Safety Pilot:

Let's take an excursion!

October 3, 2011

Excursions bring to mind a fun-filled family outing, but in the aviation world, excursions are something to avoid. By now, everyone knows or should know about the runway incursion problem, and the focus is now expanding to include runway excursions as well. Loosely defined, if the aircraft doesn’t leave the runway surface as planned—that’s an excursion!

The two proper ways of leaving a runway are to become airborne without hitting anything and, when exiting, to do it on pavement.

Some well-known excursions involve the airlines: The Southwest Airlines 737 at Chicago Midway that slid off the end of a snowy runway (“ Landmark Accidents: Overrun!” December 2008 AOPA Pilot); the American Airlines 737 that slid off the end in Kingston, Jamaica; the recent Caribbean Airlines 737 in Guyana; the American Airlines MD–82 in Little Rock in 1999 (“ Landmark Accidents: Bowling Alley,” June 2001 AOPA Pilot). There are plenty of additional examples.

These particular landing accidents involved some sort of runway contamination such as snow or rain. Adverse winds were also contributors. The Caribbean accident is still in preliminary status, so the details may change.

Shifting to turbine GA and takeoffs, there’s the Teterboro takeoff in a Challenger 600 that went awry, and another Challenger failing to get airborne in Montrose, Colorado (“ Rocky Mountain Low,” October 2006 AOPA Pilot). A Lear 60 blew a tire on takeoff out of Columbia, South Carolina, and a TBM 850 in Iowa stalled on takeoff. Out of balance, a contaminated wing, a blown tire, and a downwind takeoff are the probable causes in this small sample.

Light general aviation has a far-less-than-stellar record when it comes to excursions. According to the 2010 Joseph T. Nall Report, compiled by the Air Safety Institute, just more than 40 percent of the noncommercial fixed-wing mishaps occur in the takeoff or landing phase of flight. Not all of those could be considered excursions but most of them are. Longer runways are advantageous in keeping the aircraft on the pavement. Light aircraft need so much less runway that the margins are proportionately greater and yet we still manage to go off-roading.

Unlike the airlines, though, GA also operates out of many short or obstructed runways. At the small airport where I learned to fly, at least one transient would tiptoe through the tulips annually. The trees and railroad embankment did a fine job of stopping airplanes but didn’t do much for preserving them in flyable condition. There was great incentive to be on speed and on altitude.

Which brings us to something so obvious that it doesn’t seem worth mentioning, except that too many of our pilots have forgotten what I call the “Goldilocks parameters.” Too much or not enough airspeed, too much or not enough altitude, or a misalignment will lead to an excursion. They all have to be just right lest one of the bears gets upset. Doesn’t matter if you’re flying a jet or a J–3, the principles are exactly the same.

Because most pilots tend to be wary of stalls, the tendency is to add airspeed. If five knots is good, maybe 10 knots is better. An old Mooney I used to fly chewed up an impressive amount of runway when landing with an extra five knots. On speed, it was one of the nicest-landing aircraft. Less-streamlined airframes are more forgiving, but sloppy airmanship does not serve well on shorter strips.

Downwind takeoffs and landings are universally a bad deal. In several of the cases cited above, had the pilot(s) chosen a different runway more aligned with the wind, chances are good they wouldn’t be a topic of this discussion. Even a light tailwind makes a noticeable difference. In the case of a fatal accident in Owatonna, Minnesota, a Hawker 800 business jet landed with an eight-knot tailwind. The NTSB, comparing the computed landing distances between no wind and a 10-knot tailwind, estimated that it could take 843 feet, or about 20 percent more, and that was before the wet runway was factored in.

Aircraft flight manuals and pilot operating handbooks used for light aircraft may underestimate the distance needed to stop on wet runways. My belief is that the performance figures used in light-aircraft POHs are better used as marketing comparisons than as operational numbers, especially in any adverse conditions. For light aircraft, the Air Safety Institute recommends adding 50 percent to whatever the test pilots were able to eke out with a new aircraft under similar ambient conditions.

Managing the best two out of three of Goldilocks parameters still won’t keep us out of the rough. Misalignment is the leading cause of runway departures for light aircraft. That’s shorthand for departing the sides of the runway and is most often caused by lazy foot syndrome—where the pilot fails to use rudder in appropriate quantities to stay on the runway centerline.

To corrupt the title of a wonderful book by Robert Fulghum, everything you needed to know about runway excursions wasn’t learned in kindergarten but as a student pilot. Just as we forget the profound lessons of childhood, as we go about busy aeronautical lives; growing into bigger, faster, more sophisticated aircraft; so too we forget the profound lessons of basic airmanship. They don’t change.

Bruce Landsberg was named president of the AOPA Foundation in 2010.