Point of Equal Time
The Point of Equal Time (PET), also known as the Critical Point (CP), is the location where it will take you the same amount of time to fly to either of two landing sites. The PET helps you determine which of the two landing sites is closer in case of an emergency. These two locations could be the start and end points of your flight, or any other two suitable places.
Point of Equal Time Formula
Deriving the Point of Equal Time Formula
The distance between you and the two landing sites is known:
The PET is somewhere between the two landing sites:
The PET is the distance from landing site a where it will take you the same amount of time to fly to either of the two landing sites; and time is defined as distance over speed:
Solving this equation gives the PET formula: