Taking Minibots on Airplanes

[Dale]

Since we'll be flying to our first regional and have a minibot with some VERY strong magnets on board I started researching what it takes to take one on an airplane. I haven't found the definitive FAA regulation but here's what a magnet supplier says:

Transportation
Transportation of magnetic materials by air in the United States is regulated by the U.S. Department of Transportation and is covered under the Code of Federal Regulations (CFR) 49 parts 100-185. A magnetized material is considered a hazardous material and is regulated as a hazard class 9 material when it is offered for transportation by air and when it has a magnetic field strength capable of causing the deviation of aircraft instruments. Any magnetic material with a measurable field strength greater than 0.00525 gauss at 15 feet is prohibited from air transportation. An article is not restricted as a magnetized material if the field strength observed at a distance of 7 feet is less than 0.002 gauss or there is no significant compass deflection (less than 0.5 degree).

The postal service seems to say something similar when it comes to shipping them by air.

So, if you have a minibot that you expect to take on an airplane that uses magents, check to make sure it doesn't cause any compass deviation at 7 feet. If it does consider shielding the magnets in a steel box. I suspect it needs to be checked as baggage but don't know that for sure.

Anyone have experience taking strong magnets on airlines? Ours are 1" cubes of Neodymium so strong is an understatement!

[Jeffy]

I haven't ever directly taken raw magnets on an airplane, but I have flown a with small combat robots (150g-3# divisions) and may have some advice to anyone trying to bring robot parts on an airplane.

The best thing you can do is disconnect all the wires you can. The FTA ussualy gets unhappy. One time, they unpluged my battery charger from its power source even though neither were plugged into anything. Then procced to tie both ends of the wires in a knot, that wasn't fun.

Next: provide a small letter for the person that will check your bag. Include what you are doing, the organization name, and what the bot is supposed to do. Include a full list of all the robot parts in the bag. I have recieved a "cool!" on these letters before, and a "congradulations!" on the back of the note they like to put in your bag to let you know they checked it.

Hope this will help some teams, and sorry I don't have anything specifically about high powered magnets.

[MrForbes]

Make sure the guy with the Nixie watch is NOT the same guy checking the bags containing the minibots!

http://www.youtube.com/watch?v=m4R3hODnTGo

(my brother made that watch)

[David Brinza]

That 5 mGauss limit at 5 m might be an issue.

If you postition additional magnets to form a quadrupole arrangement, the field will drop off more rapidly with distance (1/r^4) than for a magnetic dipole.

You can also look into mu-metal shielding. You'll need to degauss the shield first.

You can use Boy Scout compass to test for excessive fields.

[Al Skierkiewicz]

Dale,
I would think the Tetrix battery would raise some eyebrows as well.

[Jeffy]

Originally Posted by Al Skierkiewicz

Dale,
I would think the Tetrix battery would raise some eyebrows as well.

Explain what it is, and you shouldn't have a problem as long as its checked. I have traveled with NiCad, NiMH, and Lithium-Polymer batteries.

[DavidGitz]

About 7 years ago, some students I know from my college were traveling by air to an IEEE Robotics competition. Their robot had a lot of exposed wires and circuit boards. Even though they were checking it in a container, TSA made them take their robot completely apart and they had to rebuild it at their competition. I think this was an extreme situation and there aren't as elements on the minibot that can be "scary" to TSA, but on the same hand I would do what it takes to not have it go through TSA.

[EricVanWyk]

Originally Posted by Al Skierkiewicz

Dale,
I would think the Tetrix battery would raise some eyebrows as well.

I recently traveled with comparable batteries. There is a limit of two "large" batteries per person, where "large" is really difficult to figure out from their web page. I played it safe and assumed that mine were large, and shipped the other 30 cells.

The rules are pretty wonky, so be sure to check out the TSA page.

[DonRotolo]

To emphasize what David Brinza wrote: Magnets can be put inside a magnetically-shielded* box to reduce external fields.

*Magnetic shielding is accomplished by using any material that conducts magnetism. Steel, iron,nickel can be used. Mu Metal is a special alloy that is hyper-conductive to magnetism. It's a bit costly and hard to find - you might get some from around the picture tube of an old CRT monitor or TV - but a small steel box, surrounded by a larger steel box, all put inside your checked bag, should have a negligible field at 7 feet (don't assume - check it. Your pilot depends on his instruments, and if your magnet is messing with that, it could be your life at stake).

Minibots can be checked. Just disconnect everything from everything as much as possible, and pack the batteries separately. I'd hesitate to bring them as carry on.

[MrForbes]

Do they still use magnetic compasses for navigating airliners? Hmmm....

(as I sit staring at a WWII vintage military aircraft compass)

[Dale]

It's just an FAA regulation. They do have them as backups, though.

[Al Skierkiewicz]

On another note...
Everyone has heard that the magnetic pole is drifting right? I think Miami recently had to renumber their runways since the declination has changed so much.

[MrForbes]

My wife mentioned it this morning. Really.

[flameout]

As someone interested in aviation (and flight simulation), I can answer this:

No, modern jet airliners do not depend on magnetic compasses, but rather have at least 2 Inertial Navigation Systems.

Inertial Navigation Systems find true north by detecting the earth's rotation during an alignment phase (while the aircraft is still stationary). They contain 3 axes of gyros (usually laser-ring gyros) and 3 axes of accelerometers. Using these, after alignment, they keep track of their current orientation and position.

Many airliners do have a magnetic compass as a backup -- but they're inaccurate if you are turning, accelerating, or changing altitude (not sure on the last one).

Other sensors, however, may internally use magnets. Also, a minibot could latch itself onto the aircraft's frame...

Of course, the only things that matter here are the regulations, but I just had to say this .

I hope your minibot makes it safely to your regional.

EDIT: Forgot to mention that since aviation still uses magnetic direction (that is how runways are numbered, and what any aircraft smaller than a jet airliner would use (an aviation-grade INS is probably way more expensive than a Cessna)), the Flight Management System has to use a database of magnetic variations to convert true north back into magnetic north. On at least some planes (the MD-11 at a minimum), the pilot has a switch for true/magnetic headings.

EDIT2: I should have known better. Aluminum isn't magnetic. Thanks to jgw for pointing that out. The minibot couldn't latch onto the aircraft's frame.

[Jim Wilks]

Originally Posted by flameout

Also, a minibot could latch itself onto the aircraft's frame...
.

Given that aircraft are predominantly made of aluminum, how is this possible?