Fifty proposals have been put forward to the government’s airports commission to safeguard the UK’s international aviation hub status.

About half make the case for additional runways, including Heathrow’s proposal for a third runway.

The panel received proposals that the level of Air Passenger Duty should be cut, but there were also proposals for APD to go up.

Commission chairman Sir Howard Davies (pictured) said that a few ideas were a “little far-fetched” but said there were some interesting new proposals.

He said: “There are a number of interesting new proposals. For example, Heathrow are proposing something which is rather different from what was planned before, so the old third runway is not in fact now on the table, but other different types of runway are.”

Sir Howard told the BBC: “It’s very important that what we propose is within the climate change policies that are legislated, of course.

“So some of the ideas that we just expand to cater for any level of demand, I think, are implausible because you cannot imagine aviation growing so much that the climate emissions of the rest of the economy have to be reduced to zero in order to accommodate it.

“So we are looking at that first, and we are then looking at what use you can make of other non-London and the southeast airports, and only when we have done that will we see just what additional capacity is required in London and the southeast. All of that will be done by December.”

The commission will whittle down the 50 proposals to a short-list of the “most credible long term options” by the end of the year before analysing further.

There will be further opportunities to comment and submit views on the shortlisted options in 2014 followed by a full report in 2015.