# APX4 2.7.37

## What's new

### GNSS denied operational enhancements <a href="#gnss-denied-operational-enhancements" id="gnss-denied-operational-enhancements"></a>

Added support for operator defined estimator position reset while dead-reckoning. See details at: <https://auterion.com/auterion-introduces-new-capabilities-for-efficient-isr-missions-in-gps-denied-conditions/>

### Fixed-wing performance modeling

New service ceiling parameter:

* `FW_S_CEILING` – defines the altitude MSL in standard atmosphere at which the vehicle can still achieve a climb rate of 0.5 m/s at trim airspeed and maximum throttle

New features:

* Compensate TECS minimum sink speed for weight ratio and air density
* Compensate TECS maximum climb speed for weight ratio and air density
* Compensate calibrated trim airspeed for increased load factor due to weight
* Compensate calibrated minimum airspeed for increased load factor due to weight

The weight ratio is calculated from parameters `WEIGHT_BASE` and `WEIGHT_GROSS`.

## What improved

General:

* Bugfix: prevent overflow in UTM global position
* Handle EKF height reset in terrain estimator
* Robustify RTK position fix
* Fix bug in INA238 driver which reset the shunt calibration on an incorrect readback
* Prevent MAVLink deadlock when calling ‘mavlink status’ via MAVLink shell.
* Fix erroneously aborting a mission landing when an RTL is triggered with home land approaches being available
* Prevent a deadlock in MAVLink transmission when using TX DMA on TELEM1
* Bugfix: only allow GNSS switching while the primary GNSS receiver is unavailable
* Bugfix: resolve corner case preventing Autotune start
* Enable use of ADS1115 with analog power modules on FMUv6x

Multicopter:

* Bugfix: ensure multicopter altitude changes are linear between two waypoints
* Improve land behavior when triggered while moving in Manual Position Mode

VTOL:

* Fix VTOL takeoff when home position does not coincide with takeoff position
* Battery estimation improvement: reset current filter when transitioning to fixed-wing flight
* Bugfix: disallow manual RTL trigger (immediate back-transition for VTOL) while already in mission RTL
* Limit VTOL tilt-rotor thrust compensation due to non-vertical motors in transition phases
* Avoid hard banking when overshooting land point during transition
* Bugfix: handle EKF height resets in quadchute logic
* Bugfix: refer only to `VT_ARSP_TRANS`, not `FW_AIRSPD_MIN`, for transition airspeed threshold
* Bugfix: disallow Takeoff Mode activation when VTOL takeoff is commanded while in-air