
Ask HN: Are mobile phones on a plane taking off or landing really dangerous? - rakkhi
Are there any actual studies and detailed research with proof that having my mobile phone on during take off or landing provides and increased risk of the plane crashing (or other adverse reaction?)<p>I mean logically if planes did not have sufficient shielding for this would a terrorist not just bring about 1000 phones (say its for export for sale) as hand luggage and just leave them on? Also some planes now now allow mobile phones to be used on board.<p>Things that have been done for the sake of it or have continued because that was the way it has always been really annoy me. And I really hate having to switch off my phone and my RSS reader getting dirty looks for fellow passengers.
======
eli
From the press release for a Carnegie Mellon study in 2006:

 _"We found that the risk posed by these portable devices is higher than
previously believed," said Bill Strauss, who recently completed his Ph.D. in
EPP at Carnegie Mellon. "These devices can disrupt normal operation of key
cockpit instruments, especially Global Positioning System (GPS) receivers,
which are increasingly vital for safe landings." Strauss is an expert in
aircraft electromagnetic compatibility at the Naval Air Warfare Center in
Patuxent River, Md._

<http://www.cmu.edu/PR/releases06/060228_cellphone.html>

It's true that no crashes have been positively linked to cell phone use, but
it's also true that black box recorders don't measure RF interference so it
would be difficult to do so.

edit: and here's a link to the whole paper
[http://spectrum.ieee.org/aerospace/aviation/unsafe-at-any-
ai...](http://spectrum.ieee.org/aerospace/aviation/unsafe-at-any-airspeed/0)

 _In one telling incident, a flight crew stated that a 30-degree navigation
error was immediately corrected after a passenger turned off a DVD player and
that the error reoccurred when the curious crew asked the passenger to switch
the player on again._

~~~
MichaelGG
Seems like GPS for landing is poor dependency, considering how easy it is to
jam GPS...

~~~
borism
That's why RNAV (GPS) approaches are still not allowed (for commercial
flights) AFAIK.

30 degree error has nothing to do with GPS though. Probably DVD player
interfered with Localizer signal.

~~~
mipnix
GPS approaches are allowed, FWIW.

I'm also not sure the localiser signal was involved since I don't think the
crew would have gone to the back to get the passenger to mess around with the
DVD during an approach.

------
mipnix
I flew for the airlines.

The problem is not your everyday takeoff and landing. The problem arises when
the weather deteriorates to near zero visibility and the crew is relying on
instrumentation to find that strip of pavement, at 130 knots.

Instrument approaches rely on a narrowing volume of radio signals, the closer
one is to the runway. The tighter the signal, therefore, the greater the
deviation should something go wrong. Think of threading a string through a
funnel, if you touch the edges, you lose. Now do it on a trampoline while
someone else jumps on it. I assume we can all agree that wildly porpoising a
200k lb jet, 400 from the ground, chasing a signal, is not a good idea.

Vehicles on the ground are prevented from encroaching on the approach signal
area, when aircraft are shooting approaches in reduced visibility conditions,
to prevent them for interrupting the signal. In the cockpit you can see your
signals fluctuate if someone does cross that threshold. It happens.

When visibility is good, it is a non event but when you can't see jack, having
your guidance just start dancing around, gives one moments of pause.

The phones do interfere in some manner. TO what degree, I can't say. I have
forgotten to turn my phone off before takeoff and get the annoying beep in the
headset when we descend into an area with coverage, so something is going on.

The reason they ask you to turn it off is because they can't tell you its
okay, because they haven't tested it. They can't say, well turn it off if it's
cloudy or if the bases are below 300'. Some departures and arrivals require
precise navigation, even in good weather, for traffic flow reasons. Missing a
fix on departure or arrival could cause traffic alerts or aircraft deviations.

All rules exist for the worst possible scenario. Not the milk run. But how do
you explain that to the traveling masses? You should be more concerned with
the fact those little dixie cup oxygen masks they instruct you to put on in
the event of a decompression, won't actually supply you with oxygen when the
shit hits the fan at altitude. It's a partial pressure thing.

That's just between you and me...

Edit: At the end of the day, it is the law. If the crew is having a bad day
and has a stick up their ass, they can make your day a lot worse. You need to
ask yourself, does ignoring the rule, no matter how inane you think it is,
really make a body cavity search worth checking the latest XKCD update?

