"I'm going to be working with a composer on the 'other' coast and we will be shipping multitrack digital tapes back and forth. The project is time sensitive so I need to make sure things arrive in tact. Are there any special precautions I should take? Does UPS or FED-EX subject material to any fields that would corrupt data?"

Historically the major carriers you mention would not scan packages with anything powerful enough to wreck the data on your tape. It may get some X-Rays, but those don't erase tapes. Unfortunately, these days, things could change at any time, and there are devices available for package scanning that can ruin data. Most of them, however, are generally only dangerous to film rather than magnetic media. I suspect they would always try to minimize the use of such devices, as they know people do ship sensitive information around in the form of hard drives and tapes.

What you DO need to watch out for, however, is your packaging. First, assume that something heavy is going to fall on your package. Do you have it packed in such a way that such a shock will not crack open the case of your tapes? A great way to package them is to put a box within a box. Use shredded or wadded up newspaper as packing around your tape. Make sure it's in the case it was in when you bought it. Then seal that in a plastic bag so the newspaper shredding doesn't contaminate it. Make sure the tape is in the center of the box, with at least three inches of packing on all sides. Many people put things directly into boxes and then stuff packing in on the other five sides. That leaves the sixth side - the bottom - exposed to damage. Once that first box is all sealed up, get another larger box and do the same process again. Put your first box into the larger box leaving two more inches on the sides. Finally seal that outer box very well with good packing tape (not duct tape). This double box packing technique accomplishes two major things.

1. Not only are your tapes well insulated from the crushing blows of things that may fall on your package, but they are also well away from the grappling hooks some of the shippers use to cut lose packages that get jammed on the conveyor belts. Your outer box may get virtually destroyed, but the inner box and its contents will be safe.

2. One of the most insidious ways to lose data in shipping is from your package being placed next to another package with a powerful magnet in it (such as a loudspeaker box). By creating a few inches on all sides of your tape you drastically reduce the already low chances of some stray magnetic field getting to them and ruining your data.