Tuesday, April 19, 2011

What is a go-around?

The latest news item featuring air traffic controllers does not, for a change, have another tale of yet another controller napping on duty. Instead we have a story of the plane carrying the First Lady being told to go-around after coming too close behind an Air Force C-17 cargo plane. The First Lady's aircraft, a Boeing 737, has to be spaced at least five miles behind the C-17, which is a heavy jet. Long-time readers may recall that I discussed wake turbulence in a multi-part series last year. When the spacing between the aircraft was observed to be insufficient, the B737 was told to go around.

So what is a go-around?

A go-around is a standard procedure where the pilot of a plane on final approach to landing instead aborts the landing attempt and climbs up and away from the runway. This maneuver may be initiated by the pilot or the controller when conditions are such that a continued approach to the runway would not be safe.

This could be for a number of reasons:
  • The runway is not clear
  • Wake turbulence spacing is inadequate
  • The pilot determines that the airplane is too high or too fast
  • The aircraft has some sort of mechanical or configuration issue that prevents a safe landing (most commonly an unsafe landing gear indication or flap problem)
  • Sudden change in the weather conditions that make a landing unsafe (wind shift, wind shear, or microburst are the usual culprits)
While this list is not comprehensive, these are the most common reasons for go-arounds at LAX. While it may sound extraordinary, we see these everyday. At LAX, most are controller initiated due to the preceding aircraft not being able to exit the runway before the next arrival reaches the runway threshhold. Go-arounds are sufficiently common that we have standard procedures for how a go-around is handled. In most cases, the aircraft flies a rectangular pattern that puts it back on final approach to the runway a few minutes later, and it is subsequently able to land without any further incident. What made yesterday's occurrence newsworthy was the personage aboard the airplane.

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