~~~
thewileyone
Isn't the avionics room under the cockpit shielded to sustain operations
through lightning storms, signals bouncing off the ionosphere, solar flares,
etc.?

I've flown commercially with my phone left on and privately in Cessnas and I
haven't experienced anything negative. My dad's a pilot too by the way and he
said that there's no supporting evidence, but this is a just small rule so
might as well comply.

~~~
mipnix
There is no supporting evidence. That is part of the problem. The FAA has
enough on their hands trying to get the air traffic control system into the
latter half of the twentieth century, without trying to test for every stray
signal and how it might affect the navigation. A blanket policy, restricting
all devices does that.

The wiring is shielded to an extent but there is no special safe room for the
avionics. A lot of it is in the nose, right in front of the crew. It is, after
all, a very thin tube of aluminum we are all shooting around in. Weight is
something to be avoided.

------
fizx
The plural of anecdote is not data, but stories are fun.

Last Christmas, I was on a multi-hop flight back to SF from the east coast. We
were going to be landing in Vegas, and I was talking to a flight attendant.
She mentions that conditions in Vegas were a little crazy, as the runway
doesn't drain properly and crosswinds are common.

As we're preparing to land, the captain gives the usual speech. It's going to
be a little rocky on the landing; there's a sleet storm, etc.

We're making our approach, and the flight attendant gets on the PA. "Someone's
cell phone is on. Turn it OFF NOW." A minute later: "Someone's cell phone is
still on. I need EVERYONE to doublecheck their phones, and get that phone
switched off!"

We ended up diverting to Phoenix, because the pilot did not feel comfortable
making an instruments-only landing. His announcement was the only time I've
ever heard a pilot sound audibly rattled on the PA.

~~~
endtime
Did it turn out that anyone actually had his phone on?

~~~
borism
How do you imagine they would find that out?

Probably the problem was that during approach pilots had the usual GSM buzz in
their headphones while trying to communicate with ATC.

Do you really want your pilots not to hear ATC instructions on take-off,
landing or taxi? Like not hearing landing clearance, or which runway exit to
use, or what other traffic to lookout for.

Do you even know what was the main cause of the deadliest air disaster (583
dead)? That's right, not hearing ATC instructions.

~~~
elai
To be able to hear the gsm buzz in their headphones, the cellphone would have
to be on their person, turned on, and be about send/receive some sort of call
or data. If a cell phone from a distance away can cause a gsm buzz, then being
in an area that has cell phone reception would cause the buzz and they need to
design their headphone systems better.

------
spokey
If they were really dangerous, I suspect they wouldn't let you have them in
the cabin at all. "Everyone turn off your phone" isn't the level of safety
compliance major airlines typically rely on.

~~~
SpikeGronim
If they were really dangerous, Al Qaeda would be using them to bring down
planes.

~~~
notahacker
That would be like al-Qaeda operatives trying to cause road accidents by not
recalling their Toyotas. [Theoretically] increased risk != an effective
weapon.

------
mgod
Please, please let's let the airlines keep this rule no matter how little it
has to do with safety. If you get an honest answer from a pilot, they'll tell
you this was never covered in any flight school, and they usually leave their
phone on, but can you imagine a flight where that business guy who just
doesn't get it spends the whole time on flight talking on the phone?

~~~
DrJokepu
Consider this: you're on an eight hours long flight and you need to make a
really urgent call. There are no technical reasons why you wouldn't be able to
do so, but it is forbidden because some people would abuse it and wouldn't be
considerate to other passangers. It's not the phone that should be banned,
it's being an inconsiderate prick that should be disallowed.

~~~
almost
But until we figure out a way to ban being a prick I'll take the blanket phone
ban.

And what is this urgent call about anyway? Maybe to you it seems urgent and to
me it just seems like you're being inconsiderate.

~~~
cjg
Perhaps you are an eminent surgeon and someone is calling you for a life or
death consult.

------
mikeryan
There's a pretty robust wikipedia article about this

<http://en.wikipedia.org/wiki/Mobile_phones_on_aircraft>

~~~
rakkhi
Thanks for the link, a few good quotes from there:

Now this I can definately belive: "the report concludes that the primary
reason for the ban on cell phone use in flight is that neither the FAA nor the
FCC are willing to spend the money to perform conclusive safety tests. "

God flight attendant observations? Thats the evidence that is reliable? How
could you isolate for all the other factors? "However a few reports state that
anomalies were observed to appear and disappear as the suspect device was
turned on and off which would indicate a high degree of correlation."

