He was rushed to theatre to remove the fluid around his brain but, because of the position, only part of the growth could be removed. Six weeks later it had doubled in size so he had another eight hours of surgery, spending his eighth birthday in hospital.
He cannot regain his lost sight and has a teacher's aide at school. The good news is Jackson has just finished chemotherapy - but he will never be completely free of the tumour.
"It is devastating to think that if he had been diagnosed correctly his eyesight could have been saved," says Rosie.
Brain tumours are the second most common cancer type in young people after leukaemia.
Jackson's mum said the trip was a great escape for the family from Whangapararaoa.
"He got up this morning and said 'yesterday was the best day ever Mum'. And just now he said 'actually I have changed my mind. Today is the best day ever'. It just keeps getting better and better."
Josie Spillane from Cure Kids said: "It is fantastic to see the kids out having so much fun. For many it is the first time they have been on a plane, the first time they have seen snow. Each of these phenomenal children live with an illness that Cure Kids funds research into and they inspire us to find ways to improve their lives, prolong their lives and our ultimate goal of finding a cure."