Re: Did a 16-bit counter overflow shut down Comair?

From: Avleen Vig (lists-bugtraq_at_silverwraith.com)
Date: 12/29/04

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    Date: Wed, 29 Dec 2004 00:41:12 -0800
To: "Richard M. Smith" <rms@computerbytesman.com>

    This isn't at all surprising.
    There are numerous industries which run "old" software like this. There
    are several reasons not to upgrade:
      1) The software is currently "good enough"
      2) It would cost too much to upgrade
      3) The original designers are long long gone and no-one knows
                     everything about the application any more (although this is also a
         reason TO upgrade).

    There are several money-lending organizations which run "old" software
    like this too quite happily.

    On Tue, Dec 28, 2004 at 12:44:20PM -0500, Richard M. Smith wrote:
    > Hi,
    >
    > On Christmas Day last Saturday, Comair Airlines had to completely stop
    > flying
    > all of its planes due to computer problems. Comair blamed the computer
    > problems on their pilot scheduling software being overloaded after bad
    > weather earlier in the week forced many flights to be rescheduled. Comair
    > now hopes to have all of its 1,100 daily flights restored by tomorrow.
    >
    > An article which was published today at the Cincinnati Post Web site
    > provides some interesting details of a software failure in Comair's pilot
    > scheduling software:
    >
    > How it happened
    > http://www.cincypost.com/2004/12/28/comp12-28-2004.html
    >
    > According to the article, Comair is running a 15-year old scheduling
    > software package from SBS International (www.sbsint.com). The software has
    > a hard limit of 32,000 schedule changes per month. With all of the bad
    > weather last week, Comair apparently hit this limit and then was unable to
    > assign pilots to planes.
    >
    > It sounds like 16-bit integers are being used in the SBS International
    > scheduling software to identify transactions. Given that the software is 15
    > years old, this design decision perhaps was made to save on memory usage.
    > In retrospect, 16-bit integers were probably not a good choice.
    >
    > An anonymous message posted to Slashdot the day after Christmas first
    > described the software failure at Comair:
    >
    > http://slashdot.org/comments.pl?sid=134005&cid=11185556
    >
    > Earlier this year, an overflow of a 32-bit counter in Windows shut down air
    > traffic control over southern California for 3 hours:
    >
    > Microsoft server crash nearly causes 800-plane pile-up
    > http://www.techworld.com/opsys/news/index.cfm?NewsID=2275
    >
    > This problem occurred because of a known design flaw in older versions of
    > Windows:
    >
    > http://tinyurl.com/5n9gc
    >
    > Richard M. Smith
    > http://www.ComputerBytesMan.com
    >
    > 

    -- 
Avleen Vig
Systems Administrator
Personal: www.silverwraith.com
EFnet:    irc.mindspring.com (Earthlink user access only)
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