"Degrees of correlation or confidence were not among the data summarized in
the report."

"There is no smoking gun to this story: there is no definitive instance of an
air accident known to have been caused by a passenger's use of an electronic
device. "

This is my point - are we still in 1984? "will exceed demonstrated
susceptibility levels for equipment qualified to standards published prior to
July 1984"

BBC report: "most of the evidence is circumstantial and anecdotal. There is no
absolute proof mobile phones are hazardous."

"Whether interference from small battery-powered devices should have any
influence on electronic systems that should be designed to fly through
lightning storms without failing is often disputed by critics of the ban."

~~~
eli
_This is my point - are we still in 1984?_

No, but I'm pretty sure the point is that planes from 1984 are still in use.

~~~
count
The airframes might be, but they definitely have been upgraded/retrofitted
with newer gear.

My favorite is the industrial, hardened switch for 'Internet Off' on Delta
flights with onboard Wifi now (which I can't believe I can't find a picture
of!).

If I can use WiFi on the plane while it's flying, why not while it's taking
off and landing?

~~~
hcho
Because if something goes wrong the pilots have a lot more of time for a
corrective action during flight. Not so much during take off and landing.

------
irons
I'd like to know what drove the relatively recent policy shift around
demanding that phones and other devices be "completely off" at takeoff and
landing, with airplane mode deemed insufficient. From a visual survey of
people turning their phones on later, this prohibition seems to be obeyed
mostly by one teenager on JetBlue with an iPod once.

~~~
julianz
I've noticed exactly the opposite on recent flights between NZ and Australia
-- they're now a lot more tolerant about having mobiles in flight mode (and
specifically say so in the pre-flight announcement) and they let you turn your
phone on as soon as the plane has landed. Previously you had to wait until you
were "well inside the terminal".

~~~
irons
"Well inside the terminal" comes as a surprise -- in the US, the carriers have
traditionally tolerated everyone snapping their phones on within a few seconds
of touching down. Which is really just another oddity, now that I think about
it.

------
artmageddon
This is strictly anecdotal evidence, but I'll throw in my 2 cents here. I have
a private pilot certificate and am working toward an instrument rating right
now, which involves being in continuous contact with air traffic control,
flying in low / zero visibility conditions, and relying on aircraft
instruments to guide me on landings.

On numerous(if not all), I've had my iPhone with me, switched on and even in
my lap at times(to use the stopwatch). Occasionally I would keep it in
airplane mode on extended flights, but only to conserve battery life. Despite
incoming calls and SMSs during these flights, not once have any of the
instruments been affected by the phone.

We can all agree that a four-seater Cessna and 767 are very different, but for
nav/comm they all use the same instrument systems. I would find it very hard
to believe that a larger aircraft wouldn't have more shielding / protection
than a simple Cessna with a phone that's just two feet away.

One more thought: Federal Aviation Regulation 121.306 states that no portable
electronic devices are allowed except for: portable voice recorders, hearing
aids, heart pacemakers, and electric shavers. How are the first and last any
different from a phone in airplane mode?

~~~
a-priori
_We can all agree that a four-seater Cessna and 767 are very different, but
for nav/comm they all use the same instrument systems._

Unlike a Cessna, a 767 has a fly-by-wire system supported by a data bus (e.g.
ARINC-429) running the length of the aircraft, often close to the passenger
cabin. Presumably, GSM/CDMA signals could interfere with this.

~~~
artmageddon
I'll admit that I wasn't aware of this, but on the same token, would that
portion of the electronics not be shielded as well?

~~~
joezydeco
The 767 was first built in 1981, long before everyone in the passenger cabin
was emitting microwave-class RF radiation.

The plane itself serves as a very large shield to _outside_ radiation, but I'm
guessing the internal wiring is not RF-shielded because of weight concerns.
Wonder how much it costs to rewire a 30 year-old plane.

~~~
bl4k
It cost $368 Million when the FAA forced operators to replace Mylar insulation
(cause of at least two accidents):

[http://findarticles.com/p/articles/mi_m0UBT/is_10_19/ai_n129...](http://findarticles.com/p/articles/mi_m0UBT/is_10_19/ai_n12941245/)

According to this very interesting IEEE article, it costs anywhere from $1-5M
per airplane, which doesn't include lost business cost:

[http://spectrum.ieee.org/aerospace/aviation/down-to-the-
wire...](http://spectrum.ieee.org/aerospace/aviation/down-to-the-wire/0)

------
Pyrodogg
Another reason I've heard argued by a coworker is that they aren't banning
electronics for the sake of interference, but for your attention.

If anything were to go wrong during a flight, takeoff and landing are the two
times that they want you to be able to react with zero hesitation. If
something goes wrong and you have seconds to react, the less things you're
fiddling with the more likely you are to survive.

