Air travel: A normal good?

http://news.bbc.co.uk/1/hi/business/7945721.stm

a) What evidence is ther to suggest air travel is a normal good
b) If this is the case, would the income elasticity of demand for air travel be +ve or -ve? Explain your answer
c) The following passage lists has many statistics: What use would they be for firms planning their stratagy to deal with the downturn in passenger numbers?

UK airports handled 235 million passengers in total last year, the CAA found. The 1.9 per cent decline is only the the fourth annual decrease in passenger numbers since the end of the Second World War, the authority said.

CAA figures revealed London's airports, including Heathrow, Gatwick, Stansted, Luton and London City, saw an overall annual fall of 2%. Stansted was particularly badly hit, with 1.4 million fewer passengers in 2008 - a 6.0% decline on 2007.
Manchester, the biggest regional airport, also saw passenger numbers fall by 3.8%.

However, not all airports were hit by a decline in travellers. London City airport saw a rise of a 12%, Luton showed a 2.6% increase and Birmingham's numbers rose by 4.8%.

Rail competition

The CAA also revealed charter airline numbers were down 9.3% on 2007, while scheduled airlines were down 0.8%. There was also a fall in the overall number of passengers taking domestic flights - down 4.8% to 25 million.

The authority said this was partly due to increasing numbers of people opting to take the train.