Some other runways appear to go up and down at different points. Answer: No, runways are not flat. They are crowned to help drain water off the sides during rain, and often one end of a runway is higher or lower than the other. When preparing takeoff performance calculations, pilots include the slope of the runway.

Airport runways are angled and oriented based on prevailing wind patterns to ensure maximum safety and performance during takeoff and landing. Airplanes are designed to take off and land into the wind; a headwind provides extra lift over the wings, allowing the plane to get airborne at a lower ground speed and stop more quickly upon landing. If a runway were built in a direction that frequently experienced "crosswinds" (wind blowing perpendicular to the runway), it would make the aircraft difficult to control and potentially lead to accidents. Engineers study decades of meteorological data—often visualized in a "Wind Rose" diagram—to determine the optimal "Primary" runway direction. Many large airports, like Chicago O'Hare or Amsterdam Schiphol, feature multiple runways at different angles (a "cross" or "star" pattern) so that pilots can always find a runway that aligns with the current wind direction, regardless of which way the wind is blowing on a given day. This geometric layout is the "gold standard" for maintaining operational efficiency and passenger safety in all weather conditions.