~~~
irons
That's not a compelling explanation, considering that you're free to keep your
head in a John Grisham potboiler (as long as it's not a Kindle edition), or
remain fully asleep at takeoff and/or landing.

~~~
Marticus
Well actually I think it's better than jamming the newest (insert band here)
album and not be able to hear much other than that and a very dim amount of
engine noise.

I think it is safe to say it's likely a combination of many things - this
coupled with statistics (as mentioned before, very small % failure rate + very
large flight volume = enough dead people to warrant having them turned off)
seems the most plausible.

Not to mention that someone linked that it could very well be a problem with
the cellular networks - if (hypothetically) you could bugger up an entire
major tower with enough "hop" volume, I can see why the FAA or other
organization would just want to have this as a cover-our-ass precaution, too.

------
runjake
Former avionics tech here. Not scientific, but I've seen CDMA devices
interfere with nav equipment, and GSM devices interfere with communications
system (ala the infamous dat-dit-dah GSM sound over speakers). And these on
nuke-hardened (EMP-shielded) military systems.

These issues aren't going to crash the plane, however with the sheer variety
of cellular devices, it's just a good idea to keep them off.

Besides, you people who can't seem to shut them off are an annoying lot, so
there's also a co-passenger sanity aspect to it. Just leave them off, are you
that addicted to Farmville?

~~~
rakkhi
Not farmville but I enjoy reading on my phone, RSS feeds, kindle books,
Instapaper. etc. Short flights espeically in the EU e.g. 1.5 hours to
Amsterdam on the weekend in great time to catchup on reading. Missing the
takeoff and landing cuts about 30 minutes of reading time.

It sounds selfish and there is enough evidence here that I am now happy to
just turn my phone off, maybe I will just print off some of my Instapaper
articles :)

~~~
borism
There are offline RSS readers, Kindle apps and Instapaper saves can be
exported to various formats.

~~~
rakkhi
It is all offline, I only read in airplane mode on the phone, I use high
contrast mode with medium brightness on the Instapaper app so don't think I
really annoy everyone else, but you do get told to turn the phone off even if
it is in airplane mode (thus no signal in our out) for takeoff and landing.

I just need to go to super offline mode and print stuff out!

~~~
StavrosK
You don't have to turn your phone off during the _entire_ takeoff and landing,
just when the stewardesses come to check you.

Apparently that's the only dangerous part.

------
bl4k
Here is the reason straight from the FAA:

 _"There are still unknowns about the radio signals that portable electronic
devices (PEDs) and cell phones give off. These signals, especially in large
quantities and emitted over a long time, may unintentionally affect aircraft
communications, navigation, flight control and electronic equipment."_

[http://www.faa.gov/news/fact_sheets/news_story.cfm?newsid=62...](http://www.faa.gov/news/fact_sheets/news_story.cfm?newsid=6275)

ie. We don't know, but we are playing it safe. While it is an inconvenience, I
take comfort in knowing that the regulators are erring on the side of caution
when it comes to air safety.

If they are so cautious with the slightest possibility of radio interference
from a 3v device, then I can be assured that the remainder of the plane (ie.
the thing that is flying at 800km/h at 30k feet with 200+ people inside it)
has been checked over and is safe.

~~~
konad
How hard could it be to get 500 phones, put them in a plane and dial them all
?

~~~
InclinedPlane
There are more than 500 _different kinds_ of phones.

That's the problem.

~~~
konad
It's only a problem if the plane doesn't fail.

However, if it fails with those 500 then that's all you need to know to say
"phones can down the plane". If you need more detail you can keep researching.

~~~
InclinedPlane
The plane doesn't fail, it's been done. There are too many variables. The
biggest problem is older electronics and GSM.

------
pyronicide
Mythbusters did a great show on this problem. Here's a link to the results of
the show:

<http://mythbustersresults.com/episode49>

~~~
rakkhi
Thanks for that I was really hoping that Mythbusters had tested it. "It was
found that cell phone signals, specifically those in the 800-900 MHz range,
did intefere with unshielded cockpit instrumentation. Because older aircraft
with unshielded wiring can be affected, and because of the possible problems
that may arise by having many airborne cell phones "seeing" multiple cell
phone towers, the FCC (via enforcement through the FAA) still deems it best to
err on the safe side and prohibit the use of cell phones while airborne."

