Magnet?Air shipping Rules & Regulations
An aircraft “wet” compass
There are two important measurements of a package containing magnets. Rule #1: If the field strength is 2 milligauss (0.002 gauss) or more at a distance of 7 feet from the package, the IATA (International Air Transport Association) says the package needs to be labeled as Magnetic. This is especially applicable for international shipments.
Magnets are often shipped in a steel-lined box to remain below this limit.
If there is any chance that the arrangement of magnets could change, or any package shielding could be damaged so that a measurement exceeds this value, it falls under the Dangerous Goods category and should be labeled as Magnetic.
Rule #2: For any package shipped by air, whether it is labeled magnetic or not, the field strength must be 5.25 milligauss or less at a distance of 15 feet from the surface of the package (FAA Title 49, Part 173.21 Forbidden materials and packages). If the package measures above this value, don’t ship it by air.
Why are these rules so important? The magnetic compass. Despite all the fancy GPS navigation systems, the basic compass is still an important part of aircraft navigation. If a cargo of magnets alters the compass readings, accurate navigation might be compromised.
Remember, your magnets are competing with the magnetic field of the Earth, whose strength is only about 0.5 gauss on average.