Domestic Flights Fuel Duty

On Left Foot Forward is a post recommending that domestic air travellers subsidise rail travellers. In the article, the author claims:

If the tax was introduced at the same rate as motoring fuel tax, it would raise around £460 million a year – enough to make up for revenue lost by cutting rather than increasing train fares.

I'd like to know how that figure was reached.

According to CAA statistics (Table 0 1 7 4) there were 7.7 billion seat-km of domestic flights in 2010. According to this site planes uses between 0.035 and 0.05 litres per seat-km, a range confirmed in this wikipedia article. That gives a range of between 270m and 385m litres of fuel used in 2010. The current fuel duty rate is 58.95p per litres.

Thus a duty on aviation fuel would generate between £160m and £227m. That's between 35% and 50% of the claimed amount.