So that is interesting, wonder if they suggested modern shielded planes. Also
lends credence to ground interferance as the real reason for the "ban"

~~~
cryptoz
But that's the part I don't get; there's no "ban" at all! I can bring a bunch
of phones on the plane and just not tell them about it. If they search my
bags, they'll remove my 200ml of water citing "it's too dangerous" but they'll
leave the cellphones alone.

That's not much of a "ban". So I still disagree that phones could interfere in
any meaningful way with any aircraft's systems.

~~~
mquander
That is a foolish conclusion.

Firstly, if the TSA searches your bags and actually finds a "bunch" of cell
phones, I bet that they will find an excuse to hassle you about it.

Secondly, your own example shows how shoddy this reasoning is; the TSA is not
rational* about what they confiscate and what they don't -- your water isn't
dangerous, and they took it, so why would you trust their judgment on cell
phones?

Thirdly, the cell phone industry moves much faster than the airline security
industry, so it's (vaguely, remotely) possible that some new phone released
yesterday is dangerous, whereas old models aren't; the airlines wouldn't know
the difference. One could say the same for almost all consumer electronics. So
it would be hard to ban "bad" electronic devices and allow "OK" ones, and
probably not worthwhile. Banning them all is an option, but just because it's
a risk doesn't mean it's enough of a risk to be worth addressing.

*At least, they aren't rationally trying to prevent planes from being hijacked or interfered with; maybe they are doing a good job at other things, like making people feel warm fuzzies about security.

~~~
CWuestefeld
_it's (vaguely, remotely) possible that some new phone released yesterday is
dangerous,_

That's no greater a possibility than for my netbook, or my wristwatch, for
that matter. Why pick on phones over other electronics?

(I suppose the answer is to see your previous paragraph regarding rationality)

~~~
mquander
They don't pick on phones over other electronics. On every flight I've been
on, they ask passengers to shut off "all portable electronic devices,"
including things that often don't even communicate over a network, like CD
players.

------
iuguy
Two things:

1\. Using a mobile phone isn't generally dangerous providing everything else
on the plane works fine and nothing would be interfered with if it wasn't.

2\. Cell handovers at 30,000ft with an air speed around 500mph are really,
really hard.

The reasons for turning your phone off during takeoff and landing are wide and
varied, but the long and short of it is that it effectively counts as security
theatre. Take off and landing are the two most dangerous bits of any flight.
If anything goes wrong they do not want people tweeting "OMG IM GOING TO
DIE!!!!", they want them focused on bracing for impact. That's not the only
reason (or necessarily a major one) but you get the idea.

~~~
mattmiller
Since most phones are CDMA now I think the dangers of interference are much
much lower. I have always suspected that carriers help promote this myth to
reduce network overhead from point 2 above.

~~~
cromulent
I'm fairly sure most phones are GSM.

[http://en.wikipedia.org/wiki/Comparison_of_mobile_phone_stan...](http://en.wikipedia.org/wiki/Comparison_of_mobile_phone_standards#Development_of_the_Market_Share_of_Mobile_Standards)

------
ax0n
I find it hard to believe that a plane's avionics are sufficiently shielded to
withstand a direct lightning strike, but one person's phone will crash the
plane.

I've heard other explanations, too, such as the fact that too many mobile
towers are line-of-sight at the same time, and the effective ground speed
means you'd hop towers far too often and it'd mess with the phone system.
Multiplied times the number of mobile-phone-carrying passengers in the air at
any given time, I suppose it's plausible.

~~~
rakkhi
That last one is an interesting point, any references to whether it has been
tested?

~~~
ax0n
[http://www.breitbart.com/article.php?id=D8O9BCJ80&show_a...](http://www.breitbart.com/article.php?id=D8O9BCJ80&show_article=1)

FTA (emphasis added): "Existing rules require cellular phones to be turned off
once an aircraft leaves the ground _in order to avoid interfering with
cellular network systems on the ground_."

------
hcho
Leave your phone near a CRT screen or loudspeaker, observe the noise right
before you recieve a call.

