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Log Analyzer

The Log Analyzer at https://rotorlab.app/logs reads a flight log and tells you what is in it: the aircraft and firmware it came from, every mode change, event, error and autopilot message on one timeline, and the flight plotted out as charts. It is free, and you can use it without an account. Reach for it whenever someone hands you a log file and you want to know what the flight looked like before deciding whether it needs deeper investigation.

It reads the autopilot formats — ArduPilot dataflash (.bin), MAVLink telemetry logs (.tlog), PX4 ULog (.ulg) — and the consumer formats: DJI flight records (.txt), Parrot FreeFlight JSON, GUTMA JSON, and Litchi/Airdata/DJI GO flight-log CSV. The format is detected from the file's own bytes, not its name, so a renamed file still reads correctly. See Supported log formats for what each format carries.

Reading a log#

  1. Open https://rotorlab.app/logs.
  2. Drop a .bin, .tlog, .ulg, DJI .txt, .json or .csv file onto the upload area, or click it to browse. Multirotor, plane and rover logs are supported, up to 64 MB.
  3. Press Read log. The file uploads, the analysis runs, and the results replace the upload card.

If the file is over 64 MB the page refuses it before uploading and tells you the size and the limit.

What the analysis shows#

The results page has four parts, top to bottom:

  • Summary tiles. The aircraft (for example "Multirotor (ArduCopter)"), the log source format, the flight time in seconds, and how many events were logged.
  • Charts. Whichever of these the log supports: a flight overview, attitude, motor outputs, throttle, altitude, climb rate, motor RPM, vibration, and battery voltage and current. A log with no chartable series says so instead of showing empty charts.
  • Event timeline. A scrolling table of every mode change, event, error, arm and disarm, and notable autopilot message, each stamped with its time into the flight. Errors are shown in red and warnings in amber.
  • Aircraft & configuration. Values read from the log's parameters: the firmware version, frame class and type, which sensor the altitude came from, the learned hover thrust, the motor idle floor in microseconds, the minimum airspeed on fixed wings, and whether the harmonic notch filter was on.

Format-specific caveats appear as cards above the results. A telemetry log, for example, is a recording of the radio downlink rather than the onboard log, and the page says so.

What happens to your file#

The file is uploaded, read once in memory, and discarded. Nothing is retained: the log is not stored, and the analysis is not saved anywhere. When you press Read another log the previous result is gone.

Daily allowance#

Free readings are counted per day. Signed in, the default allowance is 20 readings per day. Signed out, the default is 5 readings per day, counted against your network address rather than a person (the address is stored only as a hash). The counter appears under the upload card as, for example, "3 of 20 free log readings used today." The Crash Analyzer add-on has no daily limit.

The difference from the Crash Analyzer#

The Log Analyzer describes the log. It does not judge the flight: there is no crash verdict, and no findings. Under the hood the full analysis runs, and the results page tells you which deeper diagnostic channels this specific file supports and how many findings they produced, but not what those findings say.

The Crash Analyzer reads the same file and adds the diagnosis: the verdict and its confidence, a second-by-second readout of the moments before the event, causes ruled in and ruled out, pilot intent from the RC input, estimator health, fitted pack internal resistance, compass interference, accelerometer clipping, a downloadable report, and the option to file the flight to an aircraft's record.