All I know about airplanes I learned from Patrick Smith.

But, I am surprised by the Midway crash. It seems as if every action was "within parameters", except for that reverse thrust delay, so it seems as if one, and only one, "mistake" led to a fatal accident. My understanding was that airplane saftey standards are set so that it takes more than one mistake to lead to a fatal situation -- at least, that's how I (and the experts) am guided when making decisions about cycling in traffic.

It also seems that there were no "unusual" physical events -- you know, like a runway far slicker than expected for the weather conditions. I'd be surprised if a thorough investigation of the accident did not undercover additional sources of human error.

As for lightning strikes: I'm surprised that there is a plane to be built of composites, given the rate of lightning strikes. Again, I had always assumed that safety margins were calculated to provide astronomically small risks per flight. If composites crack during a strike, and a strike can happen once a year, this seems very problematic?

To answer a couple of reader queries:

Crews use a combination of signage, lights, and surface markings to determine distance along a runway.

Landing two thousand feet beyond the threshold is not unusual. Although crews occasionally aim slightly short, or slightly long, as the situation may warrant, aiming for the *very end* of a runway would be dangerous. Instrument landing systems, like the one used by flight 1248, typically guide aircraft to a point about 1,500 from the threshold. Legally, the designated "touchdown zone" is the first 3,000 feet or half the strip's total length, whichever is less.

However, with respect to unusually short runways, some carriers *do* require that go-arounds be initiated if the aircraft is not down within a specific distance -- usually between 1,500 -- 2,000 feet. I am unaware of Southwest's policy.

Patrick Smith