To achieve maximum range in straight and level flight, which parameter should be minimized?

• A. Drag
• B. Weight
• C. Power
• D. Altitude

Answer: (A)

In straight and level flight, you want to use the least thrust possible to maintain the chosen airspeed, which means minimizing the total drag the airplane experiences. The speed that delivers the best lift-to-drag ratio (the maximum L/D) is the one at which drag is minimized for the lift needed to balance weight. Flying at this condition lets the aircraft travel the furthest on a given amount of fuel, since fuel burn per mile is minimized when drag is as small as possible.

Weight, power, and altitude all influence range, but they don’t provide the same direct benefit as reducing drag. Heavier weight raises the lift (and thus induced drag), more power increases fuel burn, and altitude changes air density and performance but the optimal range speed is determined by the best L/D, not altitude alone.