This is an 8 mark question, so lets split the answer into three parts so that the examiner can clearly see the various components of this 3+3+2 answer.
In the first paragraph try and state at least four reasons why increased competition is beneficial to passengers, or try and explain two out of three points fully. Although the mark scheme only asks for undeveloped points, it is good to have more or explain a few of them in detail in case one of your arguments isn't on the mark scheme.
The second segment should be written in the same way, except this time discuss the drawbacks of increased competition.
In order to get the final two marks you must offer your personal judgement as a developed conclusion. The easiest way to do this is to discredit either the benefits or drawbacks of increased air competition and at the same time promote the other side of the argument, for example: air transport firms make so much profit that the opportunity cost of investment will always be low, therefore lower profits as a result of increased competition won't affect investment. In fact, the increased competition may stimulate investment, as firms may choose to invest in order to fight off competition and maintain market share. To conclude, increasing competition in the provision of air transport services is unquestionably beneficial to passengers.