I bought a magnetic levitation toy the other day that involves spinning a gyroscopic top on a magnetic base to get it floating in mid air. The base contains a rather strong magnet. In a couple of days I’m going to take a long-distance ride on a train, and I’d like to carry the toy in my luggage. There are no airport-style metal detector checks on the stations for boarding or any regulations that would prohibit me from carrying something like this on a train, but I wonder if there is anything I should be aware of that could be damaged being in the same piece of luggage as the magnet. Obviously magnetic-stripe cards should not be brought close to the magnet, but what about smart cards with an RFID chip - would these suffer? What about a laptop computer with an SSD hard drive, or an RSA security token that I need for remote log-in to my company IT system - could that be damaged?
You are supposed to let the airlines know that you have a magnet in your checked baggage. Probably a hold-over from the “golden age” of flight, when compasses were still used, but the regulation is still on the books.
Does the toy’s magnet have a shorting bar installed?
Not enough coffee yet?
Careful at the hotel.
Are compasses not used anymore? Is it all GPS?
If you have a mechanical movement watch, it can easily be magnetized if in proximity to a strong magnet. Hopefully you don’t pack watches in the same luggage.
This would also apply to wearing your watch on your arm while near the magnet.
Yes, magnetic compasses are still used in airliners. But the magnetic sensors are out near the wingtips, far enough from any influencers in the cabin.
Ref @Beowulff I don’t think there are any “regulations” requiring any notice to airlines about magnets. TSA explicitly doesn’t object to magnets and neither does my employer’s hazmat rules for checked or carry-on luggage.
For true cargo there are certain restrictions that are mostly about truly massive amounts of magnetism, like a pallet with 2000# of magnets on it.
The OP of course is talking about railroad trains in Europe. Whatever he does isn’t going to harm the train. Or the train’s navigation system. 
They haven’t thought through the potential consequences of this. If the wings fall off, you could get lost.
Brian Regan is great, isn’t he?
There’s this:
https://www.intemag.com/magnet-tips-for-shipping-by-air
Sticking the magnet to a rail could cause a derailment. That could be characterized as harming the train’s navigation system.
@dlitique: I had the more colorful image of a magnet in his carry-on so powerful that as the train sped along the rails, the magnet was pulling up the receding roadbed behind the train in a curlique like ginourmous metal lathe shavings.
The haulage Co I used to work for had a contract with a local firm who made the machines that pull metal off a recycling conveyor.
We stacked the boxes two High and it was important to be sure that they were correctly orientated or the top box could ‘float’. They were liberally plastered with notices about the strong magnets.
He is very clever.
You should be quite close to where you were when the wings fell off.
Great cite. Recognizing this whole discussion about air transport is a hijack to the OP.
I’m not ignoring your cite. As I had said, there are regs about cargo transport.
I’ve been trying to reconcile the various policies and regs I know about for passenger-carried magnets with what you found vs how field strength drops off at the inverse square of the distance. So far coming up with a sensible documented definitive answer has eluded me. But here’s some data
Here’s a cite that says much the same thing but with more details on the letter of the law: Home - MCE
The operative tidbit there is in the “or” between paragraphs (c )(1) and (c )(2). Bottom line being that if the aircraft compass system is robust enough against interference, it doesn’t matter how strong the fields are.
It smells to me like as a practical matter, most consumer highly magnetic materials, e.g. hard disk drive motors, are already extensively shielded lest they fry the data on their own platters, nearby credit cards, CRTs, etc.
And so FAA, the carriers, etc., simply bowed to the reality that they’re not going to keep e.g. hard drives, out of luggage and may as well not even try. Magnetic fields in different orientations cancel at distance. So two laptops randomly packed into two suitcases that happen to be adjacent in a cargo hold are for more likely to cancel their fields than to reinforce them.
Conversely, in cargo that had been mistakenly packed without reference to the DGRs, it might well be easy for the shippers to align all the packages which would be real bad. As noted in my cite, alternating polarities to reduce the net field outside the box is an approved packaging technique.
By the airplane having a compass sensor in each wingtip, I suspect the result is the net effect of any net magnetic flux originating from the cabin is almost entirely cancelled out.
All in all it’s clear as mud to us semi-laymen.
Pack the toy as close to the three-dimensional center of the suitcase as you can manage, and the inverse square law should keep the magnetic field safe and sane.
Realistically, unless the magnet needs to be fed liquid helium, there’s probably nothing to worry about other than pinching your fingers between it and some random iron or steel object.
Fatal attraction to Iron Maiden’s.
Speak softly and carry a strong magnet.
Listening to unmemorable music from a generic heavy metal band is not usually a cause of death. The phrase “bored to death” is just hyperbole.