Remember high hopes or soft soaps 2014? What happened to the Forsyth report and government agreed recommendations?
The only way the Summit will get anywhere will be to tell McCormack that the GA industry will work to unseat him in his electorate and it will not send delegations to Canberra until he has changed the Act and agreed to the FARs. In addition the reps should tell the same story to all their MPs throughout the country. In other words a real political campaign.
IMHO your chances of getting the Act changed now are probably zero. remember a federal election is coming in 2019. that creates a legislative scramble and a new government is not bound to follow through on any pre-election actions. in fact, from memory a new government won't even have access to the working documents of the old one.
it would be a poor public servant who can't stall you until the election is called. so what's to do at a summit? get your demands sorted and tell the PS what's coming, whether they like it or not and that you are going to make them change via naked political pressure, nothing personal of course.
AND you may soon have a perfect opportunity to test negative political campaigning - assuming the Mayo by-election is called in SA (also fremantle, Longman, Braddon and Perth). threaten to run a campaign via leaflet: "don't vote Downer", etc. this is your only hope. it's the one source of power you have. CASA, RAAF, Qantas and all the other supposed demons can't vote or run political campaigns. You can. hopefully AOPA will take the lead. You CAN make a difference, the election margin between libs and labor in longman was about 1%.
https://en.m.wikipedia.org/wiki/Mayo_by-election,_2018