DST and related foibles

[David Farber <dave () farber net>]

Begin forwarded message:

From: Bob Frankston <Bob2-19-0501 () bobf frankston com>
Date: March 9, 2007 11:23:42 AM EST
To: dave () farber net, ip () v2 listbox com
Subject: DST and related foibles

DST is the real test for Y2K fears -- it's a question of how  
resilient we are. At least we don't have warnings about planes  
falling out of the sky.



The problem is that the DST change is exercising systems that have  
accumulated implicit assumptions. It's useful to have such traumas as  
a way to force learning -- or else don't have them at all. At least  
we've been used to DST so we don't make the naïve assumption that  
every day is 24 hours though on the average we can still assume it's  
true.



But leap seconds are far more perverse -- we can't assume that we  
know how long a minute is nor predict future time spans. Unlike DST  
we can't deal with it so go into denial and pretend leap seconds  
don't exist.



The DST change reminds me of the years it took to recover from having  
my zip code changed -- some credit card companies got very confused.



A different kind of systemic failure occurs if your nickname has a  
different initial from your formal name as in Robert/Bob -- airlines  
use algorithms from the 1960's and R Frankston cannot be matched to B  
Frankston. Of course they still don't handle hyphens or anything  
beyond the old 6 bit codes.



Today’s Globe had a story about the unanticipated consequence of  
opening up a new runway at Logan Airport. The approach patterns for  
two runways now pass close enough to trigger collision alerts even  
though there is no real danger. I presume that the landing control  
systems will now have to have a model of the collision avoidance  
systems so as to avoid trigger them inadvertently while not putting  
in too much slack lest the landings get delayed.



These are relatively minor compared how the presumption of scarcity  
in tele-communications leads use it impose QoS regimens whose effect  
is to assure scarcity and how the presumption that everything has to  
be billable locks us into schemes that are frightfully expensive lest  
a bit go unmetered which creates expenses that …



These interactions abound --- too bad there seems so little interest  
in understanding them. The solution is looser coupling and, to a  
large extent, that’s why Y2K couldn’t have been as bad as many  
feared. But DST will provide us with lots of “morning-after”  
amusement if not worse. That’s why doing it over a weekend is so wise  
– Sunday will be learning-day.



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