The rest is statistics and probability. What's the probability of interference
causing a fatal misreading in aircraft's sensor? Too small. What's the number
of flights world wide? Too big. We would see a number of accidents if everyone
kept their phones on all the time. As a death is one too many, it warrants the
ban.

~~~
cryptoz
I disagree. The airlines claim the risk of death from my water bottle is too
high to allow me to bring the water on the plane. Fine. However, I'm allowed
to bring 100 cellphones in a backpack. They don't care about that, except to
politely ask me to turn them off.

If there was a remote chance of a cellphone causing a crash - more chance than
a bottle with water in it - then they would ban cellphones in flight.

It's very clear that there is no actual risk of interference at all.

~~~
hcho
The water bottle thing is not airlines' doing as far as I know. It's to do
with your countries national security authority.

Emirates allows mobile phones on some of their flights.

~~~
jonknee
> The water bottle thing is not airlines' doing as far as I know.

Neither is the cell phone thing in the US. It's both the FAA and FCC:

[http://www.faa.gov/news/fact_sheets/news_story.cfm?newsid=62...](http://www.faa.gov/news/fact_sheets/news_story.cfm?newsid=6275)

------
greendot
Go fly in a private plane and leave your cell phone on. I do not fly IFR so I
haven't had to rely in my ILS but it does destroy radio communications. Have
you ever heard your GSM based phone pulse and cause noise on a close by
speaker? Imagine that being pumped into your radios and into your headphones.
It is painful to hear. If I was landing when it went off, it could cause me to
react badly at a time when I couldn't afford it. Also, I could miss a call
that there is traffic around.

------
Poiesis
Here's the part that I think about: ok I get that phones could potentially
cause a problem. If that is the case, than we shouldnt be relying on voluntary
compliance. Either it's not a problem--then let people do that they want, or
it's a problem, and you better be telling me that you have a better risk
mitigation than "hope that everyone turns off their phones".

------
steveklabnik
It has to do with FCC regulations. This is terribly handwavy, because I barely
remember the explanation, but basically, they have to make sure that the plane
isn't giving off certain signals and interfere with anything, and the easiest
way to do that is just to tell everyone to switch their devices off.

Hopefully someone can clarify that a bit.

~~~
cryptoz
> they have to make sure

This is the problem, though. They _don't_ make sure! They politely ask you to
turn your phone off. 50% of people comply, 50% don't. If they _actually had
to_ stop the signals, they would ban all cellphones in the cabin. They could
collect them, put them in a lead case with the luggage and move on.

But since they don't "make sure" of anything, I disagree with your
explanation.

------
xyzzyz
Do the cellphones even work in airplanes? I mean, they are pretty far from
antennas, even over civilized area. They also move quite fast, although I do
not really know how much Doppler effect affects the phones' transmitters and
receivers. The plane is also a Faraday cage, thus it may greatly reduce
signal.

~~~
m_eiman
GSM is designed to be usable when travelling in a car, but going much faster
than that will likely cause problems. It's probably problematic that you're
not staying long enough in a single cell tower's range, and doppler effects on
the radio signals will also cause problems (if I remember correctly from my
uni course on the subject).

------
TGJ
As far as I'm concerned, reason #1 to ban cell phones on airplanes,

Who wants to listen to the person beside you talk through the flight on a cell
phone. Your life can be on pause while you fly through the air.

------
Sidnicious
I've heard it summarized thusly:

The aircraft is most likely to hit something during takeoff and landing. Cell
phones, laptops, and other hard, dense, chunks of metal plastic are, in fact,
dangerous when they're flying toward your head.

It doesn't particularly matter whether they pose an electronic threat, policy
would be the same.

~~~
rakkhi
Wouldn't that just mean the policy should be put them away not turn them off?

------
sandis
I was thinking of this 2 days ago, when I decided to leave Runkeeper running
in my pocket :)

------
sswam
I don't want to encourage terrorism, but if someone wanted to destroy an
airplane, they could bring onboard a more dangerous device disguised as a
phone or other everyday 'black box' object such as a laptop. The dangerous
device might emit serious levels of radiation, it might contain a powerful
laser, it might contain explosives. The best defense against 'terrorism' is to
be nice to other countries, help them and don't oppress them.

Usury (national debt), bombing, invasion and economic sanctions (aka
starvation) are not nice. The countries and groups that commit crimes like
those are likely to be attacked. Don't be bad, and no one will want to kill
you.

