In the ALIS application, when is a green check mark displayed for the aft index?

In the ALIS application, a green check mark for the aft index is displayed when the measured weight is within acceptable limits as specified for different aircraft types. For narrowbody aircraft, the aft index needs to be in the range of 11 to 89. For the 757, a slightly different range applies where it needs to be between 21 to 89. This range indicates that the aircraft's weight distribution is balanced and within operational safety parameters, ensuring that the center of gravity is maintained for safe flight operations.

When the aft index lies within this specified range, it promotes optimal aircraft performance and stability. Operating within these limits helps ensure that the aircraft can handle normal flight maneuvers and does not compromise safety due to improper weight distribution.

Other ranges mentioned in the other options would not provide a green check mark because they either fall outside the safe operating parameters for the specific type of aircraft or indicate conditions that could potentially lead to safety issues during flight.