When must a heavier aircraft begin its descent compared to a lighter aircraft?

A heavier aircraft must begin its descent earlier than a lighter aircraft primarily due to the differences in their performance characteristics. Heavier aircraft require more lift, which translates into the need for a longer distance to descend and slow down safely. This is due to the increased inertia and momentum that comes with added weight, making it necessary for these aircraft to initiate their descent well in advance to align properly with the approach profile for landing.

Additionally, the effects of gravity play a role in this requirement. Heavier aircraft have a steeper glide slope and need to manage energy more carefully to avoid excessive speed on approach. Starting the descent earlier allows pilots of heavier aircraft to establish a proper rate of descent that promotes a smooth and controlled approach to landing.

In contrast, lighter aircraft, having less mass, can typically begin their descent later and still remain within a safe and manageable glide slope, as they can reduce speed more rapidly and respond more quickly to changes in altitude. This difference in operational handling highlights the importance of weight in flight dynamics, dictating the critical timing of descent for safe landing.