Stall Speed is a stat that represents the slowest speed the plane can fly at in combat. A lower stall speed is favored as it allows a Skyrate to slow down enough to catch slow blimps and other planes they would otherwise quickly overtake if at full speed. Due to the physics in Skyrates 2.5 combat, turning at stall is very slow, but may also result in a tighter turning radius than if the plane were at Corner Velocity.
Each plane has its own Stall Speed, which can be altered by Upgrades or Condition Effects. Due to how the game is programmed, a negative Stall Speed is possible on some planes with certain Upgrade combinations; when flying at a negative speed the plane will fly backwards and otherwise function normally. In rare cases Upgrades or Condition Effects may cause Stall Speed to actually be higher than the plane's Speed stat; in this situation the plane cannot change speed during combat (unless using maneuvers) and the plane will constantly fly at stall speed.