The unknown factor is how long we have before climate change bites. It may well be that the situation described by James Lovelock in 'The Vanishing Face of Gaia' eventuates before we run out of fossil fuels, in which case its highly unlikely that any of the major airlines will be in business anyway.

kadaitcha;
We will never actually run out of fossil fuels, it is just
that when production falls they will become too expensive to be used
like we do now. The further production falls the more expensive they
will become.
It is this rise in price that will do the airlines in.
It will be too expensive to casually fly off on a holiday or to visit
your parents. Business will find video conferencing a better deal.

If instead of a gradual increase, we get what happened in 2008 then
the airlines will collapse over a very short time.
It is no exaggeration to say that the airlines are the canary in the mine.

In the first half of 2008 24 IARTA airlines went into bankruptcy.
Swiss Air has gone, Alitalia is on drip feed. Sabena is now bankrupt.
This year JAL is now bankrupt and British Airways in in deep
financial trouble. Even Qantas is looking for a partner, hence the
change in ownership rules.

It remains to be seen how much governments will finance loss making
airlines.

I foresee the return of intercontinental travel by sea.

What timeframe applies to fossil fuels becoming economically unviable ?? Judging from the frantic scramble by virtually all car manufacturers to get battery electric cars into production its probably much closer than the sheeple realize. As you state, the backlash will certainly affect aircraft unless alternative fuels can be found. Whilst ethanol can potentially do the job for both piston & turbine engines, the viability of using increasingly scarce farmland is certainly an issue. Whatever, the wild card is just how quickly climate change will change civilization as we know it. Australia can't grow sufficient food for its existing population so if / when international suppliers are affected then it will unquestionably place more strain on our ability to survive. Ultimately the mass starvation due to inadequate food supplies will reduce populations to maybe a quarter of what we have now, but thats another can of worms.

kadaitcha,
>What timeframe applies to fossil fuels becoming economically unviable ?

Well about now !
May 2005 crude oil production peaked.
July 2008 crude oil plus all liquids peaked.
The above seems to be the consensus of significant experts.
Re bio fuels for aviation. I can't remember which fuel it was but the
temperature at altitude caused it to thicken or solidify.
This whole business seems to be full of catch 22s.

The effects of peak oil will occur much sooner than global warming.
Indeed the current financial crisis was caused by peak oil forcing
the collapse of the housing loans in the US.
Have a read of this, it is long but does cover the whole problem well.

http://www.postcarbon.org/article/40503-temporary-recession-or-the-end-of
Here is a tiny url
http://tinyurl.com/ybnhxzk

Australia produces about half of what we use, ie about 450,000 Bpd,
Our production peaked in 2000. China has had an increase year on year
of 17% and India an increase of 8% yoy.
So it is not unreasonable to expect a scramble for supply.
The IEA says a bit tight this year, so it will be interesting to watch
prices. I have a graph with the ASX, Oil price & oil production.
It is interesting to see how they track each other.
The ASX goes up with other indices indicating a recovery and the oil
price goes up with it. So I am watching the oil price and if it goes
up steeply, it will be time to jump.

kadaitcha,
I have just watched an interview on BBC World with two economic experts
from Standard Charters and UBS banks.
They are quite convinced that there will be good growth in the coming
years. Listening to them I am amazed that they can sit there and show
such ignorance.

I have noticed on TV plenty of financial experts telling us how
recovery will go on indefinitely. They talk about the present recession
just as though it is just another recession and it will soon be
business as usual.

Have a read of that link I sent you and you will see that it just
will not be possible.

The discussion to date seems to assume that technology isn't going to advance by much. However, if the claimed potential for the production of fuel from algae is actually realized then we may still be flying to holidays in 2050.