1) Colorado. This afternoon a private jet crashed, with at least one fatality, at the Aspen airport. Here is one of several online reports from people at the airport or in other planes:
What is knowable, in the short run, about this sad event is that apparently there were strong and gusty tail winds in Aspen while the plane was trying to land. One of many factors that make the Aspen airport, like many other mountain airports, very demanding is that for all practical purposes you can only land in one direction. There are mountains close to the southeastern side of the airport, so virtually all flights land from the north, in the direction shown by the red arrow. (The arrow is something I've photo-shopped onto a FAA Sectional chart.)
In aviation terms, any given runway has two different names, depending on which direction the planes are going. In Aspen, planes virtually always take off using "Runway 33" -- starting at the southeastern end and going toward the northwest, over the valley, in the direction of compass heading 330 degrees. And they virtually always land on "Runway 15," coming in from the northwest over the valley, in the direction of the red arrow, and landing toward the southeast with heading 150 degrees. (I have flown a propeller plane into and out of Aspen several times. But it is so demanding and weather-dependent, and I am so aware of not being experienced enough in mountain flying, that I choose not to do it any more.)
The problem with today's weather is that the wind was blowing strongly from the northwest, in exactly the same direction as the final landing path. When you land into the wind, as pilots always prefer to do, your ground speed relative to the runway is your airspeed minus the windspeed. Thus a plane with approach speed of, say, 100 knots, and a 20 knot headwind, would touch down at 80 knots relative to the runway.
In this case, the plane had a 15 to 20 knot tailwind, which meant that its speed when meeting the runway would be airspeed plus windspeed -- 120 knots, rather than 80, in the hypothetical example. The problem with going so fast is that you can use up all the runway in a big hurry. You can't compare professional jet operations with amateur piston-plane flying, but just as a benchmark: the greatest tailwind I've ever had to land with was 5 knots, and I was impressed at how quickly the runway went by. Again, at non-mountain airports, you almost always have the choice of landing in the direction that gives you a head-rather-than-tail wind.
An archived version of today's Air Traffic Control broadcasts from the Aspen tower is available here. The accident plane's call sign is 115WF, said "one one five whiskey foxtrot." On my first-pass listening, it appears that this happened:
- The plane "went around" -- that is, aborted its first attempted landing -- because the tailwind was more than 30 knots.
- The pilot set up for another approach, and was informed that the tailwinds over the preceding minute had averaged 16 knots gusting to 25.
- The last transmission with this plane is at time 20:25, when it is cleared for landing and told of the tail winds.
- The last ten minutes or so of this archive show the tower and ground controllers deploying all the other aircraft waiting to take off and land on what has become a closed runway, after the crash.
First reports about crashes are often misleading. We know that it was a very high tailwind; what else might have been involved, we'll learn. For now, condolences to all affected. UPDATE Please see this informative item from Minnesota Public Radio, emphasizing the problem of strong, gusty tail winds.
2) West Virginia. A happier outcome from a difficult situation: A Cirrus SR-22, the same kind of airplane my wife and I have been flying around the country, had engine trouble yesterday afternoon near Buckhannon, West Virginia. The pilot pulled the handle to deploy the "ballistic parachute" that is a feature of Cirrus airplanes. It came safely to the ground, on top of a truck, and the occupants walked away. Details here; West Virginia news shot below.
3) Florida. For completeness, here is an animation, from the Air Safety Institute of the Aircraft Owners and Pilots Association, of a Cirrus crash in Melbourne, Florida, that had a more tragic ending.
Safe travels to all.
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