There has been a lot of discussion again across a number of threads about how CWL can increase its passenger throughput. CWL does well in summer particularly with holiday routes and it's some of these that are likely to be the ones to boost passenger numbers in the foreseeable future.
Some people have also pointed out, and this has long been a known situation, that CWL would benefit if it could raise its winter profile.
I've taken the CAA annual and monthly stats for terminal passengers at both CWL and BRS for 2018 (to the nearest thousand), with CWL also shown as a percentage of BRS's numbers each month and also for the year. BRS figures are shown in the left-hand column then CWL's and finally that percentage.
Annual 8,697,000 1,579,000 18.2%
Jan 486,000 70,000 14.4%
Feb 517,000 78,000 15.1%
Mar 555,000 96,000 17.3%
Apr 703,000 105,000 14.9%
May 834,000 165,000 19.8%
Jun 908,000 181,000 19.9%
Jul 938,000 192,000 20.5%
Aug 965,000 202,000 20.9%
Sep 889,000 178,000 20.0%
Oct 802,000 140,000 17.5%
Nov 529,000 85,000 16.1%
Dec 571,000 86,000 15.1%
The above shows CWL's perhaps over-reliance on the May-September period. Both airports' best and worst months were the same - August and January, and this is usually the case most years. Whereas BRS's lowest monthly total was 50.4% of its highest, CWL's lowest was 34.6% of its highest. Put another way the five main summer months May-September saw 58.1% of CWL's annual passenger numbers whereas the same period at BRS saw 52.1%.
There is still a positive in this in that there is undoubtedly a market for further summer expansion, but without winter also upping its game the imbalance would widen.
If CWL could improve its winter performance it would obviously be better placed to attract more year-round airlines. If it had tracked BRS at 20.9% (its best tracking month in 2018 - August) throughout the year CWL's 2018 passenger total would have been well over 200,000 more at over 1.8 million.