  EUSO-Balloon is a pathfinder mission for the Extreme Universe Space
Observatory onboard the Japanese Experiment Module (JEM-EUSO). It was launched
on the moonless night of the 25$^{th}$ of August 2014 from Timmins, Canada. The
flight ended successfully after maintaining the target altitude of 38 km for
five hours. One part of the mission was a 2.5 hour underflight using a
helicopter equipped with three UV light sources (LED, xenon flasher and laser)
to perform an inflight calibration and examine the detectors capability to
measure tracks moving at the speed of light. We describe the helicopter laser
system and details of the underflight as well as how the laser tracks were
recorded and found in the data. These are the first recorded laser tracks
measured from a fluorescence detector looking down on the atmosphere. Finally,
we present a first reconstruction of the direction of the laser tracks relative
to the detector.
