What typically increases drag during descent in an aircraft?

Extending flaps and lowering landing gear increases drag during descent because both of these actions change the configuration of the aircraft to increase its surface area and alter its aerodynamic profile. When flaps are deployed, they modify the airflow over the wings, creating greater lift at lower speeds but also increasing drag due to the additional surface area and turbulence generated. Similarly, lowering the landing gear exposes a larger surface area to the airflow, which further contributes to drag.

During a descent, pilots may strategically use flaps to control their descent rate and improve lift at lower speeds, but this comes at the cost of increased drag. Consequently, while drag assists in controlling the descent, it’s essential for pilots to balance lift and drag to maintain safe and effective flight conditions during this phase.

The other options do not contribute to a similar increase in drag. For instance, retracting the landing gear significantly reduces drag, and reducing engine power does not inherently increase drag but rather modifies the thrust available without affecting the aircraft's drag profile directly. Climbing to a higher altitude typically alters air density but is irrelevant during a descent and does not focus on drag factors pertinent to the scenario.