// @Description: This enables/disables the checking for three carriage returns on telemetry links on startup to enter the diagnostics command line interface
// @Description: Level of agressiveness for autotune. When autotune is run a lower AUTOTUNE_LEVEL will result in a 'softer' tune, with less agressive gains. For most users a level of 6 is recommended.
// @Description: This controls the amount of down pitch to add in FBWA and AUTOTUNE modes when at low throttle. No down trim is added when throttle is above TRIM_THROTTLE. Below TRIM_THROTTLE downtrim is added in proportion to the amount the throttle is below TRIM_THROTTLE. At zero throttle the full downpitch specified in this parameter is added. This parameter is meant to help keep airspeed up when flying in FBWA mode with low throttle, such as when on a landing approach, without relying on an airspeed sensor. A value of 2 degrees is good for many planes, although a higher value may be needed for high drag aircraft.
// @Description: This controls the minimum altitude change for a waypoint before a glide slope will be used instead of an immediate altitude change. The default value is 15 meters, which helps to smooth out waypoint missions where small altitude changes happen near waypoints. If you don't want glide slopes to be used in missions then you can set this to zero, which will disable glide slope calculations. Otherwise you can set it to a minimum number of meters of altitude error to the destination waypoint before a glide slope will be used to change altitude.
// @Description: When enabled, this adds user stick input to the control surfaces in auto modes, allowing the user to have some degree of flight control without changing modes. There are two types of stick mixing available. If you set STICK_MIXING to 1 then it will use "fly by wire" mixing, which controls the roll and pitch in the same way that the FBWA mode does. This is the safest option if you usually fly ArduPlane in FBWA or FBWB mode. If you set STICK_MIXING to 2 then it will enable direct mixing mode, which is what the STABILIZE mode uses. That will allow for much more extreme maneuvers while in AUTO mode.
// @Description: When enabled this tells the APM to skip the normal gyroscope calibration at startup, and instead use the saved gyro calibration from the last flight. You should only enable this if you are careful to check that your aircraft has good attitude control before flying, as some boards may have significantly different gyro calibration between boots, especially if the temperature changes a lot. If gyro calibration is skipped then APM relies on using the gyro drift detection code to get the right gyro calibration in the few minutes after it boots. This option is mostly useful where the requirement to hold the plane still while it is booting is a significant problem.
// @Description: When enabled this option gives FBWA navigation and steering in AUTO mode. This can be used to allow manual stabilised piloting with waypoint logic for triggering payloads. With this enabled the pilot has the same control over the plane as in FBWA mode, and the normal AUTO navigation is completely disabled. This option is not recommended for normal use.
// @Description: Minimum GPS ground speed in m/s used by the speed check that un-suppresses throttle in auto-takeoff. This can be be used for catapult launches where you want the motor to engage only after the plane leaves the catapult, but it is preferable to use the TKOFF_THR_MINACC and TKOFF_THR_DELAY parameters for catapult launches due to the errors associated with GPS measurements. For hand launches with a pusher prop it is strongly advised that this parameter be set to a value no less than 4 m/s to provide additional protection against premature motor start. Note that the GPS velocity will lag the real velocity by about 0.5 seconds. The ground speed check is delayed by the TKOFF_THR_DELAY parameter.
// @Description: Minimum forward acceleration in m/s/s before arming the ground speed check in auto-takeoff. This is meant to be used for hand launches. Setting this value to 0 disables the acceleration test which means the ground speed check will always be armed which could allow GPS velocity jumps to start the engine. For hand launches and bungee launches this should be set to around 15.
// @Description: This parameter sets the time delay (in 1/10ths of a second) that the ground speed check is delayed after the forward acceleration check controlled by TKOFF_THR_MINACC has passed. For hand launches with pusher propellers it is essential that this is set to a value of no less than 2 (0.2 seconds) to ensure that the aircraft is safely clear of the throwers arm before the motor can start. For bungee launches a larger value can be used (such as 30) to give time for the bungee to release from the aircraft before the motor is started.
