Of logs and time zones and systemd

Back in 2005 I wrote about syslog brokenness — specifically, the fact that each entry is logged in local time zone, but with no indication of what that time zone was at the moment the message was logged. Because time zones change, this means there are periods of time every year where log messages are ambiguous. If your logging device moves across time zones, the problem is even worse, and sure enough, the problem has finally affected a real life case: we don’t know what happened just before the Amtrak 188 train derailed, because the timestamps on assorted logs were ambiguous.

Iterative bad design

« Concerns have been raised about intermittent faults when opening the doors of the Class 377 trains at certain stations on the Thameslink route. » The original problem? Engineers decided to use GPS location to determine whether the trains are in a station. Unfortunately, GPS is provided by satellites, so it doesn’t work in tunnels or underground — for example, at stations like St Pancras. The engineers’ solution: Install GPS repeaters in the stations to transmit GPS signals down the tunnels.

Who needs terrorists?

New York Times via RISKS digest: A drive by the Federal Aviation Administration to cut the number of air traffic controllers nationally by 10 percent below negotiated levels, and even more sharply at places like the busy radar center here, is producing tension, anger and occasional shows of defiance among controllers. Most of the changes have had little effect on the public. But one in particular may have safety implications, controllers and some outside experts said.