iNavFlight · mart1npetroff · May 13, 2026 · May 14, 2026 · May 14, 2026
diff --git a/docs/Navigation.md b/docs/Navigation.md
@@ -38,6 +38,100 @@ PID meaning:
 * POS - translated position error to desired velocity, uses P term only
 * POSR - translates velocity error to desired acceleration
 
+## Precision Landing Target Consumer (MSP)
+
+INAV can consume externally computed precision-landing target offsets over MSP.
+INAV only consumes target updates.
+
+### Build-time availability
+This feature is compiled only when `USE_PRECISION_LANDING` is enabled for the target.
+On flash-constrained targets, it can be excluded at build time to preserve headroom.
+
+### Core behavior
+* `nav_precision_landing` enables/disables this feature.
+* `MSP2_INAV_SET_PRECISION_LANDING_TARGET` updates a target cache and returns acceptance/use status.
+* Target updates do **not** arm/disarm, do **not** switch modes, and do **not** start LAND/POSHOLD by themselves.
+* Corrections are applied only when:
+  * active profile is MC/VTOL-hover-capable, and
+  * current navigation context is POSHOLD-compatible or LAND-compatible.
+* In fixed-wing profile, updates may be cached but are not used for correction.
+
+### Scope and limits
+Precision landing here is a **final alignment/correction layer**.
+It does not replace normal waypoint/home navigation and it does not solve high-speed approach planning by itself.
+
+Recommended VTOL flow:
+1. transition to MC / hover-capable control
+2. controlled low-speed arrival near landing zone
+3. precision target alignment in POSHOLD
+4. precision correction during LAND
+
+### Why not `SET_WP`?
+`SET_WP` is a navigation target command interface.
+Precision landing target updates are external measurement inputs with validity/confidence/age semantics and target-loss handling.
+
+This feature intentionally keeps those semantics bounded to MC POSHOLD/LAND correction, rather than repeatedly rewriting mission/waypoint targets.
+
+### POSHOLD behavior
+When a fresh/valid target exists, horizontal correction is applied to improve alignment above the target.
+Descent is not started automatically in POSHOLD.
+
+### LAND behavior
+When LAND is active and target data is fresh/valid, INAV applies horizontal correction through normal navigation controllers.
+Vertical descent profile remains the standard INAV LAND behavior (`nav_land_*` settings).
+If target is not available at LAND entry, normal landing behavior is used.
+
+### Lost target recovery
+If target is lost after precision correction already became active:
+1. HOLD (`nav_precision_landing_lost_hold_time_ms`)
+2. CLIMB_AND_RETRY (`nav_precision_landing_retry_altitude_cm`, `nav_precision_landing_retry_timeout_ms`)
+3. Repeat up to `nav_precision_landing_retry_count`
+4. Fallback to normal landing
+
+### Key settings
+You do not need to tune all settings on day 1. Start with the minimum set, then tune only if needed.
+
+Minimum required:
+* `nav_precision_landing`: Master enable.  
+  `OFF` keeps legacy behavior unchanged. `ON` allows precision-target consumption in MC/VTOL POSHOLD/LAND contexts.
+* `nav_precision_landing_source`: Target source selector (currently `MSP` only).  
+  Keep at `MSP`.
+* `nav_precision_landing_min_confidence`: Reject low-confidence target reports.  
+  Example: `60` accepts detections >= 60%; raising to `75` reduces false positives but may drop valid detections in poor light.
+* `nav_precision_landing_max_target_age_ms`: Freshness limit for cached targets.  
+  Example: at 20 Hz companion update rate (~50 ms period), `500` ms is tolerant; `200` ms is stricter and avoids stale corrections.
+
+Recommended for first field tests:
+* `nav_precision_landing_max_correction_speed_cm_s`: Horizontal correction clamp.  
+  Example: `80-120` cm/s is conservative for small/medium copters; higher values react faster but can look aggressive near touchdown.
+* `nav_precision_landing_align_radius_cm`: Radius treated as close-enough center reference for alignment quality checks.  
+  Example: `60-100` cm for MVP tests.
+
+Safety and fault-handling settings:
+* `nav_precision_landing_max_offset_cm`: Hard bound on accepted offset magnitude.  
+  Example: `1500` cm rejects obviously wrong detections. Set `0` to disable this check.
+* `nav_precision_landing_lost_hold_time_ms`: Time to hold after target loss before retry climb.  
+  Example: `1200-2000` ms to allow short vision dropouts to recover without immediate climb.
+* `nav_precision_landing_retry_count`: Number of retry attempts before fallback to normal landing.  
+  Example: `2` gives two climb/reacquire attempts.
+* `nav_precision_landing_retry_altitude_cm`: Climb distance per retry.  
+  Example: `150-300` cm can improve camera view/FOV.
+* `nav_precision_landing_retry_timeout_ms`: Max retry phase duration.  
+  `0` = AUTO mode, computed as `2 x nav_precision_landing_lost_hold_time_ms`.  
+  Example: with `lost_hold=1500`, AUTO timeout becomes `3000` ms.
+
+Suggested starter profile (conservative):
+* `nav_precision_landing = ON`
+* `nav_precision_landing_source = MSP`
+* `nav_precision_landing_min_confidence = 60`
+* `nav_precision_landing_max_target_age_ms = 500`
+* `nav_precision_landing_max_correction_speed_cm_s = 100`
+* `nav_precision_landing_align_radius_cm = 80`
+* `nav_precision_landing_lost_hold_time_ms = 1500`
+* `nav_precision_landing_retry_count = 2`
+* `nav_precision_landing_retry_altitude_cm = 200`
+* `nav_precision_landing_retry_timeout_ms = 0` (AUTO)
+
 ## NAV RTH - return to home mode
 
