Day: August 3, 2005

In the mid-1990s when I started building online communities I didn’t understand why publishers like Amazon pre-moderated all user-contributed content such as comments.  The vast majority of users were intelligent and well-meaning and only a small fraction of material had to be deleted.  It seemed like it wasn’t worth interrupting the flow of conversation and exchange to ensure that an off-topic posting never saw the light of day.  It would be intercepted within a day or so and deleted in any case.

The Manila software that Harvard runs behind these blogs shows the foolishness of my point of view.  More than 90 percent of the comments posted to this blog are link spammers trying to increase their Google rank by adding comments to old and forgotten postings.  Manila makes it impossible to delete this spams except one by one, each one requiring a several page process of confirmation.  In the old ArsDigita Community System we had a “delete all from this user” and “delete all from this IP address” option that made it a lot easier.  But in the Age of Spam what we really need is pre-moderation.  Maybe there should be an option for a vibrant interactive discussion that content goes live for 24 hours without being approved but otherwise given the small percentage of useful non-spam content it seems that the only answer is that nothing goes public without approval.

Another reason to program in pre-approval only is that eventually the moderators of every online forum find other things to do with their lives.  The server doesn’t realize this and soldiers on processing postings.  Spammers discover a happy home and the database fills up with crud.  Software should be robust to the moderator disappearing and in an Internet that is mostly spam that means approval-required-before-going-live.

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Friends have been asking me for an explanation of the Air France Airbus crash in Toronto yesterday.  It is tough to say without a full accident report.  Whatever the report concludes the accident will underscore the important point that a pilot should never commit to a landing.  There is a temptation in aviation, especially after a long flight, to conduct the approach and landing as though it is inevitable that the plane must continue to descend and stop on the runway.  Unless you’ve run out of gas or suffered some sort of catastrophic engine failure in a single-engine plane, however, there is nothing inevitable about continuing the approach and landing.  A pilot can at any time make the decision to add power and go around.

When does it make sense to go around?  The airlines have rules about stabilized approaches.  The plane should be at the right airspeed, at the right position laterally and vertically, at the right descent rate, and configured for landing when it is still about 1000′ above the runway.  If not within tolerances, the pilots are directed to go around and, at least in training, they always adhere to these rules.  A light airplane is more subject to turbulence and has less inertia and therefore is easier to adjust.  The tolerances can probably be relaxed a bit and the deck lowered to about 500′ for a single-engine four- or six-seater.

Suppose that the winds are super gusty over an entire region, as is common here in the Northeast.  Or suppose that you’ve just flown many hours and are tired.  Or suppose that there are thunderstorms and it isn’t obvious where you could go that would be totally safe to land.  The rules get bent.  In general not nearly enough go-arounds are made by either small or big airplane pilots.  Usually the decision to fix a bad approach doesn’t result in an accident.  And indeed in Toronto these guys might have been okay if only they’d been on the 11,000′ runway 23 instead of the 9000′ 24L (the runways are oriented facing magnetic direction 230 and 240, i.e., almost the same, so it is unclear why the Airbus wasn’t assigned the longer runway).  They might also have been okay if they hadn’t been in the famously underpowered A340-300 (the newer versions of this plane have almost twice as much power) and therefore requiring more runway remaining before going around.

The cause of the crash might yet prove to have nothing to do with the pilots’ decisions.  Nonetheless it is probably a good idea for all of us who fly to remember to keep a hand on the throttle and tell ourselves that this is only an approach and that we won’t commit to the landing until we’re very nearly stopped on the runway.

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