Denys writes:

>I have been travelling with a laptop since 1990...
>I have never had a laptop disk drive
>go bad on me, and I always put my laptop through the X-ray machine.

Will those suggesting that a low-dose X-ray machine can damage magnetic
storage please suggest a mechanism by which it occurs? I can't think of
any, save for exposure to magnetic fields from the conveyer motor or
X-ray power supply. But hard disc drives especially are shielded from
external magnetic fields. "I sent my laptop through an X-ray machine and
had data loss" is not a useful scientific experiment, since presumably
other things also happened to the laptop between uses. (If you had to
turn it on to get past the checkpoint, and failed to shut it down
properly, that also can cause data loss.)

It should come as no surprise that airport X-ray machines fog film; most
airports have signage to this effect and warn that high-speed or
medical/scientific film should be hand-inspected.

>I hate having the security personnel hand check my laptop case, or do
>power-up tests.  I pack my case very carefully, and it is set for travel,
>not messing around with.  Now in Houston after it goes through the X-ray
>machine, the bag is further tested with a sniffer to detect trace elements
>that may indicate bomb material.  I have had that procedure done to my bag
>in several European countries also...

Once again, I agree.

The policy apparently differs at various airports. Phoenix does not
require activating the machine; they now use a nitrogen "sniffer." LAX
terminal 1 always requires that I turn on the machine; like Denys, I find
this extremely inconvenient. Burbank sometimes requires that I turn on
the machine and sometimes not. Ontario never seems to, nor does San Jose
or Oakland (but my sample size at these last two is much smaller than for
LA-area airports). If you know you're going to have to switch on the
machine, you can prepare for it. In the case of my aging PowerBook, a
full power-on self-test requires about 15 seconds before the screen
lights up, and the startup chime only scares them :-).

-- Bruce


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