Modern jet planes are so safe that many things have to go wrong to bring them to grief. What some of the factors might have been in this latest case.
J. Mac McClellan is known through the flying world as the long-time editor of Flying magazine. Now he has a regular column for the EAA, the Experimental Aircraft Association. He sent a message about this weekend's fatal crash at Aspen, when a private jet landed with strong and gusty tailwinds (as mentioned here).
This is more highly detailed than some readers may care to know or even be able to follow. But my experience is that after aviation mishaps of any kind, even people not usually interested in aviation are grateful for additional, detailed information.
Part of the reason may be a search for reassurance that the airplane didn't just fall out of the sky, which virtually never happens but is a widespread if unspoken fear. Part of the reason may be the complex chain of bad luck, circumstance, and (often) miscalculation that leads to a crash -- today's airliners and private-jet planes generally being so reliable and redundantly fail-safe-equipped that it usually takes many things going wrong at once to bring one to grief. Part of the reason is the unavoidable Bridge of San Luis Rey-style human fascination with the chronicles of misfortune.
In any case, here is the report from Mac McClellan.
As you know from landing there, the approach to Aspen is visually confusing because the runway slopes uphill. [JF note: In the photo at the top of the page, mountains are just out of view to the left, so planes approach from the right. The runway slopes up more than 150 feet from the right-hand side to the left.] Also, there is a depression on the ground short of the landing threshold which accentuates the perception of upslope of the runway.
The Challenger series is one of only two jets I have ever flown that is nose-down during final approach instead of level to nose up as other jets are on final. This looks really odd from the cockpit in the 601 Challenger business jet like the one that crashed, but is really strange in the longer CRJ series. That’s why many regional airline pilots call those things “lawn darts.”
The other bizjet that approaches nose down is the Hawker 4000, first called the Hawker Horizon. Originally the design called for leading edge slats which were abandoned to save weight and money. Because the slats were not included in the actual airplane the behavior of the wing is different so it flies nose down on approach. At least that’s what the experimental test pilot guys at Beech believe explains the unusual attitude.
The first time I flew the Hawker 4000 after it received some sort of provisional certification we decided to go to Aspen so they could show off its hot and high performance. I’m on final to a runway sloping uphill in a jet flying nose down to make my very first landing in the airplane and it was very strange. When the test pilot in the right seat started to gasp I hauled back hard on the wheel and got the nose up in time, but barely.
Throw in a tailwind, wind shear, the visual illusion of the runway slope, and a nose down attitude on very short final and that Challenger crew had its hands full. That is not an excuse, but my Hawker arrival at Aspen came to mind when I first heard about the accident....
I don’t want to speculate on what caused this particular accident, but the conditions of the runway slope, terrain, wind, unique approach angle of the Challenger and so on are simply noting the many challenges this crew faced in trying to land. Lots of factors all came together here that made the approach unusually difficult and that’s what we know and can say for now.
And, from another reader with experience in this field:
Like most pilots, I was tracking the reports out of Aspen closely.
One aspect that hasn't been mentioned yet is the maximum tailwind component permitted in jets. In the CL[Challenger]300 and 900XP I've flown, it's 10 knots. I'm not sure about the CL600 family but I suspect it is very similar.... [JF note: As mentioned previously, tailwinds at the time were in the 16-26 knot range.]
This doesn't answer why the crash occurred. This appears to be a loss of directional control as opposed to running off the end of the runway. I would bet you lunch (at Hardee's) the tailwind will be a contributing factor...