Is There Any
Danger Using Electronic Devices on an Airplane?
Do we really need to 'turn off all
electronic devices' prior to take-off and again prior to
A plane can safely
withstand a lightning strike of hundreds of millions of
volts and tens of thousands of amps.
But turn on your iPod and the plane might lose control,
crash and burn?
Electronics - and access to
them - are becoming ever more inseparably a part of our normal
Everywhere, that is, except in airplanes, where some things
are never allowed to be used and others are only allowed to be
used above 10,000 ft.
We're told that FAA regulations
prohibit such devices, and we're lead to believe that they may
dangerously interfere with the plane's operation.
But is any of this actually true?
Let's carefully dissect the disinformation and see what the
reality actually is.
As you know, the airlines have varying
degrees of restrictions on the use of portable/consumer electronic devices on
planes. These restrictions are usually claimed to be due
to FAA regulations, and due to concerns that the electronic
items may interfere with some of the plane's own electronics -
either the instrumentation or perhaps even the actual plane's
Let's first look at what the FAA says, and
then from that reference point, let's consider the validity of the
airlines' concerns about portable electronic devices, then at the
sense (or nonsense) of the restrictions they impose on us.
Does the FAA Regulate Using
How often have you heard the
flight attendants announce 'FAA Regulations require you to turn
off all your electronics before we can close the door and push
back from the gate'? Or 'Due to federal regulations, we must
ask you to turn off all electronics now and leave them off until
we have parked at the gate after landing'?
Is this really something the
FAA requires? Or are airline flight attendants lying to us
every time they make this claim?
Here is the relevant
FAA regulation about using
electronics on flights. To save you the need to
carefully read through it all, it basically says the airlines are
free to decide for themselves what they will and will not allow on
flights, and under what conditions they will allow them.
It talks about prohibiting
some devices during take-off and landing, and about lesser
restrictions below 10,000 ft, but try and find a specific list of
prohibitions or restrictions, and you will fail, because the FAA
doesn't provide one. That is up to the airlines themselves.
Try and find where it says
'All devices must be turned off before you can shut the cabin door
and start the engines'. Try and find where it says
'everything must remain off until stopped at the jetway after
landing'. You won't find either such requirement, because
they doesn't exist.
So, there is no FAA regulation
that forces either the airlines or us to do anything. However, there is an FAA
regulation which says the airline can decide what you can and
can't do (and a different regulation requiring passengers to follow the normal
usual instructions/orders of cabin crew) - but that is a very
different thing, and you don't hear the flight attendants saying
'FAA Regulations say we can decide whatever we like about when and
if you use electronic devices, and so we've decided to make you
turn them off now', do you.
If you have spare time on a
flight, take a copy of the above FAA statement and ask the flight
attendant which FAA regulation requires you to turn off your
electronics. When they say they don't know, show them the
FAA statement and ask them where it is in that.
The Theoretical Problem of
Most modern electronics emit very small
amounts of radio energy, even if they don't have a radio
transmitter in them. Furthermore, some types of modern
electronics can be influenced if they inadvertently are bombarded
with radio energy - they may get confused and the radio signals
received can interfere with the internal signals already traveling
So therein lies the potential for
interference. You may have sometimes noticed it yourself,
perhaps when your cell phone is receiving a call, and if it is
close to something like a radio or a regular phone you might hear
some noise through the radio. That is of course an extreme
example of a device designed to transmit interfering with a device
designed to receive, but there is a theoretical potential for
devices not designed to transmit to interfere with devices not
designed to receive as well.
The Reality of Interference Problems on Planes
So, now we understand the theory behind the
concern, how valid is the concern? More to the point, are
there known problems where electronics actually really truly do
interfere with airplane electronics?
And that is where we start to move into a
very unclear area. Scientific method says that you need to
be able to repeatedly recreate an identical given outcome from an
identical set of inputs in order to have a proven causality.
We are unaware of any repeatable proven definite link between any
type of regular consumer electronics on a plane and any type of
problem with the plane.
