A flight phase identification method based on airborne data of civil aircraft

To resolve the flight phase identification errors in the airborne quick access recorder (QAR) trajectory data of civil aircraft, a method of flight phase re-identification was proposed based on the aerodynamic configuration and vertical movements of aircraft. This method comprises four steps: preprocessing of QAR data, identification of vertical movements, construction of a flight state characteristics model, and re-identification of flight phases. A DBSCAN-based local traversal clustering method was used to cluster the trends of pressure altitude to classify vertical movements, and a valid minimum state persistence time was set to eliminate the local flutter in the pressure altitude data. Considering aircraft-to-aircraft differences in flap position and control, fluctuations in airfield QFE, and inaccuracies in the airspeed indicator during low-speed taxiing, a flight-state characteristics model suitable for all types of aircraft and based on state parameters, such as flap switch position, landing gear position, ground speed, and vertical movements, was constructed. The model was used to divide the QAR data into flight state characteristic segments. The relationship model between each flight phase and flight state characteristics was established, and all flight state feature segments were identified as corresponding flight stages combined with landing gear air-ground logic. Three typical sample flights are used as examples, calculation results show that all the flight phases (including go-arounds) are correctly identified and divided, and are also fully consistent with the flap and landing gear states of the aircraft. The flight phase identification error in raw QAR data fields is solved effectively. The flight phases of QAR tracks of 272 268 flights are re-identified, and the success rate is 99.7%. The average durations of non-clean configuration flight phases, such as take-off, initial climb, approach, and landing, are 0.6, 1.9, 6.1 and 4.0 min, respectively, and the average altitudes from the ground are 54, 3 680, 6 030 and 2 500 ft, respectively, which are consistent with the actual flight operation behaviors. Therefore, the flight-phase re-identification method can be applied to numerous flights and provide technical support in analyzing the characteristics of civil aircraft flight phases. 5 tabs, 8 figs, 25 refs.