To enable low cost open source ATM simulations the University of Technology Delft is developing an open source ATM simulator Bluesky. A method was developed to identify aircraft performance parameters using ADS-B and other open sources of data. The goal is to determine the operational flight envelope and get estimates for the lift- and drag coefficients. The method streams global ADS-B data from Flightradar24. By making assumptions on wind and flight strategies, estimation can be obtained for aircraft parameters. The nature of these assumptions limit the aircraft types being analyzed to commercial air-craft only. The method measures the operational flight envelope and estimates weight, lift and drag coefficients for multiple phases in flight. Next the operational flight envelope was compared to open data. Here it was found that the estimations showed similar values as the open data and that the operational flight envelope can be estimated using the method. The drag polar was compared to BADA, which showed a consistent underestimation of the drag polar.