What is expected at FL350 when the ambient temperature is warmer than standard?

When the ambient temperature is warmer than standard at Flight Level 350 (FL350), the pressure altitude will be higher than the indicated altitude. The reason for this is based on the principles of atmospheric pressure and temperature.

In aviation, pressure altitude is defined as the height above the standard datum plane (which is based on the International Standard Atmosphere, ISA). The ISA assumes a standard temperature of 15 degrees Celsius at sea level, decreasing by approximately 2 degrees for every 1,000 feet of altitude gain. If the actual temperature is warmer than this standard, the air density decreases compared to what is expected at standard temperatures.

Because of this warmer temperature, the altimeter will read lower than it should at that pressure level. Therefore, the aircraft is effectively at a higher altitude than what is indicated on the altimeter, resulting in pressure altitude being higher than the actual altitude indicated by the aircraft's altimeter.

The notations regarding lower than pressure altitude, cannot be determined, and equal to pressure altitude are incorrect interpretations of how temperature affects pressure readings within the atmosphere. It's essential for pilots and dispatchers to understand this relationship to ensure accurate altitude management and safety during flight operations.