For clarity:
Quote:
Part 25 > Section 301 - Loads
(a) Strength requirements are specified in terms of limit loads (the maximum loads to be expected in service) and ultimate loads (limit loads multiplied by prescribed factors of safety). Unless otherwise provided, prescribed loads are limit loads.
(b) Unless otherwise provided, the specified air, ground, and water loads must be placed in equilibrium with inertia forces, considering each item of mass in the airplane. These loads must be distributed to conservatively approximate or closely represent actual conditions. Methods used to determine load intensities and distribution must be validated by flight load measurement unless the methods used for determining those loading conditions are shown to be reliable.
(c) If deflections under load would significantly change the distribution of external or internal loads, this redistribution must be taken into account.
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I think you are confusing ultimate loads with limit loads. If aircraft were even close to limit loads during an
average take off and landing, they would be falling out of the sky. Limit loads are the
maximum load expected during service so the hardest landings/takeoffs/turbulence/manouvers, etc. expected.