With no one on base, all fly balls (or line drives) belong to the plate umpire. On all fly balls and line drives to the outfield the base umpire will come into the infield and pivot. The plate umpire will assume responsibility for all fair/foul, catch/no catch. The thinking here is that the plate umpire will be no further away on the smaller field than the base umpire would be on the full size field. The plate umpire already has everything in front of him/her and it is a simple matter to move up the line on fair/foul or develop an angle for the catch/no catch.
   Little League recommends that the base umpire not go out, but there may be instances where the experienced umpire judges that it is necessary to go out for better coverage of a trouble ball.  

If a fly ball or line drive is hit from the center fielder straight in all the way to the right field line and the base umpire, using the "pause-read-react" technique, decides NOT to go out, then the responsibility of the ball reverts to the plate umpire. If this is the case, the base umpire will take a pivot and pick up the batter-runner, making all decisions at 1st, 2^nd, or 3^rd on the batter-runner.
   If the base umpire does not go out, then as just mentioned, the responsibility of any fly ball or line drive to the outfield belongs to the plate umpire. The plate umpire will come out from behind the plate in the direction the ball is hit and will make all catch/no catch and fair/foul decisions on the ball. If the ball is a "routine" fly ball, the plate umpire will come out from behind the plate in the direction the ball is hit and will go no farther than an imaginary line between 1^st and 3^rd to observe the play. If the play results in a routine catch, the plate umpire will make the signal and should audibly inform his/her partner, "That's a catch, Sam", so that his/her partner is aware the ball has been caught. If the ball is dropped, the plate umpire should call and signal, "No catch! No catch!" The plate umpire should be completely stopped for these decisions.
   On fly balls to the outfield, if the base umpire does not go out and the play results in a difficult play (for example: a diving catch, a home run, a ball hit off the wall, a fair/foul decision, a catch at the warning track, etc.), then the plate umpire should come out in front of the plate in the direction the ball is hit and go as far as he/she can towards the ball to make his/her decision. If the play results in a "tough" catch (shoestring catch, diving catch, catch after which the fielder falls down, etc.), the plate umpire should call and signal (and sell), “That’s a catch! That's a catch!" (Signaling the catch should be done with the right arm fully extended upward and right hand in a fist.) If this type of play results in a "tough" no catch, the plate umpire again should come out in the direction the ball was hit as far as possible and sell the call, "No catch! No Catch!" Again, the plate umpire should be stopped to make such a call. As soon as he/she has made the call, the plate umpire should retreat in a straight line back towards home plate for any possible play there.
   Summarizing on fly balls (or line drives) hit to the outfield with no one on, (1) if the base umpire does not go out, the decision on the ball belongs to the plate umpire. If it is a "routine" play, the plate umpire should come out no farther than an imaginary line between 1st and 3^rd. If it is a ''tough'' play, then the plate umpire should come out as far as possible in the direction the ball was hit. Also, the plate umpire should be completely stopped to make all of these decisions.