The person saying it can't be done
is liable to be interrupted
by the person doing it.
Multitasking -- aka division of attention -- can be done. I get paid
to do it. I get paid to teach other people how to do it.
Here's a /simplified/ description of one scenario: You are flying
the "downwind" leg of the airport traffic pattern. http://www.cfidarren.com/r-approachland2.jpg
You are looking out the window so as to see and avoid other traffic.
Note that nearby traffic is plentiful, hard to see, and rapidly moving.
You are also looking out the window so as to perceive pitch attitude,
bank attitude, heading, position, crosswind correction angle, and
other variables. You are also looking at the instruments so as to
quantify the airspeed, altitude, engine power settings, et cetera.
You are manipulating the primary flight controls. You are also
changing the configuration of the landing gear, flaps, elevator
trim, mixture, and possibly other things. You are talking on the
radio. Also, you are listening attentively to the radio, interpreting
what you hear so as to form a three or four dimensional model of what
other people are doing. Et cetera.
If you tell me you can do all that automatically, with little or no
cognitive workload, then congratulations, you must be the world's best
pilot. Either that or you have no idea what you're talking about.
As for the difference between talking and texting: In sufficiently
fancy aircraft, text messages can be sent to and from the cockpit. http://en.wikipedia.org/wiki/ACARS
The feature has been around since circa 1980 ... long before personal
phones that could send SMS were widely available.
Even more to the point, in non-fancy aircraft, there is a lot of
paperwork in the cockpit, including navigation charts, flight plans
(which also serve as progress logs), checklists, et cetera. Using a
GPS reduces the amount of paper but /increases/ the cognitive workload,
because the GPS user interface is several sandwiches short of a picnic.
This is relevant because updating the flight plan (on paper or in the
GPS) involves the eyes and the hands and nontrivial cognitive workload.
It's like texting, only more complicated. You have to do this while
flying the airplane. Division of attention is required. It's not like
driving a car, where you can pull to the side of the road for a few
minutes if you want to look at maps or do some texting.
This is the relevant difference between piloting and driving:
-- In the airplane, you have no choice. Division of attention on a
grand scale is necessary, so you simply must learn to do it properly.
-- In the car, you have a choice. Simply not allowing drivers to
make phone calls is an option, and I suppose it is simpler than
teaching them how to do it properly.
That's the relevant difference. Please don't tell me you think it's
OK for pilots to talk on the radio mainly because the cognitive effort
is so much lower (allegedly, compared to phoning while driving).
The idea that the cognitive content of the conversation is the dominant
risk factor is a non-starter for another reason also, as should be obvious
from the fact that even in jurisdictions that forbid talking on the phone
while driving, they allow talking to a passenger in the car ... which
involves the same cognitive content.
===========
With division of attention, as with anything else, there is a right way
and a wrong way to do it.
Learning to properly _allocate_ your attention is part of the training.
Suppose you taking the final practical test to become a private pilot.
I pretty much guarantee that during the checkride, in some inopportune
high-workload situation, the examiner will drop his pencil to the floor
and ask you to fish it up for him ... in which case the only appropriate
response is "Stand by." That's pilot-speak for "Let's worry about that
later."
Let's be clear: You are not supposed to look for the pencil, let
alone reach for it. That would be improper division of attention,
and it would be grounds for flunking the checkride.
That's a contrived situation, but analogous non-contrived situations come
up all the time. Suppose you are on short final, trying to land the plane
in a gusty crosswind. On the radio, you hear the tower controller asking
you a question. The only correct reaction is to ignore the question.
Common courtesy says you should answer the guy, but safety is more important.
Get the thing landed and stopped, then chat with the controller. You won't
even get the chance to apologize for not answering earlier, because by that
point the controller will have figured out what just happened, and will be
apologizing to you, apologizing for the distraction.
========================================
Last but not least, there is an important connection between multitasking
and ordinary terrestrial grade-school teaching and learning.
I know at least a dozen people who hold research jobs, with very high pay
and very high responsibility, who during childhood were diagnosed as being
"mentally deficient" ... presumably because they would not pay attention
in class.
It's not like they couldn't pay attention ... it was just that they wouldn't
pay attention, and there's no good reason why they should have paid attention,
because they were bored to tears.
A generation ago, the school would have just skipped such a kid ahead a
grade or two, but that has cons as well as pros ... and in any case, it
seems to be strongly out of fashion now, at least in the public schools.
(And people wonder why there is a such a rush to charter schools.....)
I tell such kids: Plan A should be to escape from that situation. School
is not supposed to be like going to jail for six hours a day. It's supposed
to be interesting. Failing that, Plan B is to learn to "fit in" by learning
to multi-task. That is, learn to devote 1% of your attention to the class
while devoting the other 99% to something else. For example: Sit in the
back of the class and read a library book, or draw something, or calculate
something, or compose something ... but keep one ear open enough so that
if you get called on you don't need to ask for the question to be repeated.
Unless the teachers are exceptionally clueless they will know what you're
doing, but if you play the game properly you can get away with it. As long
as you pay a little bit of attention they don't care what you do with the
other 99% of your brain. Plan B is not so bad. You sit in school for a
few years and read a few hundred books. Eventually an owl brings you a
letter and you get to go someplace where they actually do interesting things.