You have misread something. This is taken from Chapter 15 of the Airplane
Flying Handbook, "Transition to Jet-Powered Airplanes:"

"Certified landing field length requirements are computed for the stop made
with speed brakes deployed and maximum wheel braking. Reverse thrust is not
used in establishing the certified FAR landing distances. However, reversers
should definitely be used in service."

Moreover, the airplane must be brought to a stop (without reversers) in 60
percent of the effective runway length. If the runway is forecast to be wet
or slippery, 15 percent should be added to this distance. These calculations
must be made before takeoff, because a pilot cannot file to an airport where
s/he cannot land within the calculated landing distance under the conditions
forecast to exist.



"Lakeview Bill" wrote in message
om...
Just kidding, but...

I just heard that the NTSB has recommended that pilots no longer be
allowed
to include thrust reversers when they calculate landing distances,
following
the Midway accident.

Fortunately, the FAA usually manages to override this sort of bureaucratic
BS...