(a) For each airplane subject to this part, the SAR of an airplane must be determined by either:

1. (1) Direct flight test measurements; or

2. (2) Using a performance model that is:

   1. (i) Validated by actual SAR flight test data; and
   2. (ii) Approved by the FAA before any SAR calculations are submitted.

(b) For the airplane model, establish a 1/SAR value at each of the following reference airplane masses:

1. (1) High gross mass: 92 percent MTOM.
2. (2) Low gross mass: (0.45 * MTOM) + (0.63 * (MTOM^0.924)).
3. (3) Mid gross mass: simple arithmetic average of high gross mass and low gross mass.