a while ago.
Try searching on 'phone'.
IIRC thgere have been at least two, possibly three instances of
programming going wild, one just before the phone started to ring,
another when the phone was tossed with the transmitter, in the flight
box, in the car, on the way to the field.
Those are the only two that seemed to be genuine 'it happened to me' but
of course everybody had *heard* of someone who knew someone...
And zillions of people, myself inclded, who had kept a phone in their
breast pocket whle flying, and taken a call, although I have to admit
that was NOT a computerised transmitter....
A couople of points emerged from teh discussions - again this is memoy,
so check out yourself waht was said.
The first is that the signal strength of a mobile is increased if it is
far away from a base station. The second is that the transmitter is
LARGELY inactive apart from the 'I am here base station, if anyone wants
me' periodic registrtion call, unless the phone is actually in use for
a call, the thiird is that the frequency of a mobile is up ariund a Ghz,
way different from teh 30-80 Mhz region used by the model avionics, and
teh fourth was that I *think* no one had a tx go wild except in teh
sense of broken programming, but my memory is hazy here, and teh fifth
was that teh tx wasn;t switched ON in teh case where it was in teh back
of teh car, but it screwed the NVRAM/EEPROM whatever anyway. Allegedly.
I think the consesnus was that the BMFA rules are way over cautious, and
beyind a few inches it wouldn't be an issue. Its very very rare, but has
happened at least twice, and no one is really sure of the mechanism.
And that is the problem. It really does seem to have happened once or
twice, but by and large people take calls while flying with absolutely
I think there is just enough evidence to suggest it CAN happen.
The REAL urban legend IMHO is cellphones and exploding gas stations.
But cellphones are still banned from use in all UK gas filling stations.
I looked into this with a friend of mine experienced in both telephone and
R/C. He said he'd heard the stories too but could not nail anything
definitive down. However, one thing he did glean from his research was that
the phones in question were of the GSM type.
Of note are the facts that the GSM phone does change it's TX power dependant
on range to the nearest cell. Up to 20 watts has been mentioned but I don't
know how true this is. And the phone does periodically send out short
bursts to maintain it's "knowledge" of the local cells.
At the time of the reported problems they were quite popular in Europe and
almost non-existent in the US. However, they have become more prevalent in
the US. But like with everything else, technology has improved considerably
since then and it is possible the reported problems have been engineered
out. Intentionally or not!
I'll differ with that opinion. To say that it "seems" to have happened
once or twice leads to suggest that it CAN happen is how misinformation and
then Urban Legends get started and take on a life of their own. What is the
statistical ratio for "once or twice" in how many flights and cell phone
uses over a give period of time? Infinitesable (sp?) at best.
I'll bet that more people crash from accidentally dropping their
transmitters while flying that do those who "think" a problem occured due to
cell phone use.
What is being reported is technically "anecdotal" evidence which carries
no weight at all for proving, or even suggesting, the link between cell
phones and TX's.
MY anecdotal evidence is that I have used my cell phone WHILE FLYING
(hands free ear bud) as well as to use it while others have been flying and
have NEVER seen a glitch of any sort. Since you won't accept that as proof
that cell phones don't affect TX operation, why then would I accept YOUR
anecdotal "evidence" as being proof that cell phones DO affect TX
Personally, I'm waiting for some Expert class Ham type guy who knows
what he's talking about to do some actual tests with his high-dollar Ham
radio equipment and publish a report complete with notated test results and
at various frequencies. I would MOST like to see the AMA do this kind of
comprehensive testing because it would be to their benefit to find out if a
problem "may" exist that could affect a future personal injury pay-out.
Until then, all we have is a bunch of old ladies making things up as
they go along.
First of all, it is certainly possible to affect computer circuits and
RAM with high signal strength radio fields.
So it is not that this is impossible according to the laws of physics as
we know them.
The fact that it is so rare implies either
(i) that its total bollocks as you suggest
(ii) that the conditions for it to occur require two or three unlikely
things to happen all at once.
Now I am a fully qualified electronic engineer, and believe me, the
latter is in my opinion the most likley.
It probably needs a combination of a particular frequency, very close
proximity, a particular orientation of a particular phone to a
partiucular transmitter and an incoming phone call from a distant base
station to do it.
However the conicindence of someone receiving a call while flying and
exactly the half second before it rang (consistent with strong exchange
between phone and station) and subsequent discovery post werck, of
scrambled model memories, seems a little too precise to be discounted
out of hand.
Its rare, its very unlikley, but I believe it has happened as many as
two or three times.
