Pope Benedict XVI's nine-day visit to Australia is expected to be dogged by controversy over abuse by Roman Catholic priests.
During the 20-hour flight, the Pope addressed media travelling with him on the plane that has been dubbed Shepherd One.
Pilgrims waited at Sydney's aiport for the Pope to arrive, but protests are expected over the abuse claims and against the Vatican's stance on homosexuality and birth control.
The Pope was greeted by Australian Prime Minister Kevin Rudd, who said he was "an honoured guest".
The Pope, who was also welcomed by cardinals, says he will examine how the Catholic Church can "prevent, heal and reconcile" the past crimes of the clergy and apologise for a sex abuse scandal.
The Pope is expected to stay out of the public eye until Thursday when he will attend a World Youth Day festival.