Wiktionary
vb. To forget one's train of thought or temporarily misplace an item or its place in a sequence.
Usage examples of "lose track".
It was easy to lose track of time in that long traverse of darkness.
Call's silences had a way of making him lose track of his thoughts--some of which were perfectly good thoughts, in their way.
But the Foundation lost track of you-will lose track of you-and your date of death never got into the records.
Just as suddenly, I realized that this was a dream and that I had dreamt it several times before only to lose track of it upon awakening.
In cases like that you tend to lose track of everything except survival.
You lose track of time, you lose track of yourself, and you only stop when they stop coming.
They could leave their search radars on and almost certainly have them destroyed or turn them off and lessen the chance-and completely lose track of the overhead air battle.