Which atmospheric conditions will cause the true landing speed of an aircraft to be the greatest?

The true landing speed of an aircraft is influenced significantly by atmospheric conditions, particularly temperature and humidity. When the temperature is high, the air density decreases. Lower air density means that the aircraft requires a higher true airspeed to achieve the same indicated airspeed, which is crucial for maintaining lift during landing. Additionally, high humidity further decreases air density, compounding the effect.

When combining high temperature with high humidity, the air becomes less dense compared to drier, cooler conditions. As a result, to maintain the necessary aerodynamic performance during landing, the aircraft will experience a greater true landing speed. Thus, under these conditions, the aircraft needs to travel faster through the less dense air to ensure safe landing.

Low temperatures and low humidity would result in higher air density, allowing for lower true landing speeds. Cooler temperatures with high humidity would also keep air density higher than the situation with both high temperature and humidity. Consequently, high temperatures combined with high humidity create the scenario where the true landing speed is at its highest, making it the correct choice.