# Aircraft thrust calculation

I had a question regarding thrust calculation for an aircraft during cruise. For an aircraft flying at a constant cruise altitude and a constant Mach number (level unaccelerated flight), what exactly is the weight we use in the equation T = W/(L/D) while calculating the thrust?

What I understand is that since the mass of the aircraft is continually reducing due to constant fuel consumption, therefore the lift requirement will change. Assuming a constant L/D ratio, that implies the drag will change leading to a constant change in the thrust. Therefore the cruise thrust is not a constant value. So how can we apply the above equation for a calculation of the thrust anyway? Is it a thrust at some specific point during the cruise?