It seems possible however that these random
glitches are becoming more common. Some 'experts' claim this
is due to an increase in portable consumer electronics being used
in the airplane cabin. An equally likely explanation is that
airplane control systems have become vastly more complicated,
themselves, and are now operated by computers rather than by
humans; by electronics rather than by cables and hydraulics.
What has happened is that from time to
time, planes will act unpredictably and do strange things for no
apparent reason. The auto-pilot might suddenly reset itself,
or switch off, or perhaps decide to push the plane's nose down and
dive towards the ground - something that is alarming at 35,000 ft
and downright deadly at 350 ft.
Greater Danger at Low Altitudes
This last point is a key point, and is the
reason why airlines are very negative about any electronics being
on during the early and final moments of a flight, while
reluctantly tolerant of them while the plane is above 10,000 ft.
Above 10,000 ft, the pilots have more time to respond to anything
nasty that happens, and so the airlines are prepared to expose
themselves to some degree of risk, but the closer to the ground,
and the slower the plane is flying, the less the margin for error.
No-one really knows what causes these
occasional semi-random glitches. And we're surely all
familiar with similar sorts of glitches in electronic items at
home - bugs in computer programs, phones and MP3 players that
sometimes have to be reset, and so on. Even, increasingly,
faults in the 'operating systems' in cars that require you to turn
the car off then on again.
Better Safe than Sorry?
In none of these other situations do we
ever consider that the problem may have been caused by the phone
in our pocket, or the Kindle in our bag. But usually, in
such other cases, the potential range of outcomes from such a
problem does not extend to an airplane possibly falling out of the
sky, killing hundreds of people in the plane and more on the
ground, so such events are seldom given much consideration or
attention. They are just accepted as part of life's
Of course, we all wish for our air travel
to be as utterly safe as is possible, and when faced with the
stark choice : 'Which would you prefer, to have your noise
cancelling headphones on, and for the plane to crash and burn; or
to take your noise cancelling headphones off and fly safely?' it
seems an easy choice to make.
So, in an abundance of caution, the
airlines have banned anything with transmitters in it from
operating at any time on a plane, and all other electronics are
banned when the plane is at low altitudes.
But, does this really make sense?
While it is true that interference with the plane's electronics
may have more severe consequences at low altitude and speed, the
electronics themselves are no more at risk in these stages of a
flight. So how is it that a plane can fly for hours at a
time with a cabin full of electronics-using passengers and with no
problems at all, but then, all of a sudden, we are told there is a
risk to the plane's operational safety at lower altitude?
How real is the risk? How great is
An Attempt to Measure the Risk
The answer to these questions can be seen
from two perspectives. The first answer is that the number
of unexplained but potentially dangerous events in passenger
planes while flying in a state with passengers allowed to use
their electronics is exceedingly low.
We'll guess there might be one unexplained
event per ten million flying hours - maybe even one event per one
hundred million flying hours. To put this into perspective,
10 million hours is the same as 1150 years, and obviously 100
million hours is therefore 11,500 years. You could spend
half your life on planes, and live to 80, and have only one chance
in between 30 and 300 of ever being on a plane with an anomalous
event, which will probably have a benign outcome anyway.
We calculate these numbers based on there
being about 18,000 passenger jets in the world, and maybe another
10,000 prop planes - assume they all fly 8 hours/day, that is
almost a quarter million flying hours a day for all passenger
planes, or 82 million flying hours a year. One hears
apocryphally of puzzling incidents maybe a couple of times a year,
And now the second part of the answer is
that these are unexplained events. No-one has been
able to demonstrate that if you take, eg, your iPad and turn it
on, the plane will immediately veer to the right. Until a
can show a clear causality between something like this with an
electronic device and a response by the plane, there is no valid
reason to believe that an unexplained event is the result of
interference from onboard electronics.
It is just as likely that it was a hardware
'event' within the plane's electronics - a leaky capacitor, a bad
solder joint, a failing memory chip, a corrupted piece of data
received along a wire - as it is an external interference.
