Predecessor David Moyes was given just 10 months by the board as he failed to lead United to the Champions League after replacing Sir Alex Ferguson at the helm.
Van Gaal claimed just eight points from his first six Barclays Premier League games and oversaw a humiliating 4-0 defeat to MK Dons in the Capital One Cup.
But the Dutchman, who penned a three-year deal in the summer, is certain he will be given time to get it right at United and is sure he will lead them back to the Champions League before 2017.
"I didn't have to come here to Manchester United
They asked me," he told national newspapers.
"And I will take United back into the Champions League yes, but not at once.
"There is a trajectory and a process of three years
I have signed a three-year contract
Believe me, I shall finish that."
United's defence has come in for much criticism since Van Gaal's arrival, but the manager was candid in admitting that it is experience and leadership that is currently a major factor lacking from his dressing room.
"At the time I was coming to the club, big leaders were leaving - (Patrice) Evra, (Nemanja) Vidic, (Rio) Ferdinand," he said
"They were big leaders
"Also, leadership is a process - you don't go from one day to the next and become a leader
"It's a process and now a lot of players are in that process."
Source : PA
Source: PA