You may think its so rare as to be completely not worth bothering with.
Frankly I would not disagree. However the BMFA at least have felt tht it
is sufficiently strong a possibility to recommend a ban on carrying
transmitters and mobile phones together while flying.
I take no position on this, other than to insist that it is certainly
possible. I've seen computers reboot under the impact of a strong police
band transmitter. Field strengths from a couple of watts or more of
microwave energy at very close wuarters - a few cm or so - are extremely
high. Enough to induce a few volts into otherwise robust circuits, and
DRAM and NVRAM and EEPROM are not THAT robust.
Thanks for all the input guys.
Reason for the ?
I had words with committee members at one of the clubs I belong, as they
have introduced the rule no mobiles in flight area.
I will of course obey but said I don't agree.
Another club I am a member of has no such rule and pilots
are just careful when using phones near trannys.
Fact is many flyers are on call when out and this stops them flying.
It seems the jury will be out for a long time over this ?
However I do think that many have taken this inc' the UK's BMFA far to far.
----- Original Message -----
Sent: Wednesday, January 07, 2004 10:56 AM
Subject: Re: Mobile phones & computer Tx?
Well all of my phones were always of the CDMA variety, not GSM. I have
since gotten a GSM phone but have not done much flying with it on hand.
I'll remember to keep it away from my tranny when flying, just in case.
We've had two cases where computer tx's have had problem immediatly
before a call arrives.
Put your mobile next to a speaker and turn it on or off and you get
buzzing interference, thats the problem, not the actual conversation.
It des away within 1m, but if you fly with the phone in front pocket
it within a few 10's of CM and can be a problem with some TX (ff9 in
the two cases, maybe others are better shielded)
Sounds like a good rule to me.
Not because of any mythical interference issues, but because cell
phones are a known distraction.
How many times in the average work day do you see some dolt yakking
away on the cell phone while screaming down the interstate doing 80 or
How many times have you had to _avoid_ that same dolt because he was
paying more attention to his conference call than to traffic around
Many states are busily enacting legislation to prohibit cell phone use
when the vehicle is in motion, and for very good reason.
I don't worry about a cell phone changing the programming in my
I _do_ worry about the idiot who answers a phone call while flying his
DA 150 powered 30-odd percent aerobatic ship.
Flying models isn't the most difficult task in the world, but it is
more difficult than driving the family bus down the road.
If talking on a cell phone while driving can be dangerous (and it has
been so demonstrated countless times), then certainly yakking on a
cell phone in the pits (or worse, when flying) is a really bad idea.
Doesn't matter if you've "got away with it before", it's still a
really bad idea.
I think on-call folks ( and I am in that category every third week)
need to put the cell phone in the car when they've got a transmitter
in their hands, because there is no good reason to put the other folks
at the field in jeopardy simply because the cell phone addicts are too
busy being busy to pay attention to basic safety : keep your mind on
what you're doing.
The House Of Balsa Dust
Coincidence? perhaps, but a club member recently had an arm in bandages.
His large 30cc motor was idling with TX (40Mhz) and Nokia Cellphone on bench
close to model. Friend reached across top of model toward bench, just as
cellphone rang, motor went to full throttle and model lurched forward
against restraint. Movement against restraint at full throttle was enough to
cut several slices into his forearm. He had not touched TX nor moved
throttle lever from the idle position.
Enough for our large club to continue to ban cellphones from flight line.
Alan's Hobby, Model & RC Links
I'll chime in with my own experience with the RINGER on a phone (an
old fashoned one with an electromagneticly driven bell). I had a
floppy disk lying next to the phone when it rang and it scrambled the
data on the disk. Now I know the Eeprom storage mechanism is totaly
different from that used on a floppy; nevertheless, I would suspect
that the vibrator or similar electrfo-mechanical device on a cell
phone would be more likely to create a field that would be strong
enough to affect storage media than the RF signals from the cell tower
or the phone's transmitter. I don't have the equipment to test the
field strength generated by the ringer, but it wouldn't be difficult
The ringer on an old conventional phone has nothing to do with RF. It's the
magnetism that zapped your disk; there wasn't a single RF blip in the area.
Comparing the two situations is like comparing, well, apples to oranges.
