ru.wikipedia.org/wiki/%D0%9F%D0%B8%D0%BB%D0%BE%...
"A "television pilot" (also known as a "pilot", "pilot episode", and "series premiere") is a standalone episode of a television series that is used to sell the show to a television network. At the time of its creation, the pilot is meant to be the testing ground to gauge if a series will be successful, and is therefore a test episode of an intended television series.
[...]
Most pilots are never publicly screened if they fail to sell a series. If a series eventuates, pilots are usually - but not always - broadcast as the introductory episode of the series."
en.wikipedia.org/wiki/Television_pilot
Меня очень достало то, что часть людей называют пилотами первую серию любого сезона сериала. Выражение "пилот нового/второго/пятого/десятого сезона", которое я иногда встречаю - это какая-то выдумка непонятно кого, такого быть не может.