Is it true: Rendlesham Forest Incident?

There's no solid evidence for it.

The Rendlesham Forest incident involves USAF personnel reports from two nights (26 and 27-28 December 1980) near the US-operated RAF Woodbridge base. The reports are real and documented: Lt. Col. Charles Halt's 13 January 1981 memo (which misdates the events by a day), the audio tape Halt made on the second night, and the written statements of the first-night airmen. The claim that an alien or otherwise unexplained craft landed, however, has not cleared our evidence bar: no physical evidence, authenticated radar or sensor record, or official file supports a non-human craft, and the best-supported explanations for the lights are mundane. (1) The first-night sighting at about 3 a.m. on 26 December coincided with a very bright fireball logged by the British Astronomical Association at about 02:50 UT. (2) The flashing light the first-night patrol chased was identified by two of the airmen themselves (Burroughs and Cabansag) as a lighthouse, and the police who attended saw only the Orford Ness light, roughly five to seven miles away. (3) The three "landing" depressions were identified by police and a local forester as rabbit scrapings, and the radiation readings were background level (similar readings were recorded half a mile from the site; the Geiger counter's makers called them of little or no significance). (4) The touch-the-craft and binary-code accounts do not appear in any 1980 statement and first surfaced decades later (Penniston's notebook was shown on television in 2003, the binary-code claim in 2010). Halt's second-night observations are attributed by Ian Ridpath to the same lighthouse plus bright stars such as Sirius; that attribution is an inference rather than a proven match, Halt and Penniston still reject it, and this page does not claim it explains every report. UK MoD records (the Rendlesham file was first released in 2001, with more files opened at The National Archives in 2009-2010) show a cursory MoD review in 1981, nothing on radar, no evidence of anything intruding into UK airspace, and a stated position of "no defence significance" rather than a suppressed investigation. The case is among the best-documented UFO reports in military records, but being well documented does not make the extraordinary explanation true.