// @Description: This parameter sets the amount of elevator to apply during the initial stage of a takeoff. It is used to hold the tail wheel of a taildragger on the ground during the initial takeoff stage to give maximum steering. This option should be conbined with the TKOFF_TDRAG_SPD1 option and the GROUND_STEER_ALT option along with tuning of the ground steering controller. A value of zero means to bypass the initial "tail hold" stage of takeoff. Set to zero for hand and catapult launch. For tail-draggers you should normally set this to 100, meaning full up elevator during the initial stage of takeoff. For most tricycle undercarriage aircraft a value of zero will work well, but for some tricycle aircraft a small negative value (say around -20 to -30) will apply down elevator which will hold the nose wheel firmly on the ground during initial acceleration. Only use a negative value if you find that the nosewheel doesn't grip well during takeoff. Too much down elevator on a tricycle undercarriage may cause instability in steering as the plane pivots around the nosewheel. Add down elevator 10 percent at a time.
// @Description: This parameter sets the airspeed at which to stop holding the tail down and transition to rudder control of steering on the ground. When TKOFF_TDRAG_SPD1 is reached the pitch of the aircraft will be held level until TKOFF_ROTATE_SPD is reached, at which point the takeoff pitch specified in the mission will be used to "rotate" the pitch for takeoff climb. Set TKOFF_TDRAG_SPD1 to zero to go straight to rotation. This should be set to zero for hand launch and catapult launch. It should also be set to zero for tricycle undercarriages. For tail dragger aircraft it should be set just below the stall speed.
// @Description: This parameter sets the airspeed at which the aircraft will "rotate", setting climb pitch specified in the mission. If TKOFF_ROTATE_SPD is zero then the climb pitch will be used as soon as takeoff is started. For hand launch and catapult launches a TKOFF_ROTATE_SPD of zero should be set. For all ground launches TKOFF_ROTATE_SPD should be set above the stall speed, usually by about 10 to 30 percent
// @Description: This parameter sets the slew rate for the throttle during auto takeoff. When this is zero the THR_SLEWRATE parameter is used during takeoff. For rolling takeoffs it can be a good idea to set a lower slewrate for takeoff to give a slower acceleration which can improve ground steering control. The value is a percentage throttle change per second, so a value of 20 means to advance the throttle over 5 seconds on takeoff. Values below 20 are not recommended as they may cause the plane to try to climb out with too little throttle.
// @Description: This is a RC input channel which when it goes above 1700 enables FBWA taildragger takeoff mode. It should be assigned to a momentary switch. Once this feature is enabled it will stay enabled until the aircraft goes above TKOFF_TDRAG_SPD1 airspeed, changes mode, or the pitch goes above the initial pitch when this is engaged or goes below 0 pitch. When enabled the elevator will be forced to TKOFF_TDRAG_ELEV. This option allows for easier takeoffs on taildraggers in FBWA mode, and also makes it easier to test auto-takeoff steering handling in FBWA. Setting it to 0 disables this option.
// @Description: This controls the maximum bank angle in degrees during flight modes where level flight is desired, such as in the final stages of landing, and during auto takeoff. This should be a small angle (such as 5 degrees) to prevent a wing hitting the runway during takeoff or landing. Setting this to zero will completely disable heading hold on auto takeoff and final landing approach.
// @Description: Used in autoland to give the minimum pitch in the final stage of landing (after the flare). This parameter can be used to ensure that the final landing attitude is appropriate for the type of undercarriage on the aircraft. Note that it is a minimum pitch only - the landing code will control pitch above this value to try to achieve the configured landing sink rate.
// @Description: Altitude in autoland at which to lock heading and flare to the LAND_PITCH_CD pitch. Note that this option is secondary to LAND_FLARE_SEC. For a good landing it preferable that the flare is triggered by LAND_FLARE_SEC.
// @Description: Vertical time before landing point at which to lock heading and flare with the motor stopped. This is vertical time, and is calculated based solely on the current height above the ground and the current descent rate.
// @Description: Which navigation controller to enable. Currently the only navigation controller available is L1. From time to time other experimental conrtrollers will be added which are selected using this parameter.
// @Description: The percent of mixing between GPS altitude and baro altitude. 0 = 100% gps, 1 = 100% baro. It is highly recommend that you not change this from the default of 1, as GPS altitude is notoriously unreliable. The only time I would recommend changing this is if you have a high altitude enabled GPS, and you are dropping a plane from a high altitude baloon many kilometers off the ground.
// @Description: This sets what algorithm will be used for altitude control. The default is zero, which selects the most appropriate algorithm for your airframe. Currently the default is to use TECS (total energy control system). From time to time we will add other experimental altitude control algorithms which will be seleted using this parameter.
