The first (pilot) episode of the series, "An Unearthly Child '', had to be re-recorded owing to technical problems and errors made during the performance. During the days between the two tapings, changes were made to costuming, effects, performances, and the script (which had originally featured a more callous Doctor, and Susan doing unexplained things such as flicking ink on paper and folding it to produce a symmetrical pattern, and then tracing shapes over the pattern). This second version of "An Unearthly Child '', the first episode of the very first serial, was transmitted at 5.15 pm on 23 November 1963, but due to both a power failure in certain areas of the country and the overshadowing news of US President John F. Kennedy 's assassination, it drew minimal comment and was repeated the following week immediately before the second episode.
when did the first doctor who episode air
5.15 pm on 23 November 1963