 Home for RTH is the position where vehicle was first armed. This position may be offset by the CLI settings `nav_rth_home_offset_distance` and `nav_rth_home_offset_direction`. This position may also be overridden with Safehomes. RTH requires accelerometer, compass and GPS sensors.

diff --git a/docs/Settings.md b/docs/Settings.md
@@ -4434,6 +4434,116 @@ If GPS fails wait for this much seconds before switching to emergency landing mo
 
 ---
 
+### nav_precision_landing
+
+Enable MSP-based precision landing target consumption. This does not trigger mode changes on its own.
+
+| Default | Min | Max |
+| --- | --- | --- |
+| OFF | OFF | ON |
+
+---
+
+### nav_precision_landing_align_radius_cm
+
+Horizontal radius considered close enough to center for precision-alignment quality checks [cm].
+
+| Default | Min | Max |
+| --- | --- | --- |
+| 80 | 10 | 2000 |
+
+---
+
+### nav_precision_landing_lost_hold_time_ms
+
+Hold duration after target loss before climb-and-retry starts [ms].
+
+| Default | Min | Max |
+| --- | --- | --- |
+| 1500 | 100 | 10000 |
+
+---
+
+### nav_precision_landing_max_correction_speed_cm_s
+
+Maximum horizontal correction speed generated from target offset [cm/s].
+
+| Default | Min | Max |
+| --- | --- | --- |
+| 100 | 10 | 1000 |
+
+---
+
+### nav_precision_landing_max_offset_cm
+
+Maximum allowed horizontal target offset magnitude. Larger offsets are rejected [cm]. Set 0 to disable this check.
+
+| Default | Min | Max |
+| --- | --- | --- |
+| 1500 | 0 | 5000 |
+
+---
+
+### nav_precision_landing_max_target_age_ms
+
+Maximum age of a cached precision target that can still be used [ms].
+
+| Default | Min | Max |
+| --- | --- | --- |
+| 500 | 50 | 5000 |
+
+---
+
+### nav_precision_landing_min_confidence
+
+Minimum confidence required to accept/use a precision landing target update [0..100].
+
+| Default | Min | Max |
+| --- | --- | --- |
+| 60 | 0 | 100 |
+
+---
+
+### nav_precision_landing_retry_altitude_cm
+
+Climb distance for each retry attempt after target loss [cm].
+
+| Default | Min | Max |
+| --- | --- | --- |
+| 200 | 50 | 2000 |
+
+---
+
+### nav_precision_landing_retry_count
+
+Maximum number of climb-and-retry attempts after target loss.
+
+| Default | Min | Max |
+| --- | --- | --- |
+| 2 | 0 | 10 |
+
+---
+
+### nav_precision_landing_retry_timeout_ms
+
+Timeout for each climb-and-retry phase [ms]. Set to 0 for AUTO mode (computed as 2 x nav_precision_landing_lost_hold_time_ms).
+
+| Default | Min | Max |
+| --- | --- | --- |
+| 0 | 0 | 60000 |
+
+---
+
+### nav_precision_landing_source
+
+Precision landing target source.
+
+| Allowed Values |  |
+| --- | --- |
+| MSP | Default |
+
+---
+
 ### nav_rth_abort_threshold
 
 RTH sanity checking feature will notice if distance to home is increasing during RTH and once amount of increase exceeds the threshold defined by this parameter, instead of continuing RTH machine will enter emergency landing, self-level and go down safely. Default is 500m which is safe enough for both multirotor machines and airplanes. Set to 0 to disable. [cm]

diff --git a/docs/development/msp/README.md b/docs/development/msp/README.md
@@ -449,6 +449,7 @@ When the MSP JSON specification changes, bump `msp_messages.json` version:
 [8731 - MSP2_INAV_NAV_TARGET](#msp2_inav_nav_target)  
 [8736 - MSP2_INAV_FULL_LOCAL_POSE](#msp2_inav_full_local_pose)  
 [8737 - MSP2_INAV_SET_WP_INDEX](#msp2_inav_set_wp_index)  
+[8753 - MSP2_INAV_SET_PRECISION_LANDING_TARGET](#msp2_inav_set_precision_landing_target)  
 [8739 - MSP2_INAV_SET_CRUISE_HEADING](#msp2_inav_set_cruise_heading)  
 [12288 - MSP2_BETAFLIGHT_BIND](#msp2_betaflight_bind)  
 [12289 - MSP2_RX_BIND](#msp2_rx_bind)  
@@ -4698,6 +4699,31 @@ When the MSP JSON specification changes, bump `msp_messages.json` version:
 
