Further to Rob's post re fuel costs........

"Wine may get better with age, but airplanes don't. And that's a
problem for US carriers, which operate some of the oldest fleets in
the world. Younger planes are more fuel efficient, which puts US-based
airlines at a huge disadvantage when compared with foreign
competitors.

There's no getting around the fact that the the fleets of US airlines
are on the old side. On average, American Airlines' planes have seen
15 years in the sky, United's 14, and Northwest's 11. Post 9/11, US
airlines had their hands full just trying to stay in business, but
when they finally emerged from that downturn, they called in orders
for hundreds of new jets. Continental and Northwest lined up for
Boeing's sleek and green new 787. US Airways shopped for shiny new
Airbus widebodies to fuel its international expansion, and American
was said to be mulling a replacement for it's rapidly aging MD80
single aisle fleet.

But high fuel prices and the resulting capacity cuts have put many of
these plans into question. JetBlue and Airtran have deferred delivery
of new planes, and an Airbus executive admitted that the company is
expecting more. When an airline like American cuts its schedule by
over 10 percent and and sends 85 planes to that big parking lot in the
sky, you've got to think that fleet renewal falls off the top of its
to-do list.

In the meantime, foreign airlines are ordering up a storm. Air France
is waiting on 14 A380 superjumbos, 18 777s, and 20 A320s, while
Dubai-based Emirates has a stunning 242 planes on order. Aircraft
renewal yields younger fleets: Air France's planes have an average age
of 8.8 years, and Emirates' a downright youthful 6.2 years old.

Is this really such a big deal? Absolutely. The Department of
Transportation estimates that the Boeing 767, a plane that began
service in 1982, burns an average of $17.85 per passenger per hour,
while a newer A330 burns $15.72. The newer the fleet, the lower the
fuel bill. The lower the fuel bill, the lower the total cost of
operations.

One myth that needs to be debunked, though, is that aging planes are
less safe. Even with its older fleets and recent high-profile events
like the grounding of American's MD80s, the US industry has an
excellent safety record.

But even that comes with a price. Because their planes are older, US
airlines often find themselves spending more on parts and
maintenance." Source Wired.com blog

As somebody said - it's a bit of a worry when your aircraft armrest
has an ashtray.