// @Description: Defines the maximum distance from a waypoint that when crossed indicates the waypoint may be complete. To avoid the aircraft looping around the waypoint in case it misses by more than the WP_RADIUS an additional check is made to see if the aircraft has crossed a "finish line" passing through the waypoint and perpendicular to the flight path from the previous waypoint. If that finish line is crossed then the waypoint is considered complete. Note that the navigation controller may decide to turn later than WP_RADIUS before a waypoint, based on how sharp the turn is and the speed of the aircraft. It is safe to set WP_RADIUS much larger than the usual turn radius of your aircaft and the navigation controller will work out when to turn. If you set WP_RADIUS too small then you will tend to overshoot the turns.
// @Description: Sets the maximum distance to a waypoint for the waypoint to be considered complete. This overrides the "cross the finish line" logic that is normally used to consider a waypoint complete. For normal AUTO behaviour this parameter should be set to zero. Using a non-zero value is only recommended when it is critical that the aircraft does approach within the given radius, and should loop around until it has done so. This can cause the aircraft to loop forever if its turn radius is greater than the maximum radius set.
// @Description: Defines the distance from the waypoint center, the plane will maintain during a loiter. If you set this value to a negative number then the default loiter direction will be counter-clockwise instead of clockwise.
// @Description: What to do on fence breach. If this is set to 0 then no action is taken, and geofencing is disabled. If this is set to 1 then the plane will enter GUIDED mode, with the target waypoint as the fence return point. If this is set to 2 then the fence breach is reported to the ground station, but no other action is taken. If set to 3 then the plane enters guided mode but the pilot retains manual throttle control.
// @Description: Altitude the aircraft will transit to when a fence breach occurs. If FENCE_RETALT is <= 0 then the midpoint between FENCE_MAXALT and FENCE_MINALT is used, unless FENCE_MAXALT < FENCE_MINALT. If FENCE_MAXALT < FENCE_MINALT AND FENCE_RETALT is <= 0 then ALT_HOLD_RTL is the altitude used on a fence breach.
// @Description: When set to 1, gefence automatically enables after an auto takeoff and automatically disables at the beginning of an auto landing. When on the ground before takeoff the fence is disabled. It is highly recommended to not use this option for line of sight flying and use a fence enable channel instead.
// @Description: When set to 1: on fence breach the plane will return to the nearest rally point rather than the fence return point. If no rally points have been defined the plane will return to the home point.
// @Description: This controls the use of stall prevention techniques, including roll limits at low speed and raising the minimum airspeed in turns. The limits are based on the aerodynamic load factor of a banked turn. This option relies on the correct ARSPD_FBW_MIN value being set correctly. Note that if you don't have an airspeed sensor then stall prevention will use an airspeed estimate based on the ground speed plus a wind estimate taken from the response of the autopilot banked turns. That synthetic airspeed estimate may be inaccurate, so you should not assume that stall prevention with no airspeed sensor will be effective.
// @Description: This is the minimum airspeed you want to fly at in modes where the autopilot controls the airspeed. This should be set to a value around 20% higher than the level flight stall speed for the airframe. This value is also used in the STALL_PREVENTION code.
// @Description: This is the maximum airspeed that you want to allow for your airframe in auto-throttle modes. You should ensure that this value is sufficiently above the ARSPD_FBW_MIN value to allow for a sufficient flight envelope to accurately control altitude using airspeed. A value at least 50% above ARSPD_FBW_MIN is recommended.
// @Description: Reverse sense of elevator in FBWB and CRUISE modes. When set to 0 up elevator (pulling back on the stick) means to lower altitude. When set to 1, up elevator means to raise altitude.
// @Description: This enables terrain following for CRUISE mode, FBWB mode, RTL and for rally points. To use this option you also need to set TERRAIN_ENABLE to 1, which enables terrain data fetching from the GCS, and you need to have a GCS that supports sending terrain data to the aircraft. When terrain following is enabled then CRUISE and FBWB mode will hold height above terrain rather than height above home. In RTL the return to launch altitude will be considered to be a height above the terrain. Rally point altitudes will be taken as height above the terrain. This option does not affect mission items, which have a per-waypoint flag for whether they are height above home or height above the terrain. To use terrain following missions you need a ground station which can set the waypoint type to be a terrain height waypoint when creating the mission.
// @Description: This controls how far ahead the terrain following code looks to ensure it stays above upcoming terrain. A value of zero means no lookahead, so the controller will track only the terrain directly below the aircraft. The lookahead will never extend beyond the next waypoint when in AUTO mode.
