The full inquest into the death of a schoolboy during a trip to Morocco with his classmates will begin on Monday.
Samuel Boon, 17, collapsed as he took part in a trek in blazing temperatures in the north African country in July last year.
The World Challenge trip was due to last 14 days and included a six-day trek to Amezmiz in the High Atlas foothills.
A five-day full inquest hearing is due to begin today, before a coroner sitting at Bromley Civic Centre in south east London.
The teenager's father, Ken Boon, said: "Sam collapsed on the second day of the trek and had to wait for two hours by the roadside in extreme heat for evacuation, which came in the form of a minibus rather than an ambulance.
"Whilst the expedition leader and the school staff did everything they could on the ground to try to save him, they, along with our son, were badly let down and we hope the inquest will answer our questions as to why this happened."
Eleven pupils from the Business Academy in Bexley, south east London, went on the trip, and had raised funds to support the expedition.
They had been due to work on a rural project for seven days after the trek, but the trip was cut short after Samuel died.
At the time of his death, temperatures in the region were reported to have risen as high as 49C (120.2F).