It could even be interference from solar rays. And let's not
forget the possibility of buggy software - airplane operating
systems are comparably complex to computer operating systems; and
until such time as my Windows computer stops crashing
(figuratively) I've no confidence at all in the ability of an
airplane's operating system to also not crash (and potentially
So, on the one hand, these mysterious
glitches are very
uncommon. On the other hand, no-one knows what is causing
them, and for sure there are very many other possible causes, as
well as the possibility of interference from consumer electronics.
Other Non-Aviation Electronics Seem to have No
Here's an empirical concept as well.
Chances are you often have other electronic devices resting on the
top of your computer. In my case, I sometimes have cell or
regular phones, headsets, media players of all sorts, tablets, and
all the other gadgets that surround me in my daily life directly
on top of, or very close to, my computer.
I've never ever sensed any interference
from those to my computer, even when they are inches away.
So why would an airplane's avionics, tens of feet away, and in
shielded cages, be more at risk?
Are Airplane Avionics More Vulnerable to
What is it about airplane electronics
(avionics) that might make them more delicate, more susceptible to
interference than normal home electronics? Nothing!
In fact, avionics equipment is designed to
work without problems even though they are probably plugged into
an equipment rack with lots of other pieces of avionics all around
them. They are specially built to be resilient to
interference from other nearby avionics devices.
Okay - that's a good thing to do.
But, if this is the case, why does this resilience only extend to
the strong radio frequency (RF) leakages of nearby other high-power devices, but not
also to the massively weaker RF signals possibly picked up from
portable electronic devices way away in the passenger cabin?
If a device is shielded to reduce the
leakage of interference it transmits, the same shielding also
reduces the flow of interference from outside and into it.
It isn't as though an airplane is a
radio frequency radiation free environment to start with. A typical plane is
full to overflowing with RF energy and electronic emitting
sources, in the cockpit, in the engines and generators, in the
pumps and sensors and hydraulics, in the in-flight entertainment
systems, the thermostats and heaters, the galleys, the high
powered communication radios and radars, and so on all
the way through the plane - even to the smoke detectors in the
And how about the potential for
interference between different avionics modules? You have a
collection of different semi-independent electronic boxes, all
being plugged into racks of electronics in the plane? Surely
the devices side by side to each other are more at risk of cross
interference than they are at risk of interference from devices
tens of feet away?
Adding whatever infinitesimal extra RF
emission from your iPad to this mix is like one voice struggling
to be heard in a choir of a thousand voices.
We should also understand a thing about
distance. The plane's sensitive avionics equipment is right
next to other avionics equipment, whereas your device is maybe
even 100 ft away. This is significant.
The effect or strength or energy of the
radio emissions from most devices reduces on a cube basis.
That is, if you double the distance the two things are apart, the
signal is diminished not two fold, not 2 x 2 = four fold, but 2 x
2 x 2 = eight fold. If you increase the distance from eg one
foot to ten feet apart, then the interference is reduced 10 x 10 x
10 = 1,000 times. And from six inches to 50 ft, well, you've
reduced the effect one million times.
An Excess of Ill-Informed Caution?
So it seems plain the airlines are being
extraordinarily cautious at banning some electronics completely,
and other electronic items selectively, in a situation where there
has never been a proved link between the items restricted and
their planes' electronics, and in a situation where there are
other much more likely explanations to the occasional anomalous
event that occurs with a plane's control systems.
Rather than get to the bottom of these
occasionally mysterious events, they simply decide to
inconvenience us, their passengers, 'just in case'.
And so we've seen a series of ridiculous
Luddite like moves over the years, on the basis of 'better safe
than sorry'. I remember one time in the mid 1990s getting
into an argument with Qantas; at the time they had a blanket ban
forbidding one to use CD players at any time on their planes.
They agreed there was no reason to suspect CD players of
interfering with their planes, but said their commitment to
absolute uncompromising safety meant they refused to allow even
the tiniest of risks to be present.
Of course, CD players are no longer banned,
other than below 10,000 ft, and to suggest that a CD player might
cause problems to the plane's avionics seems as ridiculous today
as, in truth and reality, it also was 15 years ago. CD players are the same as they were
back then, and Qantas (and other airlines) have slowly come to
realize that they are safe.
