Downloading and Analyzing Data Logs in Mission Planner

Dataflash logs are stored on the autopilot and can be download after a flight. By default, they are created after you first arm the vehicle. This topic explains how to configure and access Dataflash logs.

Depending on the autopilot type and configuration, the dataflash logs may be saved on a SD card, dataflash chip or streamed over MAVLink telemetry ports. The MAVLink option does require a high-speed telemetry port, typically 921600 baud.


Telemetry logs (also known as “tlogs”) collect similar information to dataflash logs (see Diagnosing problems using Logs for more information).


If your vehicle is having trouble producing dataflash logs - including the infamous “No IO heartbeat” diagnostic message - try a different SD card. You may also choose to test the card using a dedicated tool, such as H2testw. Low board voltages are also known to cause logging issues.

Logging Parameters

Some commonly used parameters are:

  • LOG_BACKEND_TYPE : Bitmask for where to save logs to. Common values are “0” to disable logging, “1” to log to SD card file, “2” to stream over MAVLink and “4” to log to board dataflash memory, if equipped.
  • LOG_BITMASK : Bitmask for what items are logged. Normally, use default value, or “0” to disable logging.
  • LOG_DISARMED : Setting to one will start logging when power is applied, rather than at the first arming of the vehicle. Usefull when debugging pre-arm failures.
  • LOG_FILE_DSRMROT : Setting this bit will force the creation of a new log file after disarming, waiting 15 seconds, and then re-arming. Normally, a log will be one file for every power cycle of the autopilot, beginning upon first arm.
  • LOG_FILE_MB_FREE : This parameter sets the minimum free space on the logging media before logging begins. If this is not available, then older logs will be deleted to provide it during initialization. Default is 500MB.

Automatic Analysis of logs


Mission Planner: Start LogAnalysis

The simplest analysis is to generate a basic automated report that will highlight common problem areas. For that, click on “Log Analysis” and select a log that you’ve already saved to the MissionPlanner/logs directory. They will be in folders named after the vehicle type, such as QUADCOPTER or ROVER. Once you pick the log you want, it will generate a report that looks like this:


Manually review a log

For more detailed analysis, click on “Review a Log” and select a log that you’ve already saved to the MissionPlanner/logs directory. Once again, they will be in folders named after the vehicle type, such as QUADCOPTER or ROVER.

Steps to review a log downloaded from the internet, or your vehicle

For DataFlash logs, with a .bin or .log extension:

  1. Download the log file. Note the place on your computer to which it is downloaded. (For example, it might be C:\Downloads)
  2. Open Mission Planner
  3. Navigate to the “Flight Data” page (top left)
  4. Select the “Dataflash Logs” tab (mid-screen, left side)
  5. Select the “Review a Log” button.
  6. A standard Windows “select a file” box will let you go find the .bin file that you downloaded, at the place that you downloaded it. (Per the example above, it is in C:\Downloads) Choose that file.
  7. After reading the log, a Manual Log Review window will be open, which allows you to plot data from the log for inspection. (see below)

Reviewing the log data

Once you pick the log you want, you will get charts such as the below. The basic format of the dataflash is:

  • Line numbers appear on the very left side of the viewer
  • Software version and board type appear at the top
  • FMT messages are next which tell the mission planner the column headers for each message type
  • PARM rows which show each parameter (in the order in which they appear in the eeprom) along with their value at the beginning of the flight
  • Flight data messages including GPS, IMU, etc.

Graph any flight data by first clicking on the appropriate row, you should see the column headers update appropriately. Next find the column you wish to graph, click on it and then push the “Graph this data” button. In the example above the ATT’s Roll-In and Roll data have been graphed. The mouse’s scroll wheel can be used to zoom in or out. You may also select an area of the graph to zoom in on it. Zoom out by right-mouse-button clicking and selecting “Set Scale to Default”. Here’s a mini tutorial on using this feature. You may also filter on just the first column (the flight data message type) by clicking on the first column and selecting the message type from the drop-down. This is very useful especially for viewing the different flight modes (called “MODE” messages) used during the mission. Click the first column again but press “Cancel” to clear the filter.


