The Polish Leadership Air Disaster: It Probably Wasn't the Airplane

We can hardly imagine the ramifications for Poland of the loss of so many of its political and military leaders in one disaster. All sympathies for a country and people with enough other challenges at the moment. (And, in obvious painful symbolism, to have the loss be part of a commemoration at Katyn.)

As mentioned many times before*, it takes a very long time to be sure about the "accident chain" that led to any given aviation disaster. This is an term of art for describing the whole cascading sequence of bad judgment, bad circumstances, and bad luck that eventually leads to a disaster. It is called a chain because breaking a link at any point will usually avert the tragedy.

But here is a line of initial speculation that I bet will lead nowhere and should be played down: suggesting that the airplane itself, a Russian-made Tupolev-154 that will probably be described as some aging rustbucket overdue for replacement, was the "cause" of the crash. Eg, a lead item from the BBC just now:


Maybe there will prove to have been something wrong with this airplane. But here is why that seems unlikely:

Suppose you heard about a fatal car crash that happened at 3 am during a freezing rainstorm. And on a twisty road, with poor lighting, on a Saturday night, with a teenaged driver at the wheel. Your first thought might conceivably be, "I bet the car was defective." But you would be more likely to think of a lot of other tragically-familiar risk factors that could have played a part.

Based on initial reports, this crash appears to be the aviation counterpart to that 3am freezing-rain case. I say that because:

- According to initial reports, the Smolensk field in Russia was subject to heavy fog at the time of the crash. (For details, check this Weather Underground site.)  To spell out why this matters, see below.**

- If this were an airport in the US or most of Western Europe, I could quickly look up an approach plate online and see what kind of "precision approaches" were available. The world's busiest civilian airports often have "Cat III" approaches, which can allow an airplane to land safely (by autopilot) even if the pilots never see the ground at all. I don't see any listings that show whether the Smolensk airport had instrument-landing procedures of any sort,*** but it is very hard to imagine that it offered Cat III, zero-visibility guidance.

- Initial reports suggest that the accident happened not by a very small civilian airfield south of Smolensk but near a larger military base north of town. Aerial view of the base, via Google Earth, below. Click on the image for a somewhat larger view; go here in Google Maps for the actual scene, which you can then zoom to very high resolution.


The significance of the close-up photo -- assuming this is the airfield involved -- is that the runway-ends and overall airport area do not show the signs of lighting systems and other equipment you would see even for "normal" precision approaches, for instance an ILS. These would allow an airplane to land with limited (but not zero) visibility and a ceiling a few hundred feet above the ground.

- According to some early reports, the crash occurred not on the first attempt to land but on a later one after the pilot had aborted earlier attempts and "gone around" for another try. Other reports say that the Russian air traffic controllers told the plane to divert instead to Minsk. The aviation cliche term "get-there-itis" refers to the external pressures that induce a pilot to undertake a flight -- or attempt a landing -- when he knows he shouldn't. The presence of the country's entire leadership on a plane, heading for an important commemoration, would no doubt have increased pressure on a flight crew to show their skills by getting the plane onto the ground.

So: this is a terrible, terrible tragedy. And the details, as always, will take a while to fully sort out. But as with the 3am road crash during an icestorm, there is a pattern of past tragedies this one fits. RIP. (Footnotes after the jump.)

* Links when our "categories" feature returns.

** The fundamental problem with landing in fog is that you can't see the runway as you descend. Except for the fully-automated Cat III-style landings described above, everything about landing an airplane involves the "sight picture" as you bring the airplane down, in three-dimensions, toward the runway. Under Visual Flight Rules, you're looking at the runway during the whole descent. Under Instrument Flight Rules, the variety of different approaches are really distinguished by how close the electronic guidance can take you to the ground before you see it with your own eyes for the last stages of descent and landing. If you can't see the runway, you're in the same predicament as someone driving 100mph on a twisty road in dense fog -- you're headed for destinations you can't see.

*** Over the decades, a wide variety of instrument-approach systems have evolved to get pilots in a position to land even if they have to descend through a layer of clouds or deal with other limits to visibility. But many, many airports around the world have no instrument guidance at all; in theory, you can't legally (or safely) land there if you can't see clearly all the way in. I don't at the moment see any listings of what instrument approaches, if any, applied at this airport.