// @Description: This sets the rate in m/s at which FBWB and CRUISE modes will change its target altitude for full elevator deflection. Note that the actual climb rate of the aircraft can be lower than this, depending on your airspeed and throttle control settings. If you have this parameter set to the default value of 2.0, then holding the elevator at maximum deflection for 10 seconds would change the target altitude by 20 meters.
// @Description: The minimum throttle setting (as a percentage) which the autopilot will apply. For the final stage of an automatic landing this is always zero.
// @Description: maximum percentage change in throttle per second. A setting of 10 means to not change the throttle by more than 10% of the full throttle range in one second.
// @Description: maximum percentage change in flap output per second. A setting of 25 means to not change the flap by more than 25% of the full flap range in one second. A value of 0 means no rate limiting.
// @Description: When throttle is supressed in auto mode it is normally forced to zero. If you enable this option, then while suppressed it will be manual throttle. This is useful on petrol engines to hold the idle throttle manually while waiting for takeoff
// @Description: If this is set then when in STABILIZE, FBWA or ACRO modes the throttle is a direct passthru from the transmitter. This means the THR_MIN and THR_MAX settings are not used in these modes. This is useful for petrol engines where you setup a throttle cut switch that suppresses the throttle below the normal minimum.
// @Description: When enabled, this uses the throttle input in auto-throttle modes to 'nudge' the throttle or airspeed to higher or lower values. When you have an airspeed sensor the nudge affects the target airspeed, so that throttle inputs above 50% will increase the target airspeed from TRIM_ARSPD_CM up to a maximum of ARSPD_FBW_MAX. When no airspeed sensor is enabled the throttle nudge will push up the target throttle for throttle inputs above 50%.
// @Description: The action to take on a short (FS_SHORT_TIMEOUT) failsafe event. A short failsafe even can be triggered either by loss of RC control (see THR_FS_VALUE) or by loss of GCS control (see FS_GCS_ENABL). A short failsafe event in stabilization and manual modes will cause an change to CIRCLE mode if FS_SHORT_ACTN is 0 or 1, and a change to FBWA mode if FS_SHORT_ACTN is 2. In all other modes (including AUTO and GUIDED mode) a short failsafe event will cause no mode change is FS_SHORT_ACTN is set to 0, will cause a change to CIRCLE mode if set to 1 and will change to FBWA mode if set to 2. Please see the documentation for FS_LONG_ACTN for the behaviour after FS_LONG_TIMEOUT seconds of failsafe.
// @Description: The action to take on a long (FS_LONG_TIMEOUT seconds) failsafe event. If the aircraft was in a stabilization or manual mode when failsafe started and a long failsafe occurs then it will change to RTL mode if FS_LONG_ACTN is 0 or 1, and will change to FBWA if FS_LONG_ACTN is set to 2. If the aircraft was in an auto mode (such as AUTO or GUIDED) when the failsafe started then it will continue in the auto mode if FS_LONG_ACTN is set to 0, will change to RTL mode if FS_LONG_ACTN is set to 1 and will change to FBWA mode if FS_LONG_ACTN is set to 2.
// @Description: Battery voltage to trigger failsafe. Set to 0 to disable battery voltage failsafe. If the battery voltage drops below this voltage continuously for 10 seconds then the plane will switch to RTL mode
// @Description: Battery capacity remaining to trigger failsafe. Set to 0 to disable battery remaining failsafe. If the battery remaining drops below this level then the plane will switch to RTL mode immediately
// @Description: Enable ground control station telemetry failsafe. Failsafe will trigger after FS_LONG_TIMEOUT seconds of no MAVLink heartbeat messages. There are two possible enabled settings. Seeing FS_GCS_ENABL to 1 means that GCS failsafe will be triggered when the aircraft has not received a MAVLink HEARTBEAT message. Setting FS_GCS_ENABL to 2 means that GCS failsafe will be triggerded on either a loss of HEARTBEAT messages, or a RADIO_STATUS message from a MAVLink enabled 3DR radio indicating that the ground station is not receiving status updates from the aircraft, which is indicated by the RADIO_STATUS.remrssi field being zero (this may happen if you have a one way link due to asymmetric noise on the ground station and aircraft radios). WARNING: Enabling this option opens up the possibility of your plane going into failsafe mode and running the motor on the ground it it loses contact with your ground station. If this option is enabled on an electric plane then you should enable ARMING_REQUIRED.
