Dam asked Vann, who was circling the battlefield aboard an L-19 reconnaissance aircraft, to reconnoiter possible landing zones on the east and west sides of Ap Bac, where additional reinforcements could be inserted to launch their attacks. In response, Vann asked his pilot to make low passes over the trees which covered Ap Bac. Although he could not see any VC positions, Vann knew there was a well-fortified position at the south end of the hamlet, due to the impact of the VC's firepower on the Civil Guards since the battle's inception. As Vann's L-19 aircraft flew over the western tree line, the VC watched from their foxholes, but held their fire because they knew the aircraft was trying to draw fire in order to mark their positions. Although Vann was suspicious, he decided it was a better landing zone because the area was tranquil despite the heavy fighting elsewhere.