Setting what data you want recorded

The LOG_BITMASK parameter controls what messages are recorded in the dataflash


Message Details (Copter specific)


Many messages are detailed in the Onboard Message Log Messages page in each vehicle’s wiki section.

ATT (attitude information):

DesRoll The pilot’s desired roll angle in degrees (roll left is negative, right is positive)
Roll The vehicle’s actual roll in degrees (roll left is negative, right is positive)
DesPitch The pilot’s desired pitch angle in degrees (pitch forward is negative, pitch back is positive)
Pitch The vehicle’s actual pitch angle in degrees (pitch forward is negative, pitch back is positive)
DesYaw The pilot’s desired heading in degrees with 0 = north
Yaw The vehicle’s actual heading in degrees with 0 = north
ErrRP The average size of the roll/pitch error estimate (values between 0 and 1)
ErrYaw The average size of the yaw error estimate (values between 0 and 1)

ATUN (auto tune overview):

  Axis: 0 = Roll, 1 = Pitch
TuneStep 0 = Returning towards Level (before or after a test), 1 = Testing (i.e. performing a twitch to test response), 2 = Updating gains (twitch completed and gains adjusted)
RateMin Minimum recorded rate during this test
RateMax Maximum recorded rate during this test
RPGain Rate P gain value being tested
RDGain Rate D gain value being tested
SPGain Stabilize P gain being tested

ATDE (auto tune step details):

Angle Angle of the copter in centi-degrees for the axis being testedx
Rate Rate of rotation of the copter for the axis being tested

CAM (time and position when camera shutter was activated):

GPSTime The GPS reported time since epoch in milliseconds
Lat The accelerometer + GPS latitude estimate
Lng The accelerometer + GPS longitude estimate
Alt The accelerometer + barometer estimated altitude in cm above ground
Roll The vehicle roll angle in centi-degrees
Pitch The vehicle pitch angle in centi-degrees
Yaw The vehicle’s heading in centi-degrees

CMD (commands received from the ground station or executed as part of a mission):

CTot The total number of commands in the mission
CNum This command’s number in the mission (0 is always home, 1 is the first command, etc)
CId The MAVLink message id
Copt The option parameter (used for many different purposes)
Prm1 The command’s parameter (used for many different purposes)
Alt The command’s altitude in meters
Lat The command’s latitude position
Lng The command’s longitude position

COMPASS (raw compass, offset and compassmot compensation values):

Field Description
MagX, MagY. MagZ Raw magnetic field values for x, y and z axis
OfsX, OfsY, OfsZ Raw magnetic offsets (will only change if COMPASS_LEARN parameter is 1)
MOfsX, MOfsY, MOfsZ Compassmot compensation for throttle or current

CURRENT (battery voltage, current and board voltage information):

Thr Pilot input throttle from 0 ~ 1000
ThrInt Integrated throttle (i.e. sum of total throttle output for this flight)
Volt Battery voltage in volts * 100
Curr Current drawn from the battery in amps * 100
Vcc Board voltage
CurrTot Total current drawn from battery

CTUN (Control, Throttle and altitude information):

TimeUS Time stamp for messages in microseconds (can be ignored)
ThI The pilot’s throttle in as a number from 0 to 1000
ABst Angle Boost: throttle increase (from 0 ~ 1000) as a result of the copter leaning over (automatically added to all pilot and autopilot throttle to reduce altitude loss while leaning)
ThO Final throttle output sent to the motors (from 0 ~ 1000). Normally equal to ThrI+ABst while in stabilize mode.
ThH Estimated throttle required to hover throttle in the range 0 ~ 1
DAlt The Desired Altitude while in AltHold, Loiter, RTL or Auto flight modes. It is influenced by EKF origin, which in 3.5.X is corrected by GPS altitude. This behaviour is turned off in 3.6.X and can be turned on with EKF_OGN_HGT_MASK.
Alt The current EKF Altitude
BAlt Barometer Altitude: The altitude above ground according to the barometer
DSAlt Desired distance in cm from ground or ceiling (only visible if Sonar is available)
SAlt Sonar Altitude: the altitude above ground according to the sonar (Only visible of Sonar is available)
TAlt Terrain altitude (not used by default)
DCRt Desired Climb Rate in cm/s
CRt Climb Rate in cm/s
N Harmonic notch current center frequency for gyro in Hz

