The Airports Commission requested ITF/SEO to provide technical assistance with analysing responses that pertain to the previous work undertaken by the ITF/SEO. This report assesses the submissions by the stakeholders in relation to competition impacts and compares them with the ITF/SEO results and the literature. Specifically, we review the following studies:1. InterVISTAS (2014). The Importance of Airport Competition on Air Fares Paid by Consumers. November 20142. Frontier Economics (2014). Impact of airport expansion options on competition and choice. A report prepared for Heathrow Airport Ltd, April 2014.3. Gatwick Airport Ltd. (2015). Supporting Traffic & competition analysis.4. British Airways (2015). British Airways response to the Airports Commission Public Consultation on new runway capacity in the South East. 3 February 2015.5. CAA (2015). CAA response to the Airports Commission consultation: increasing the UK’s long-term capacity.6. CBI (2015). Boosting capacity where it matters most- the nub is the hub. The CBI’s position on future aviation capacity.7. Virgin Atlantic (2015). Virgin Atlantic Response: Airports commission final consultation on shortlisted options for new capacity.8. EasyJet (2015). EasyJet response to the Airports Commission consultation.9. Heathrow Airport Main submission.The note is focused on discussing the competition impact assessments as requested by the Airports Commission. We do not consider the likelihood of airline responses and Airports Commission scenarios. The focus of our review will be on the first two studies, with a more concise review of the other submission, as far as relevant.