What is the purpose of a CG envelope in flight operations?

• A. To determine allowed engine configurations
• B. To schedule fuel stops
• C. To visualize safe combinations of weight and CG for safe operation
• D. To set landing gear retraction schedules

Answer: (C)

The CG envelope is all about keeping the airplane controllable and within safe structural limits by restricting how it can be loaded. It maps the permissible combinations of total weight and forward or aft center of gravity, showing the regions where the airplane has enough longitudinal stability and enough elevator authority to fly safely, take off, maneuver, and land.

Sticking inside this envelope ensures you won’t end up with a weight distribution that makes the aircraft nose-heavy or tail-heavy, which could lead to excessive stick forces, loss of control authority, or reaching structural limits. It also accounts for how weight shifts during phases of flight (fuel burn, payload changes) and for different configurations (such as flaps or gear down), so loading plans, fuel planning, and preflight weight/ balance calculations all aim to keep the aircraft within these boundaries.

This concept isn’t about choosing engine configurations, planning fuel stops, or scheduling landing gear retraction—the envelope specifically defines safe weight and CG combinations for flight.