The disclosed embodiments relate to methods and systems for requesting and retrieving aircraft data during flight of an aircraft. This aircraft data can be used to perform additional monitoring of aircraft sub-systems to detect an abnormal condition, and/or to identify one or more sources that are causing the abnormal condition. In one embodiment, aircraft data for one or more relevant parameters can be requested from the ground, measured on-board the aircraft, and stored in a data file that is then communicated back to personnel on the ground. The real-time aircraft data for one or more relevant parameters can then be analyzed to identify the one or more sources that are causing the abnormal condition.