Text in force at 25-153: from 25-38, effective 1 Feb 1977.
The passenger aisle width at any point between seats must equal or exceed the values in the following table: Passenger seating capacity Minimum passenger aisle width (inches) Less than 25 inches from floor 25 inches and more from floor 10 or less-------------------------------------------- 112 15 11 through 19--------------------------------------- 12 20 20 or more------------------------------------------- 15 20 [1A narrower width not less than 9 inches may be approved when substantiated by tests found necessary by the Administrator.]
41 FR 55466 · Source