In the "Father's Day" episode of Dr. Who (2005), The Doctor claims that, once he has the Tardis, he will fix the damage to time that Rose causes when she prevents her father's death and banish the Reapers. However he indicates that after his "fix" Rose's father will still be alive.
Ultimately, the damage to time was corrected when Rose's father allows himself to be killed and this answer indicates that only Peter Tyler's death would have fixed the paradox.
It seems Peter Tyler's death is an integral part of the natural timeline. Most likely because had he lived, Rose might never have met the Doctor, and Bad Wolf would not have played out the way it did.
Given this, how was The Doctor planning to "fix time" with the Tardis in a way that would have allowed Rose's dad to remain alive?