Under what condition would the limits of the 1 in 60 rule apply effectively?

The 1 in 60 rule provides a guideline for determining the maximum altitude gain that can be achieved with reference to the horizontal distance traveled horizontally. It is effectively used under specific temperature conditions to ensure safe navigation and performance calculations in aviation.

When temperatures are below ambient temperature or 15 degrees Celsius, the 1 in 60 rule is applicable because colder air affects aircraft performance, particularly in terms of lift and engine performance. This temperature threshold is critical as it ensures that the performance metrics used in flight planning reflect the lower efficiency of aircraft engines and the denser air associated with colder conditions.

In contrast, temperatures above this threshold may result in different performance outcomes, affecting the reliability of the rule. Therefore, using the 1 in 60 rule effectively under these conditions allows pilots to adequately account for performance variations due to temperature, making flying safer and more efficient.