When flying at a temperature of 70 degrees F, what is the estimated pressure altitude for a standard flight?

To determine the estimated pressure altitude at a temperature of 70 degrees Fahrenheit, it is important to first understand the concept of pressure altitude in relation to standard atmospheric conditions. Standard pressure altitude is based on an atmospheric condition of 29.92 inches of mercury (inHg) and a temperature of 59 degrees Fahrenheit (15 degrees Celsius) at sea level.

When the temperature deviates from the standard temperature, the pressure altitude changes. For every degree Fahrenheit the temperature is above standard (which is 59°F), the pressure altitude decreases. Conversely, if the temperature is below the standard, the pressure altitude increases.

In this scenario, 70°F is 11 degrees higher than the standard temperature of 59°F. This increase in temperature can lead to a lower pressure altitude than what would be indicated with standard atmospheric conditions. Each degree above 59°F can shift the estimated pressure altitude down approximately 4 feet; therefore, the total decrease at 11 degrees above standard would be about 44 feet.

Starting with the standard pressure altitude at sea level (0 feet), and recognizing that the air pressure at 70°F would be lower due to the increase in temperature, we calculate the adjustment and find that the estimated pressure altitude becomes approximately 676 feet.