My other question is- why only now does CASA say that you cannot operate when the temp is outside the P chart temperature? They've been in existence for decades, and it's not a new idea.
I'm not necessarily brave enough to take on the potential battle.
Had an experienced back in the 70s where an aircraft departed in high temps 40+ but with a 20Kt wind that allowed a shorter, but into wind, runway to be used.
The Alphabet Authority (cannot remember what they were called at that particular point of time) tried to ping the pilot for departing of the runway as it was too short based on the "P" charts that only presented calculations to a temp of 35c and a wind less that the actual wind.
But using the manufacturers charts the aircraft could depart. The Alphabet Authority pointed out that we had to use the "P" Charts. I informed the Alphabet Authority that their "P" charts did not reflect the conditions experienced in Australia and therefore we were being forced to use charts unfit for purpose.
I did not hear back from Alphabet Authority.