Pilot report

From Glossary of Meteorology

pilot report

(Commonly contracted PIREP;
also called aircraft report.) A report of in-flight weather by an aircraft pilot or crew member.

A complete report includes the following information in this order: location and/or extent of reported weather phenomena; time of observation; description of phenomena; altitude of phenomena; type of aircraft (only with reports of turbulence or icing). This term is also applied to more informal and less complete reports of weather aloft as well as to post-flight reports filed after landing.
Compare aircraft observation.