I am flying to Japan on an Air France flight soon (May 20th).
My wife and I will be accompanied by our 13 month old daughter.
We understood we could take a car seat on board for her, so we booked
an extra seat.
The airline have now told me that the maximum width of the seat must
be 41cm.
Our seat is 47cm, and narrower seats seem hard to come by. I would
like information on car seats which comply with this width
restriction, plus stockists, who will need to be based in the UK (or
have UK outlets).
I have done quite a bit of searching already, and haven't found any
concrete information on the subject (I've tried Google, and Google
Groups). I've found a lot of products claiming to be FAA approved, but
I suspect they may all be too wide for Air France. Very few come with
detailed measurements.

I was unable to find a car seat to buy online with width
specifications of 41cm or less. But, I have found some great resources
to help with your search.
 
Here is a list of baby product companies based in the UK with product
helpline numbers. They should have exact measurements for car safety
seats they manufacture.

http://www.argos.co.uk/webapp/commerce/command/ExecMacro/displaystatic.d2w/report?page=help&order_rn=

A list of UK based retailers with phone numbers and web sites.
http://www.preciouslittleone.com/uk/links/pushchairs.asp

I have also found the following companies who are UK based and sell
car seats, but do not list exact measurements online. Their web sites,
names and numbers are listed below:

Littlewoods Extra on 0845 757 3457
http://www.littlewoodsextra.com/extra/rf.inf.SessionServlet?pathinfo=extra/browse/Thumbnails.html&rootcat_id=18652792&version_id=64

Marshall Ward 08701 51 52 53 
http://www.marshallward.co.uk/mward/category.asp?brand=MWard&cat%5Fid=3014&zone%5Fid=&page=2&orderby=4&offer%5Fid=Z&extra=&mscs_sid=KBBQALNEUN159KTGHH9HCFKK1CRABLUC

Discount Baby Store  01834 813170
http://www.discountbabystore.co.uk/index2.html

Britax Worldwide +44 (0) 1264 386034 
http://www.britax.co.uk/main1.htm

I hope this contact information puts you in touch with a company that
sells a car seat to fit your needs.

Thank you!

You may be able to find a seat at www.babiesrus.co.uk or
www.babiesrus.com

If your child is over 30 pounds, they could use the Star Riser Booster
Carseat, it is only 15.5 inches wide, which I beleive converts to
39.37cm. This product is available from babies-r-us.

Hope this helps.