There are still lots of devices that are
completely banned - for example GPS receivers and walkie talkies.
Does it Make Sense to Ban Anything on Planes
Which brings me to the final part of the
article. The underlying sense - or nonsense - of the
remaining partial bans on items, either completely, all the time,
or else selectively below 10,000 ft.
The bans are often overlooked, either on
purpose or accidentally
These bans are very 'porous' in that many
people ignore them, either deliberately or accidentally. How
many times have you forgotten to turn off your phone, or your
Bluetooth headset? And, when you have your Kindle or other
eBook reader on, how many times has its Wi-Fi transceiver been
active? Or even the Wi-Fi transceiver in your laptop?
Chances are you never think to turn that off, even though the
airlines ban any type of radio transmitter at any time.
There are also stories of people on planes
who, after being instructed in the strictest possible terms to
have all their electronics turned off, have then been listening to
the pilot's announcement only to hear a phone start ringing in the
background in the cockpit. This is not just urban legend -
I've had pilots tell me it has happened to them personally.
Some electronics are not banned
Indeed, why are we allowed to leave hearing
aids on? Why are we allowed to leave our digital watches on?
Or pacemakers and oxygen flow enhancers?
How is it that a digital watch is 'safe',
but a digital eBook reader is 'dangerous'? How is it that a
hearing aid is 'safe' but noise cancelling headphones are
Why is the inflight entertainment system
'safe' but your personal video player 'dangerous'?
Why do we have to turn off 'anything with a
power switch' but the airline doesn't have to turn everything of
its own, on its plane, off too?
Not all airlines ban the same things
These days the airlines don't all uniformly
have complete blanket bans on radio transmitters any more.
Many airlines now allow cell phones to be used in flight.
So they are willingly exposing their planes
to the most 'scary/dangerous' of all electronic items - high
powered digitally transmitting multi-frequency cell phones, that
may be squirting out signals on half a dozen different frequencies
simultaneously. And many phones these days have built in GPS
receivers too - another item otherwise completely banned.
So how is it that some planes, operated by
some airlines, can safely allow some electronic items to be
operated, whereas other airlines - flying the exact same planes -
claim them to be too dangerous to ever be turned on?
Why do some airlines allow you to turn your
cell phone on as soon as the plane has touched down, whereas
others require you to wait until the plane has stopped at the
Looking at the Problem from the
The problem, such as it is, is
that on rare occasions, the electronics in a modern airplane will
suddenly act unexpectedly.
We don't know what causes
these unexpected and non-duplicable events to occur. There
are many possible explanations, ranging from bugs in the software
that controls the equipment through to faulty components in the
The airlines have decided to
share the blame generously with the portable electronics that we
travel with, even though they have no certain scientific proof
that our electronics might be causing these problems.
This lack of proof is understandable,
because it is close to impossible to recreate these 'glitches' at
But - flip this last statement
around. Let's not focus on trying to prove that our
electronics cause problems. Let's instead prove they don't.
Surround any part of a plane
that has given problems with a mix of all the typical electronic
devices, all operating simultaneously, and see if the plane part
functions normally or not.
If it does, then surely it is
reasonable to infer that whatever the cause of its rare glitches,
it is not anything to do with consumer electronics.
This doesn't tell us what
causes the problem. But it does tell us what doesn't cause
the problem, and surely that is significant and valuable.
There is another explanation
for the possible increase in unexplained glitches. Maybe
these events are not due to the increase of consumer electronic
devices on planes. Rather they may be due to the changing nature
of airplane control systems. What used to be operated by
wires and pulleys have become computer controlled systems, with
increasingly complex and sophisticated computers controlling them.
Could the problems be due to
the airplane's own control computers, rather than due to your
iPod? Could they?
What do you think?
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13 May 2011, last update
28 Nov 2012
You may freely reproduce or distribute this article for noncommercial purposes as long as you give credit to me as original writer.