D32, DU32 (single data values which are either signed 32bit integers or unsigned 32bit integers):


Identification number for the variable. There are only two possible values:

  • 7 = bit mask of internal state (The meaning of individual bits can be found in the def’n of the ap structure
  • 9 = simple mode’s initial heading in centi-degrees

EKF (Extended Kalman Filter):

Log information here (Dev Wiki). Overview here.

ERR (an error message):

SubSystem and Error codes listed below

Subsys ECode and Description
2 = Radio
  • 0 = Errors Resolved
  • 2 = Late Frame : no updates received from receiver for two seconds
3 = Compass
  • 0 = Errors Resolved
  • 1 = Failed to initialise (probably a hardware issue)
  • 4 = Unhealthy : failed to read from the sensor
5 = Radio Failsafe
  • 0 = Failsafe Resolved
  • 1 = Failsafe Triggered
6 = Battery Failsafe
  • 0 = Failsafe Resolved
  • 1 = Failsafe Triggered
8 = GCS Failsafe
  • 0 = Failsafe Resolved
  • 1 = Failsafe Triggered
9 = Fence Failsafe
  • 0 = Failsafe Resolved
  • 1 = Altitude fence breach, Failsafe Triggered
  • 2 = Circular fence breach, Failsafe Triggered
  • 3 = Both Alt and Circular fence breached, Failsafe Triggered
  • 4 = Polygon fence breached, Failsafe Triggered
10 = Flight mode Change failure

Vehicle was unable to enter the desired flight mode normally because of a bad position estimate

See flight mode numbers here

11 = GPS
  • 0 = Glitch cleared
  • 2 = GPS Glitch occurred
12 = Crash Check
  • 1 = Crash into ground detected. Normally vehicle is disarmed soon after
  • 2 = Loss of control detected. Normally parachute is released soon after
13 = Flip mode 2 = Flip abandoned (not armed, pilot input or timeout)
15 = Parachute
  • 2 = Not Deployed, vehicle too low
  • 3 = Not Deployed, vehicle landed
16 = EKF Check
  • 0 = Variance cleared (position estimate OK)
  • 2 = Bad Variance (position estimate bad)
17 = EKF Failsafe
  • 0 = Failsafe Resolved
  • 1 = Failsafe Triggered
18 = Barometer
  • 0 = Errors Resolved
  • 4 = Unhealthy : failed to read from the sensor
19 = CPU Load Watchdog
  • 0 = Failsafe Resolved
  • 1 = Failsafe Triggered (normally vehicle disarms)
20 = ADSB Failsafe
  • 0 = Failsafe Resolved
  • 1 = No action just report to Pilot
  • 2 = Vehicle avoids by climbing or descending
  • 3 = Vehicle avoids by moving horizontally
  • 4 = Vehicle avoids by moving perpendicular to other vehicle
  • 5 = RTL invoked
21 = Terrain Data 2 = missing terrain data
22 = Navigation
  • 2 = Failed to set destination
  • 3 = RTL restarted
  • 4 = Circle initialisation failed
  • 5 = Destination outside fence
23 = Terrain Failsafe
  • 0 = Failsafe Resolved
  • 1 = Failsafe Triggered (normally vehicle RTLs)
24 = EKF Primary changed
  • 0 = 1st EKF has become primary
  • 1 = 2nd EKF has become primary
25 = Thrust Loss Check
  • 0 = Thrust Restored
  • 1 = Thrust Loss Detected (altitude may be prioritised over yaw control)
26 = Sensor Failsafe (Sub)
  • 0 = Sensor Failsafe Cleared
  • 1 = Sensor Failsafe Triggered
27 = Leak Failsafe (Sub)
  • 0 = Leak Failsafe Cleared
  • 1 = Leak Detector Failsafe Triggered
28 = Pilot Input Timeout Failsafe (Sub only)
  • 0 = Pilot Input Failsafe Cleared
  • 1 = Pilot Input Failsafe Triggered
29 = Vibration Failsafe
  • 0 = Excessive Vibration Compensation De-activated
  • 1 = Excessive Vibration Compenstaion Activated

