To limit the probability that passageways between rows of seats will be sloped at the slope of the aisle that is steeper than 1 in 8, which could lead to difficulties in moving along the passageways in an emergency situation, which could lead to delays in the evacuation or movement of persons to a safe place, which could lead to harm to persons.
To limit the probability that passageways between rows of seats will be steeply sloped, which could lead to persons tripping or falling, which could lead to harm to persons.