The Liberal Democrats say they would put an extra £10 tax per ticket on internal flights in Britain to help fund improvements to the rail network.
Funds would be used to improve rail services, Lib Dems say
They are also proposing to put a toll on road freight, while encouraging private investment in railways.
The party says it would generate £12bn in five years and be a temporary measure, without specifying how long.
The proposals are part of a package aimed at making Britain's transport system carbon neutral by 2050.
The Lib Dems will discuss the proposals at their annual conference in September.
So-called "lifeline" air routes, such as links between the Orkneys and Shetland and the mainland where travel options are limited, would not be taxed.
The flight charge would generate £150m a year, and the freight toll could raise £600m annually to be put in a "Future Transport Fund".
Lib Dem environment spokesman Chris Huhne said the flight tax would curb the growth in the internal flights and shift freight from road to rail, potentially cutting the UK's carbon emissions by more than 2.6 million tonnes a year.
Private motorists would be spared in the near future, however, with Mr Huhne saying that a national road pricing scheme was not a practical option within the 10-year period in which experts say action must be taken to halt global warming.
Other environmental measures include higher taxes on gas-guzzling cars and a change in air duties to levy charges on flights rather than individual passengers.
Mr Huhne said the air market in France and Germany had been "killed" when high-speed rail alternatives were introduced, and he hoped the tax would prevent the expected growth in UK domestic flights.
The freight tax would follow similar schemes used in Germany, Austria, Switzerland and the Czech Republic, with truckers paying on average 11p a mile, although the charge depends on vehicle emissions.
Mr Huhne said: "Plans to improve the railways must not be scuppered yet again by public spending constraints.
"The Future Transport Fund will provide ring-fenced funding for the improvements that future generations need if we are to cut our carbon emissions."
The fund would be used for high-speed rail links connecting London with Birmingham, Leeds, Manchester, Tyneside and Scotland in the north and Bristol, Cardiff and Exeter in the west.
It would be used to cut passenger fares; remove bottlenecks in the system at locations like Reading and Swindon; contribute to relief schemes like London's Crossrail; increase train lengths; and reopen some closed lines, such as the Oxford-Cambridge link.
Transport Secretary Ruth Kelly recently announced that £10bn would be invested by 2014 to increase rail services and lengthen trains.