EV: (an event number). The full list of possible events can be found in AP_Logger.h but the most common are:

10 Armed
11 Disarmed
15 Auto Armed (pilot has raised throttle above zero and autopilot is free to take control of throttle)
18 Land Complete
25 Set Home (home location coordinates have been capture)
28 Not Landed (aka Takeoff complete)

GPA: (Global Position Accuracy)

VDop Vertical dilution of precision, a unitless measure of precision
HAcc Horizontal Accuracy as reported by the GPS module, in meters
VAcc Vertical Accuracy as reported by the GPS module, in meters
SAcc Speed accuracy as reported by the GPS, in m/s/s
Flag to indicate if the GPS is reporting vertical velocity
0 No vertical velocity data 1 GPS has vertical velocity data
SMS The autopilot time in milliseconds that the accuracy/GPS position data is associated with.
Delta The time between when the previous GPS message and the current GPS message was parsed by the autopilot, in milliseconds


Status 0 = no GPS, 1 = GPS but no fix, 2 = GPS with 2D fix, 3 = GPS with 3D fix
Time The GPS reported time since epoch in milliseconds
NSats The number of satellites current being used
HDop A measure of gps precision (1.5 is good, >2.0 is not so good)
Lat Latitude according to the GPS
Lng Longitude according to the GPS
RelAlt Accelerometer + Baro altitude in meters
Alt GPS reported altitude (not used by the autopilot)
SPD Horizontal ground speed in m/s
GCrs Ground course in degrees (0 = north)

IMU (accelerometer and gyro information):

GyrX, GyrY, GyrZ The raw gyro rotation rates in radians/second
AccX, AccY, AccZ The raw accelerometer values in m/s/s

Mode (flight mode):

Mode The flight mode displayed as a string (i.e. STABILIZE, LOITER, etc)
ThrCrs Throttle cruise (from 0 ~ 1000) which is the autopilot’s best guess as to what throttle is required to maintain a stable hover
Rsn Reason for mode change (TX command, failsafe, etc) . The meaning of code values can be found in ModeReason

NTUN (navigation information):

WPDst Distance to the next waypoint (or loiter target) in cm. Only updated while in Loiter, RTL, Auto.
WPBrg Bearing to the next waypoint in degrees
PErX Distance to intermediate target between copter and the next waypoint in the latitude direction
PErY Distance to intermediate target between copter and the next waypoint in the longitude direction
DVelX Desired velocity in cm/s in the latitude direction
DVelY Desired velocity in cm/s in the longitude direction
VelX Actual accelerometer + gps velocity estimate in the latitude direction
VelY Actual accelerometer + gps velocity estimate in the longitude direction
DAcX Desired acceleration in cm/s/s in the latitude direction
DAcY Desired acceleration in cm/s/s in the longitude direction
DRol Desired roll angle in centi-degrees
DPit Desired pitch angle in centi-degrees

PM (performance monitoring):

NLon Number of long running main loops (i.e. loops that take more than 20% longer than they should according to SCHED_LOOP_RATE - ex. 3ms for 400Hz rate)
NLoop The total number of loops since the last PM message was displayed. This allows you to calculate the percentage of slow running loops (which should never be higher than 15%). Note that the value will depend on the autopilot clock speed
MaxT The maximum time that any loop took since the last PM message. This shouldn’t exceed 120% of scheduler loop period, but will be much higher during the interval where the motors are armed
Mem Available memory, in bytes
Load Percentage (times 10) of the scheduler loop period when CPU is used

RCOUT (pwm output to individual RC outputs):

RC1, RC2, etc : pwm command sent from autopilot to the esc/motor/RC output


When you download the dataflash log files from the autopilot it will automatically create a KMZ file (file with extension .kmz). This file can be opened with Google Earth (just double click the file) to view your flight in Google Earth. Please see the instructions on the Telemetry Logs Page for additional details.

Video tutorials