What is meant by the relationship between IAS and LSS at a constant Mach number?

The relationship between Indicated Airspeed (IAS) and Lift Stall Speed (LSS) at a constant Mach number is characterized by the fact that when LSS decreases, IAS also decreases.

At a constant Mach number, which represents the ratio of the true airspeed to the speed of sound, the factors influencing air density and temperature become crucial. Lift Stall Speed is the minimum speed at which an aircraft can maintain level flight without stalling, and it is affected by altitude due to changes in air density. As the altitude increases, air density decreases, leading to a decrease in the LSS.

Consequently, with a reduction in LSS, for a given Mach number to be maintained, the IAS must also decrease. This is because, at a lower stall speed, the aircraft must fly slower to avoid reaching the stalling threshold relative to the lift being generated. Therefore, this intrinsic connection between stall speed and indicated airspeed ensures that as LSS drops, the IAS will likewise decrease, making this answer accurate in reflecting the relationship under these conditions.