I'm planning to take a long overseas trip and have scored a business
class seat, and so will have a power source at my seat.  (Or so they
tell me.)  However, I can't figure out what I'll need to plug in.  All
info from United seems to point to buying a new transformer, but
logically, I think I only need a cord that goes from my (IBM Thinkpad)
brick to whatever shaped power outlet is on the plane.  I don't need
this for any other reason (auto, etc), and I can plug my Treo into the
USB on the laptop, so I'm really just looking for what I think is a
cord with the right end bits.  Is there a simple solution that I'm
missing?

treewishes-ga:

Thank you for your question, I hope that you find the information below useful.

The major American carriers have standardized on a power outlet
referred to as an Empower outlet for their First and Business class
seats. You mentioned United Airlines, so I presume that this is the
carrier you are using for this overseas trip. Let's start with the
United website and the information they provide there about their
onboard power:

http://www.united.com/page/article/0,6722,1074,00.html

The adapter that they are recommending is the iGo Juice70, considered
by some as the best all-around travel power adapter for laptops due to
its ability to be used on airplanes, in cars (cigarette lighter
adapter) and in foreign countries due to its universal transformer.
Essentially, it can take just about any available power and convert
and condition it to the specific requirements of your laptop. The
United referral link is:

http://www.igounited.com

and the direct company link is

http://www.igo.com

As you'll undoubtedly see from the iGo website, the Juise70 is not
cheap. Unless you are a frequent business-class flyer, it's hard to
justify the MSRP $119.99 US. Unfortunately, it isn't as simple as
getting a basic cord to plug between the Empower outlet and your
laptop's DC jack, though. The Empower outlet, like a car cigarette
lighter socket, is nominally 12 VDC. This is subject to variation and
surges. Your laptop requires anywhere from 14.4 to 20 VDC regulated,
with the very real possibility of damage if the input voltage surges
or spikes. So, you need some sort of adapter device in between to
clean up the power from the Empower socket, convert it to the
appropriate voltage for your PC, and keep a steady supply of clean
power flowing.

There are many options for airplane power adapters out there. Froogle
helps us find the following:

http://froogle.google.com/froogle?num=50&hl=en&lr=&newwindow=1&c2coff=1&safe=off&tab=wf&q=airplane+adapter+laptop&tiled=1&scoring=p

and from Nextag:

http://www.nextag.com/serv/main/buyer/outpdir.jsp?nxtg=8db8a_625BE135A91C834F&search=laptop+airplane+adapter


You'll see that there are options ranging from plug adapters that
would let you convert the Empower outlet to a cigarette lighter
socket-type outlet (in case you already have a power adapter for use
in your car), to full systems that are similar to the iGo Juice but
cheaper (remembering that you get what you pay for). If you aren't
going to be travelling much, then you may want to consider just
getting a power inverter, that you would use along with your existing
AC power adapter. These units take up a bit more room, but are
versatile enough to let you use them to power other low-wattage
devices like your cell-phone or PDA charger in your car, for example.
Here is one example:

http://www.cyberpowersystems.com/acmobile140CHI.htm

You will need to consult your laptop's manual to see exactly how much
power (in Watts) is required by your AC adapter; most laptops are OK
with the 140W version, which can be found at online retailers such as:

BestBuy
http://www.bestbuy.com/site/olspage.jsp?id=1075583463235&skuId=6321713&productCategoryId=cat08005&type=product

Remember though, that like many of the other passenger conveniences on
board an airplane these days, there really is no guarantee that the
Empower outlet will actually be working in your seat, so be prepared
to do some negotiating on board the aircraft after take-off if you end
up having bad luck with the outlets near you; you may need to convince
someone to switch seats with you.

Have a good flight!

aht-ga
Google Answers Researcher

Very complete answer, and good advice.  The comments were also
interesting -- one confirmed the answer, and the other was blatant
spam.  Is this standard for GA?

Somehow I suspect you need a transformer.

I know one airline (Boeing fleet) that rents them out from the Duty Free trolley.

Personally I would follow AHT-GA's sound advice and get a really pukka transformer.
Frying your Thinkpad is an expensive risk.

Also I would consider the following tips given to me by a very
experienced long haul traveller (and they work).
1) Dress smart and be really nice with the check in staff - ditto with O/B crew
   (you might get an upgrade to F/C)
   Look athletic and competent, the seats by the emergency exits are B/C++
2) Just after the meal service, nip out to the loo and change into a track suit
3) Take a few Temazepan 10mg tablets (short acting valium) and sleep for 8 hours
4) Get changed back into smart gear (fresh shirt etc) and shave.

If you must use your laptop - turn the sound off before you leave home.
Also - rip the battery out of your mobile in the departure lounge.

Major tip - get two really good books.

Bon voyage

I raised a similar question to our mainteneance staff while enroute
from Los Angeles to Sydney yesterday. I am the pilot of a 747 for a
major airline. Respones I received from them (our London Maintenance
base) indicate that there are Units called In Seat Power supplies
"ISPS" in each pair of seats. These are used to rectify the power
(convert it from AC to DC) and also stabilise the power to the outlet,
as well as providing circuit protection, overcurrent, and thermal
protection.

In examining the outlet, I noticed that it is placarded as 16 VDC. I
have a Sony Vaio that uses, coincidentally, 16 VDC. My question to
them was the same as that above - can I make a cable to go directly to
my laptop? I know that the "adapters" they sell you are capable of
converting house current and automotive power to laptop-compatible
current. They have transformers (to change voltage) and rectifiers (to
change AC to DC). This is the same function provided by that
inconvenient box you plug into the wall when you plug in your laptop.

It seems nobody is sure about anything. The maintenance people told me
to let them know if it works (inspires confidence, no?). I iintend to
take a multi-meter with me on my next trip and start testing the pins
in one of those outlets (assuming the TSA will let me take a meter
through security - many things they do don't seem to make sense).

My feeling is that if your laptop matches the plug voltage, it should
work just fine. But don't quote me either.

Good luck.

skyken,

You have confirmed my suspicions! 

I ended up buying the iGo Juice, mostly because I actually would like
a second power supply... and also to try it out enroute.  Seems like a
good product, actually.

But as for using it in the air === Coincidentally... or not... the
power at my seat for both the outbound and inbound flight was out of
order.  The crew didn't seem particularly surprised or concerned. 
They implied that other seats worked, but I didn't want to bug someone
else to check.  On the outbound, it was apparently just my seat; on
the inbound, it was the entire left side.

So I dunno.  Hope your research goes well!