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Topic: Why are Magnets not allowed in an airplane? (Read 51020 times) previous topic - next topic

otzi

Hi

I always when I go on an airplane I think why cant I take Magnets in my suitcase? The magnets would be far enough away from any electronics. Hope you can help me.

DuaneB

No idea, but maybe its more to do with the effect they have on luguage scanning on the ground ?

Not that anyone has ever stopped me from taking them on planes - I have a mag mount arial which I travel with - over 60 countries and counting.

Duane B
Read this
http://rcarduino.blogspot.com/2012/04/servo-problems-with-arduino-part-1.html
then watch this
http://rcarduino.blogspot.com/2012/04/servo-problems-part-2-demonstration.html

Rcarduino.blogspot.com

John_S

The reason is that the aircraft's magnetic compass is, well, magnetic. Any significant magnetic source can influence which way the compass turns. However, any magnet you can carry in your suitcase would practically have to be in the flight deck to cause any problems, and the fact that most navigation is done by GPS and IRS (both independent of sensing magnetic north) I don't think a magnet on board is going to cause any problems.

I think it's just like cell phones on airplanes... it is easier just to ban their use than prove that they absolutely will not cause a problem.

DuaneB

On many of the Emirates planes you are actively encouraged to use your mobile -

http://en.wikipedia.org/wiki/AeroMobile

Duane B
Read this
http://rcarduino.blogspot.com/2012/04/servo-problems-with-arduino-part-1.html
then watch this
http://rcarduino.blogspot.com/2012/04/servo-problems-part-2-demonstration.html

Rcarduino.blogspot.com

otzi

So in a suitcase it would not cause any damage but its safer not to take them. Thx for your replies.

MarkT

"When accepting magnetized material,
aircraft operators should ensure that the shipper verifies that
the maximum field strength is no greater than 0.00525 gauss when
measured at 15 feet from all surfaces of the package."

That's 0.5 uT (micro tesla) at 5m in 20th century units!

Since field-strength falls off as 1/r^3 for a dipole that means strong permanent magnets (upto 1.2T) should be a few cm across or less.  The earth's field is between 25 and 65 uT so 0.5 micro tesla represents a degree or so of error.
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spcomputing


So in a suitcase it would not cause any damage but its safer not to take them. Thx for your replies.


There is a sweet spot (or un-sweet) in a harmonics that *may* affect other circuitry.  Usually, it is a high energy pulse of some variety (HAM guys might understand the Linear and old automated garage doors in the neighborhood)  Every effort has be put into isolating this PED or personal electronic devices interference (on aircraft) and they have come up with nothing.  Apparently,  Air UAE is having fun not giving in to the consensus of the precautionary principle in banning everything that they do not understand.

So, no, you will not find a reasonable scientific (reproducible) that will support a one telsa object doing anything to aircraft avionics.

MarkT

If an aircraft's magnetic compass is known not to be functioning I suspect the aircraft cannot be flown due to regulations (GPS is many orders of magnitude less reliable than the earth's core!)

A 1T magnet 3cm across is pretty safe, a 1T magnet 1m across would totally wipe out the aircrafts compasses.  Arguing by analogy with RF interference is bogus.
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

kf2qd

It's more of an annoyance to security. My wife has a Bible cover with a magnetic flap. the Xray scanner will see it - the magnet plays with the X-rays, and they want to check it and seem a bit annoyed but they have never said she can't have it in her carry-on.

Llia

Hi

I always when I go on an airplane I think why cant I take Magnets in my suitcase? The magnets would be far enough away from any electronics. Hope you can help me.
I can only assume it's because of it's effect on security scanning equiptment which relies on forms of radiation to generate an image. The radiation is susceptible to interference from magnets that can divert/alter the path of the radiation making the image unclear. I was considering wearing a magnetic button the neodymium boride variety to see how it would go but the threat of an alterate method of security check ie: the strip search has deterred me thus far.

As an x-ray helper/developer I was told to avoid wearing metal and magnets on my person during the filming when securing the subject as either could  cause interference. I also wore lead lined gloves and apron.

MarkT

Large magnets can make an aircraft crash, that's the bottom line, the onboard compass and dead-reckoning is the
last line of defence for navigation when other instruments fail.  A good compass can be accurate to a small
fraction of a degree if calibrated correctly and no random magnets are in the vicinity.  Of course if you are
near one of the Earth's magnetic poles it won't matter, but that's the reasoning.

Magnets don't interfere with X-rays themselves, but can affect the X-ray tube's electron beam, defocussing it.

That's a reason for hand-inspection rather than preventing the magnet going on-board.  Most magnets in pieces
of equipment are small and reasonably well contained (they are part of a magnetic circuit in a motor, typically).

http://www.intemag.com/shipping_magnets_by_air.html?url=shipping_magnets_by_air.html&info_id=14
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

Boardburner2

#11
Mar 22, 2017, 10:00 pm Last Edit: Mar 22, 2017, 10:15 pm by Boardburner2
"When accepting magnetized material,
aircraft operators should ensure that the shipper verifies that
the maximum field strength is no greater than 0.00525 gauss when
measured at 15 feet from all surfaces of the package."

Your average carry on passenger cannot verify that and customs do not have readily available equipment to check.

Much easier to have a blanket ban.
I doubt the like of fridge magnets would be a problem but the neodymium etc could be, they can also look like batteries on x rays so will be investigated.

It's more of an annoyance to security. 
Correct.

Robin2

Why is this Thread attracting so much attention?

...R
Two or three hours spent thinking and reading documentation solves most programming problems.

Boardburner2

It has been quiet recently.
I suspect boredom.

Hoping for something humerus to pop up.

GoForSmoke

There is an altitude/Above Ground Level sensor that uses an electrical difference from about 2000 ft down that at least used to get screwed by people's personal electronics. I'm fuzzy on the details, knew the intro level decades ago when personal electronics used a lot more power than now. Remember when things had to be shut off only during takeoff and landing but not at altitude? That's why.

The newer avionics either aren't affected or use other sensing (lidar?) but get on an older plane without them and hear the pilots yelling "Yeee-iiiiiii!" coming in to land as the height gauge numbers jump up and down. That would be a good day to have a bulletproof life insurance policy and a nice photo of yourself for the funeral.
1) http://gammon.com.au/blink  <-- tasking Arduino 1-2-3
2) http://gammon.com.au/serial <-- techniques howto
3) http://gammon.com.au/interrupts
Your sketch can sense ongoing process events in time.
Your sketch can make events to control it over time.

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