Rule 1 (Mandatory)
Passenger load of 177 or less = Block off row 3 and 4.
Rule 2 (Applicable only for aircraft balance purposes, when advised by
Captain or dispatcher)
With 129 or fewer passengers carried, front seat rows 3 through 8 and
aft 4
seat rows must be blocked off by lowering the tray tables. The tray
tables must be re-stowed before take off.