as it is.

“Flight 2, S turns to the right are approved for spacing.”

The game continues until the controller or the captain decides to start over. Bear in mind that as long as the trailing airplane stays above the glide slope, there is no danger. 

Another point to remember is that the captain can initiate a go around anytime he chooses. The missed approach airspace is always protected and available to him. He doesn’t need to ask. Playing the game is fine, but no captain is going to take a chance just to make the system work. I’m sure the First Lady’s flight crew was controlling a safe speed and doing smooth S turns while remaining above the glide slope. If this is a news story, it could be published every day at every major airport in the world. Let’s do a 360 and get out of here.      

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Responses

  1. Love this perspective Harrison. I remember my first solo long cross country to Duluth Minnesota. As I was approaching the airport they gave me my instructions. Cessna 4872B you are #2 to land behind the heavy. Do you have the traffic in sight?

    I responded in the affirmative and immediately all my training regarding wake turbulance was swirling around in my brain. I did allow probably more separation than what I prbably needed for landing but I had visions of my little ole 152 flipping over in the wake turbulence.

    There are always options in regard to flying safely. Jeanne

  2. You are so right about maintaining options and having a contingency plan, or two, or three. It doesn’t matter how many hours you have or what kind of airplane you’re flying. Happy Easter, Jeanne.


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