What I was suggesting was that the electro-magnetic field from a
ringer is much stronger than the RF field from a cell. I pointed out
that the two media are quite different. Having had some experience in
VLF and the difficulty in shielding in that spectra, I think the field
from a ringer/vibrator is much more _likely_ to couple to the internal
circuitry of a transmitter than a Ghz signal. A relative assignation,
easy enough to check: did the event happen before, after or during the
I wonder what has to happen within the memory circuitry for parameters
to be altered- noise on the supply bus, switch interface, strobe
lines? Perhaps in combination with marginal battery charge? It ought
to be reproducible, and as potentially harmful as the proported
incidents are, I would think it should be investigated beyond the
modestly informed speculation I'm offering.
I will give $1000.00 to the first person to prove that a cell phone at the
field was responsible for am R/C crash do to electrical interference from
said cell phone. (USA only as I am unfamiliar with the world model freqs.)
That being said, don't mistake lawyering up with fact. The Futaba web site
is an example of that, gas stations are another.
I suspect the same guy that crashed when the cell phone rang would have
crashed do some other imagined "glitch" in the absence of a cell phone.
Right after a crash you more often than not hear those famous words "who
turned on their transmitter", to give them an additional excuse is
Is it worth the risk? We had some issues with cellphones at work
affecting kit (making a press that could deliver 100psi judder, even
when in standby, and would you want to put your fingers near that just
in case!!), and the NHS have done a really comprehensive study (but it
cost's £125 a copy so I'm quoting from memory as it's not here with me
Cellphone radiation is at it's highes when it's trying to establish
contact with a cell mast, be that at the start or end of a call or
when it checks in periodically to report it's still in the cell.
At the start of a call the phone is paged and it responds, saying I'm
here, this signal is a higher strength than the signal during the
conversation as it does not know how far it is from the mast,
similarly the checkin call every so often is a stronger pulse as the
phone doesn't know what cell it is in.
Getting back to the NHS thing, most equipment is not affected by a
phone more than 3m away, (it's an inverse square law rule) but as you
don't know where the sensative equipment is they ban them totall,
(might be other side of the wall your leaning against).
That signal pulse WILL affect equiment the question is will your
equiment accept it (it should) and will it be affected (it should
not), but getting back th the point is it worth the risk.
Make a rule no cellphones on the flight line, and be aware that iot
may present a problem in the pits maybe even moving out and away from
the pits if you get a call. It might be a bit OTT but it's no more
than not standing in front of a prop, yes there is a risk, but why
tempt fate and follow bad practice.
I liked Futabas opinion on interference.
Interference is no problem, the FCC makes sure that the frequencies don't
interfere with one onother.
But still, keep a mobile phone 1000 ft. away ?!
Its a shame that they can't say what they want without disclaiming for legal
reasons. What is this world coming to? *disclaimer* I accept no responsibility for any eye-damage or mouse-itis
you may get from reading/scrolling this. Neither incidental nor
Futaba is a registered trademark of Futaba Inc.
FCC had no part in writing this message
I love lawyers (sarcasm not intentional)
We can make it fly...
| I will give $1000.00 to the first person to prove that a cell phone at the
| field was responsible for am R/C crash do to electrical interference from
| said cell phone. (USA only as I am unfamiliar with the world model freqs.)
| That being said, don't mistake lawyering up with fact. The Futaba web site
| is an example of that, gas stations are another.
| I suspect the same guy that crashed when the cell phone rang would have
| crashed do some other imagined "glitch" in the absence of a cell phone.
| Right after a crash you more often than not hear those famous words "who
| turned on their transmitter", to give them an additional excuse is
| > > > The ringer on an old conventional phone has nothing to do with RF.
| > the
| > > > magnetism that zapped your disk; there wasn't a single RF blip in
| > area.
| > > > Comparing the two situations is like comparing, well, apples to
| > > >
| > > > MJC
| > > What I was suggesting was that the electro-magnetic field from a
| > > ringer is much stronger than the RF field from a cell. I pointed out
| > > that the two media are quite different. Having had some experience in
| > > VLF and the difficulty in shielding in that spectra, I think the field
| > > from a ringer/vibrator is much more _likely_ to couple to the internal
| > > circuitry of a transmitter than a Ghz signal. A relative assignation,
| > > easy enough to check: did the event happen before, after or during the
| > > ringing?
| > >
| > > I wonder what has to happen within the memory circuitry for parameters
| > > to be altered- noise on the supply bus, switch interface, strobe
| > > lines? Perhaps in combination with marginal battery charge? It ought
| > > to be reproducible, and as potentially harmful as the proported
| > > incidents are, I would think it should be investigated beyond the
| > > modestly informed speculation I'm offering.
| > Well I for one and I am sure many others would like to see an in depth
| > study done if there is a real problem. We are talking safety here.
| > John