Fair or Foul?

[hawk65]

I was base umpire in C position. Batter hits a shot down 1st base line. Plate umpire didn't pick up the ball until it was well beyond the 1st base bag and didn't have any idea whether it was fair or foul. I had no idea from my position so could offer no help and he of course has to make a timely call. Is the default call "always fair if I didn't see it" or "always foul if I didn't see it" or do you just guess and live with it? Or what clues do you use to make an educated guess?

[umpharp]

I guess the default would be a fair ball, but its not really a default call as the PU should have at least a guess at fair/foul
If I'm in your position, I'm moving like its a fair ball until I hear the PU say "FOUL." Until that time, I'm begining to move inside cause I'm assuming that we have a base hit down the line.
After the play, I'm gonna help my partner by keeping the assist coaches away while the head coach discusses the call with him.