Freesteel Blog » 2018 » December

Saturday, December 15th, 2018 at 1:57 pm - - Whipping

In March 2018 Liverpool John Lennon Airport published its Masterplan 2050 to justify their “need for expansion”. It was based on a single extremely cherry-picked datapoint from an out-of-date government forecast.

The plan included this suspiciously simple forecast chart on page 29:

Page 23 of their “Master Plan” states:

Department for Transport UK Aviation Forecasts

[Paragraph 1]: The Department for Transport (DfT) 2013 forecasts for aviation were produced to inform long-term strategic aviation policy at that time, including the Government’s Aviation Policy Framework. The document set out forecasts for air passengers, aircraft movements and CO2 emissions at UK airports. The key findings include the following:

  • demand for air travel was forecast to increase within the range of 1% – 3% a year up to 2050; and
  • the central forecast was for passenger numbers at UK airports to increase from 219 million in 2011 to 315 million in 2030 and 445 million by 2050. This is an increase of 225 million passengers over the next 40 years.

[Paragraph 2]: The DfT central forecast from 2013 projected passenger traffic at LJLA at 5.3-6.7 million ppa by 2030 growing to 6.8-15.4 million ppa by 2050. This Master Plan includes proposals to enhance services and meet the levels of passenger traffic envisaged within these national forecasts. Forecasts are presented as ranges to reflect the inherent uncertainty in forecasting over relatively long periods. LJLA has undertaken its own detailed forecasts based on its knowledge of the market and trends in aviation and utilising the DfTs long term growth rates for the UK. These forecasts have been peer reviewed by York Aviation and form the basis of the Master Plan proposals.

[Paragraph 3]: In October 2017, the DfT issued a revised set of aviation forecasts with the primary purpose of informing longer term strategic policy, rather than providing detailed forecasts at individual airports. These forecasts superseded the 2013 forecasts; however the longer term growth rates for airports outside of London continued to be within the 1% to 3% range as in the 2013 forecasts. Given that there is minimal change in long term growth rate, and the recognition by the DfT that forecasts at individual airports will differ from their own, there is no change to the forecasts utilised within the Master Plan.

In spite of a lack of clear references, we can identify the source as the UK Aviation Forecasts 2013 [withdrawn on 24 October 2017] from the Department for Transport, because Paragraph 1 lifts two sentences from it:

Then Paragraph 2 provides the numbers:

  • 5.3-6.7 million ppa by 2030
  • 6.8-15.4 million ppa by 2050

These four numbers come from the table (subject to a typo) on page 159:

Note that because the National Air Passenger Allocation Model (NAPALM) is a bit unstable, the values for the high end simulation possibly blew up and gave passenger projections greater than the actual population of the UK, which the DfT decided not to publish.

There’s a chance that the central range projection is also subject to this problem, with numbers that have a tendency to spike up when they hit a certain date. Experts at economic modelling are supposed be able to recognize this phenomenon and refrain from publishing garbage.

Those four data points are not much to base a graph on.

Luckily, pages 154 and 158 of the same document fill in the values for 2020 and 2040 to get a fuller picture of the curves:

We can take this complete set of numbers and graph them against the Liverpool Airport projection:

Clearly, all they did was pick a halfway number at 2050 — which they liked — and drew a straight line to it, ignoring the fact that this line went far out of bounds until at least 2043.

But what of the claim in Paragraph 3, where they write:

“In October 2017, the DfT issued a revised set of aviation forecasts with the primary purpose of informing longer term strategic policy… Given that there is minimal change… there is no change to the forecasts utilised within the Master Plan.”

The Department for Transport must be pretty disappointed, because Liverpool Airport is not at all interested in informing its long term strategic policy.

Evidently, they decided they didn’t need to download the spreadsheet provided with the
UK aviation forecasts 2017 or plot its complete table of projections. If they had done, it would have looked like this:

Thus we have conclusively established the sources of all the passenger projection numbers used by Liverpool Airport in their so-called Masterplan, and proven how they have cherry-picked a single out-of-context number from a DfT forecast from 6 years ago, drawn a straight line to it, and then lied about the relevance of the most recent DfT forecast numbers.

This level of mendacity ought to discredit everything they say about the matter, and should mean their plans for expansion into the surrounding green belt land is rejected by the Authorities, as there is no basis to believe their claim that it will create more jobs or have any other benefits.

People should print out and take copies of the graph above to show to politicians at meetings claim to be able to read graphs.

Update: For bonus points, here is the diagram from page 20 of the Discussion paper on aviation demand forecasting from the Airports Commission in 2013 showing the points in time when they predict the various airports would reach their capacity, where they put Liverpool joint last on the list: