Transport Insights

A baffling announcement from the transport secretary has shone a light on her department’s determination to make the facts (or predictions) around carbon emissions fit Labour’s policy of expanding aviation in a climate emergency.

A written statement to parliament from Heidi Alexander begins:

On 19 February I wrote to the judge hearing the above claim in respect of my ongoing duty of candour in those proceedings.

There is no reference before this, or indeed anywhere in the statement, to any claim or proceedings, although Alexander does later make equally baffling references to:

an order of the court from 10 December 2025

and to having

apologised to the court and the parties and submitted a statement from a senior official in the department to explain the error and correct our position.

At no point does she say which court but, unpicking all this, it looks as if the case is the legal challenge to Alexander’s decision to back expansion of Heathrow. You can tell this because she protests that

The information contained in the disclosed documents was not relevant to my original decision to grant a development consent order for the expansion of Gatwick Airport.

Alexander explains how what she describes as “a small error” came about:

During the process of updating the department’s aviation model in preparation for the development of new forecasts to support the setting of carbon budget 7, and the quality assurance processes involved in this, officials in the department identified that the disclosed data contained a small error.

The error came from the incorrect application of fuel efficiency measures (and therefore incorrect emissions values) to next generation planes that were modelled as flying beyond their standard operating range. This meant that in the small number of cases where an aircraft is modelled as flying beyond its optimal range, its emissions values were wrong.

As a result of this correction, the headline difference between the average annual total aviation emission figures as provided to the court and the corrected figures for the CB6 period is an increase of 4.1 MtCO2e over the 5-year carbon budget 6 period – i.e. with an annual average difference of 0.8 MtCO2e.

So, just to be clear, the DfT has again claimed that planes that don’t exist will be able to do things that they won’t be able to do and “accidentally” underestimated their impact on the climate.

If officials were doing this in good faith, rather than in pursuit of a builders not blockers” policy under which, as Keir Starmer said:

we can have the expansion of the growth that we need at the same time as meeting our climate obligations

you could accept that it was a small error.

But, in the circumstances, it looks like fiddling the figures.