Point of Equal Time (PET / ETP)

State regulations require for flight planning calculations to take into account the possible failure(s) of one (or more) system(s), such as engine failure(s) and/or loss of cabin pressure (decompression).

These calculations must assure the ability to reach an adequate aerodrome during all phases of flight. For this reason Pont of Equal Time (ETPs) must be calculated in advance.

Source: ICAO Annex 6