Our challenge is that the proposition we have from the Airports Commission of one additional runway at Heathrow airport will not deliver what everyone is rightly calling for, said Rod MacDonald.

This week at the Runways UK event we heard several eloquent and powerful speeches stressing the importance of more air-transport capacity to enable us to continue to be the great trading nation that we are. 

These speeches culminated at supper in a very persuasive speech from Lord Digby Jones.  All that was said was much in line with the London First ‘Let Britain Fly’ campaign and anyone in the UK who is involved in international business knows that this campaign and the sentiment of these speeches is right and of vital importance to the future of the UK.

"But with the 3 runways at 80% occupancy (the norm accepted for timetable resilience) we would get only 4.54 hours more runway time compared to what we have at present." 

Our challenge is that the proposition we have from the Airports Commission of one additional runway at Heathrow airport will not deliver what everyone is rightly calling for.

Why do I say this?  (For the numerical detail, see my arithmetic below.)

But with the 3 runways at 80% occupancy (the norm accepted for timetable resilience) we would get only 4.54 hours more runway time compared to what we have at present. 

Even at 90% occupancy we would get only 9.64 additional hours. 

This increase would not be delivered for 10 to 12 years and we have no other plans for the future.  The Commissioner is clear that a 4th runway at Heathrow would not be acceptable.

"Let us not be a burden on our children and their children by instigating yet another Great British Fudge."

The Commission was asked to look at the challenge in the long term. Sadly it did not. I am not alone in believing that we need a 24 hour/day 4-runway airport; somewhere, anywhere that such a megalith is acceptable and can be linked to excellent ground transport. 

As Mark Carne said this week at the ‘Tomorrow’s Rail’ event, “we need to get the engineering right before we make our big decisions”. 

Let us not be a burden on our children and their children by instigating yet another Great British Fudge. We need to put a lot of effort into getting any decision from our politicians. Let's put our efforts into getting the right decision. 

Rod Macdonal is former senior partner at Buro Happold and past chairman of the ACE

The arithmetic. 

Currently Heathrow has 2 runways operating from 04:30 to 23:00 or 18.5 hours each day. We are told that the runways operate at 98% capacity. That suggests 18.13 hours each day or 36.26 hours total on 2 runways. 

The Commission proposal is for a night ban with no flights before 06:00.  That is a reduction each day to 17 hours. On 3 runways that is 51 hours.  It is well known that to operate runways without unacceptable delays they should be run at about 80% maximum capacity. 

This would mean a total of 40.8 hours on the 3 runways, or 4.54 hours more than on the current 2 runways. 

This is clearly not going to work so say the runways are operated at 90% occupancy giving 45.9 hours total this would give 9.64 hours more capacity or 26.5% more capacity compared to the present operation.