// @Description: Altitude at which to use the ground steering controller on the rudder. If non-zero then the STEER2SRV controller will be used to control the rudder for altitudes within this limit of the home altitude.
// @Units: Meters
// @Range: -100 100
// @Increment: 0.1
// @User: Standard
GSCALAR(ground_steer_alt, "GROUND_STEER_ALT", 0),
// @Param: GROUND_STEER_DPS
// @DisplayName: Ground steer rate
// @Description: Ground steering rate in degrees per second for full rudder stick deflection
// @Description: Set RC trim PWM levels to current levels when switching away from manual mode. When this option is enabled and you change from MANUAL to any other mode then the APM will take the current position of the control sticks as the trim values for aileron, elevator and rudder. It will use those to set RC1_TRIM, RC2_TRIM and RC4_TRIM. This option is disabled by default as if a pilot is not aware of this option and changes from MANUAL to another mode while control inputs are not centered then the trim could be changed to a dangerously bad value. You can enable this option to assist with trimming your plane, by enabling it before takeoff then switching briefly to MANUAL in flight, and seeing how the plane reacts. You can then switch back to FBWA, trim the surfaces then again test MANUAL mode. Each time you switch from MANUAL the APM will take your control inputs as the new trim. After you have good trim on your aircraft you can disable TRIM_AUTO for future flights.
// @Description: This enables an older form of elevon mixing which is now deprecated. Please see the ELEVON_OUTPUT option for setting up elevons. The ELEVON_MIXING option should be set to 0 for elevon planes except for backwards compatibilty with older setups.
// @Description: Enable VTail output in software. If enabled then the APM will provide software VTail mixing on the elevator and rudder channels. There are 4 different mixing modes available, which refer to the 4 ways the elevator can be mapped to the two VTail servos. Note that you must not use VTail output mixing with hardware pass-through of RC values, such as with channel 8 manual control on an APM1. So if you use an APM1 then set FLTMODE_CH to something other than 8 before you enable VTAIL_OUTPUT. Please also see the MIXING_GAIN parameter for the output gain of the mixer.
// @Description: Enable software elevon output mixer. If enabled then the APM will provide software elevon mixing on the aileron and elevator channels. There are 4 different mixing modes available, which refer to the 4 ways the elevator can be mapped to the two elevon servos. Note that you must not use elevon output mixing with hardware pass-through of RC values, such as with channel 8 manual control on an APM1. So if you use an APM1 then set FLTMODE_CH to something other than 8 before you enable ELEVON_OUTPUT. Please also see the MIXING_GAIN parameter for the output gain of the mixer.
// @Description: The gain for the Vtail and elevon output mixers. The default is 0.5, which ensures that the mixer doesn't saturate, allowing both input channels to go to extremes while retaining control over the output. Hardware mixers often have a 1.0 gain, which gives more servo throw, but can saturate. If you don't have enough throw on your servos with VTAIL_OUTPUT or ELEVON_OUTPUT enabled then you can raise the gain using MIXING_GAIN. The mixer allows outputs in the range 900 to 2100 microseconds.
// @Description: Bitmap of what log types to enable in dataflash. This values is made up of the sum of each of the log types you want to be saved on dataflash. On a PX4 or Pixhawk the large storage size of a microSD card means it is usually best just to enable all log types by setting this to 65535. On APM2 the smaller 4 MByte dataflash means you need to be more selective in your logging or you may run out of log space while flying (in which case it will wrap and overwrite the start of the log). The individual bits are ATTITUDE_FAST=1, ATTITUDE_MEDIUM=2, GPS=4, PerformanceMonitoring=8, ControlTuning=16, NavigationTuning=32, Mode=64, IMU=128, Commands=256, Battery=512, Compass=1024, TECS=2048, Camera=4096, RCandServo=8192, Sonar=16384, Arming=32768, LogWhenDisarmed=65536
// @Description: RC channel to use to reset the mission to the first waypoint. When this channel goes above 1750 the mission is reset. Set RST_MISSION_CH to 0 to disable.
// @Description: offset to add to pitch - used for in-flight pitch trimming. It is recommended that instead of using this parameter you level your plane correctly on the ground for good flight attitude.
