25F
"2) Equilibrium Glide Phase. This is flight at a constant attitude as
the deceleration due to drag builds up to approximately 1G.
3) Constant Drag Phase. The 1G deceleration is held until the orbiter
enters the Terminal Area Energy Management interface, after which it
is flying as a conventional, but very heavy and fast, glider. This
is usually 52 NM (59 SM, 94 km) from the landing site, at an altitude
of 83,000', and a speed of Mach 2.5 (2500 ft/sec, 760 m/sec) The
orbiter slows to below Mach 1 at about 49,000', 22 NM (25 SM, 40 km)
from the runway. "
The decceleration has to be greater than one. Otherwise it is actually accelerating due to gravity and drag forces not being canceled out.