 In the final year of his entry-level contract, Alt remained exclusively in the AHL with the Phantoms in the 2015–16 season, appearing in a further 72 games, paired alongside Samuel Morin in a shutdown role, and while also collecting 4 goals and 19 points.On June 26, 2016, he agreed to a one-year, two-way contract to remain with the Flyers.He was familiarly reassigned to return for his fourth season in the AHL in 2016–17.