// @Description: Return to launch target altitude. This is the altitude the plane will aim for and loiter at when returning home. If this is negative (usually -1) then the plane will use the current altitude at the time of entering RTL. Note that when transiting to a Rally Point the alitude of the Rally Point is used instead of ALT_HOLD_RTL.
// @Description: This is the minimum altitude in centimeters that FBWB and CRUISE modes will allow. If you attempt to descend below this altitude then the plane will level off. A value of zero means no limit.
// @Description: Setting this to Enabled(1) will enable the compass. Setting this to Disabled(0) will disable the compass. Note that this is separate from COMPASS_USE. This will enable the low level senor, and will enable logging of magnetometer data. To use the compass for navigation you must also set COMPASS_USE to 1.
// @Description: An RC input channel to use for flaps control. If this is set to a RC channel number then that channel will be used for manual flaps control. When enabled, the percentage of flaps is taken as the percentage travel from the TRIM value of the channel to the MIN value of the channel. A value above the TRIM values will give inverse flaps (spoilers). This option needs to be enabled in conjunction with a FUNCTION setting on an output channel to one of the flap functions. When a FLAP_IN_CHANNEL is combined with auto-flaps the higher of the two flap percentages is taken. You must also enable a FLAPERON_OUTPUT flaperon mixer setting if using flaperons.
// @Description: Enable flaperon output in software. If enabled then the APM will provide software flaperon mixing on the FLAPERON1 and FLAPERON2 output channels specified using the FUNCTION on two auxillary channels. There are 4 different mixing modes available, which refer to the 4 ways the flap and aileron outputs can be mapped to the two flaperon servos. Note that you must not use flaperon output mixing with hardware pass-through of RC values, such as with channel 8 manual control on an APM1. So if you use an APM1 then set FLTMODE_CH to something other than 8 before you enable FLAPERON_OUTPUT. Please also see the MIXING_GAIN parameter for the output gain of the mixer. FLAPERON_OUTPUT cannot be combined with ELEVON_OUTPUT or ELEVON_MIXING.
// @Description: The speed in meters per second at which to engage FLAP_1_PERCENT of flaps. Note that FLAP_1_SPEED should be greater than or equal to FLAP_2_SPEED
// @Description: The speed in meters per second at which to engage FLAP_2_PERCENT of flaps. Note that FLAP_1_SPEED should be greater than or equal to FLAP_2_SPEED
// @Description: If set to a non-zero value then this is an RC input channel number to use for testing manual control in case the main FMU microcontroller on a PX4 or Pixhawk fails. When this RC input channel goes above 1750 the FMU will stop sending servo controls to the PX4IO board, which will trigger the PX4IO board to start using its failsafe override behaviour, which should give you manual control of the aircraft. That allows you to test for correct manual behaviour without actually crashing the FMU. This parameter is normally only set to a non-zero value for ground testing purposes. When the override channel is used it also forces the PX4 safety switch into an armed state. This allows it to be used as a way to re-arm a plane after an in-flight reboot. Use in that way is considered a developer option, for people testing unstable developer code. Note that you may set OVERRIDE_CHAN to the same channel as FLTMODE_CH to get PX4IO based override when in flight mode 6. Note that when override is triggered the 6 auxillary output channels on Pixhawk will no longer be updated, so all the flight controls you need must be assigned to the first 8 channels.
// @Description: A RC input channel number to enable inverted flight. If this is non-zero then the APM will monitor the correcponding RC input channel and will enable inverted flight when the channel goes above 1750.
// @Description: This controls whether real servo controls are used in HIL mode. If you enable this then the APM will control the real servos in HIL mode. If disabled it will report servo values, but will not output to the real servos. Be careful that your motor and propeller are not connected if you enable this option.
// @DisplayName: Limit of error in HIL attitude before reset
// @Description: This controls the maximum error in degrees on any axis before HIL will reset the DCM attitude to match the HIL_STATE attitude. This limit will prevent poor timing on HIL from causing a major attitude error. If the value is zero then no limit applies.
// @Description: Automatically begin landing sequence after arriving at RTL location. This requires the addition of a DO_LAND_START mission item, which acts as a marker for the start of a landing sequence. The closest landing sequence will be chosen to the current location.
// @Description: Automatically set roll/pitch trim from Tx at ground start. This makes the assumption that the RC transmitter has not been altered since trims were last captured.
// @Description: This enables the use of a rangefinder for automatic landing. The rangefinder will be used both on the landing approach and for final flare