 **Notes:** Returns error if the aircraft is not armed, `NAV_WP_MODE` is not active, or the index is outside the valid mission range (`startWpIndex` to `startWpIndex + waypointCount - 1`). On success, sets `posControl.activeWaypointIndex` to the requested index and fires `NAV_FSM_EVENT_SWITCH_TO_WAYPOINT_JUMP`, transitioning the navigation FSM back to `NAV_STATE_WAYPOINT_PRE_ACTION` so the flight controller re-initialises navigation for the new target.
 
+## <a id="msp2_inav_set_precision_landing_target"></a>`MSP2_INAV_SET_PRECISION_LANDING_TARGET (8753 / 0x2231)`
+**Description:** Updates the external precision-landing target cache used by NAV precision landing. This message does not arm/disarm, does not switch flight modes, and does not start landing by itself.
+
+**Request Payload:**
+|Field|C Type|Size (Bytes)|Units|Description|
+|---|---|---|---|---|
+| `valid` | `uint8_t` | 1 | - | 0 clears/invalidates target, non-zero marks update as valid |
+| `confidence` | `uint8_t` | 1 | percent | External confidence [0..100] |
+| `frame` | `uint8_t` | 1 | enum | Target frame. Current implementation supports `0` = body FRD |
+| `offset_forward_cm` | `int16_t` | 2 | cm | Target offset forward from vehicle body origin |
+| `offset_right_cm` | `int16_t` | 2 | cm | Target offset right from vehicle body origin |
+| `distance_cm` | `uint16_t` | 2 | cm | Optional distance to target (`0` if unknown) |
+| `timestamp_ms` | `uint32_t` | 4 | ms | Optional companion timestamp (`0` allowed, informational/debug) |
+
+**Reply Payload:**
+|Field|C Type|Size (Bytes)|Description|
+|---|---|---|---|
+| `accepted` | `uint8_t` | 1 | Payload accepted into target-processing path |
+| `used_now` | `uint8_t` | 1 | Target is currently influencing navigation correction |
+| `nav_precision_state` | `uint8_t` | 1 | Internal precision-landing state |
+| `reason` | `uint8_t` | 1 | Result reason (`OK`, `NOT_ENABLED`, `LOW_CONFIDENCE`, `BAD_FRAME`, `STALE`, `OFFSET_TOO_LARGE`, `NOT_MC_PROFILE`, `NOT_IN_POSHOLD_OR_LAND`, etc.) |
+| `retry_count` | `uint8_t` | 1 | Active retry attempt count |
+
+**Notes:** Available only when firmware is built with `USE_PRECISION_LANDING`. Precision corrections are only applied in MC/VTOL-hover-capable profile and only in POSHOLD/LAND-compatible contexts. Outside those contexts, valid updates may still be cached (`used_now = 0`). Freshness is evaluated using FC receive time, not companion clock synchronization.
+
 ## <a id="msp2_inav_set_cruise_heading"></a>`MSP2_INAV_SET_CRUISE_HEADING (8739 / 0x2223)`
 **Description:** Sets the course heading target while Cruise or Course Hold mode is active, causing the aircraft to turn to and maintain the new heading.  
 
@@ -4735,4 +4761,3 @@ When the MSP JSON specification changes, bump `msp_messages.json` version:
 | `reserved_for_custom_use` | `uint8_t[3]` | 3 | Reserved for custom use |
 
 **Notes:** Requires a receiver using MSP as the protocol, sends MSP2_RX_BIND to the receiver.
-
diff --git a/docs/development/msp/msp_messages.json b/docs/development/msp/msp_messages.json
@@ -11260,6 +11260,92 @@
             "notes": "Returns error if the aircraft is not armed, `NAV_WP_MODE` is not active, or the index is outside the valid mission range (`startWpIndex` to `startWpIndex + waypointCount - 1`). On success, sets `posControl.activeWaypointIndex` to the requested index and fires `NAV_FSM_EVENT_SWITCH_TO_WAYPOINT_JUMP`, transitioning the navigation FSM back to `NAV_STATE_WAYPOINT_PRE_ACTION` so the flight controller re-initialises navigation for the new target.",
             "description": "Jumps to a specific waypoint during an active waypoint mission, causing the aircraft to immediately begin navigating toward the new target waypoint."
         },
+        "MSP2_INAV_SET_PRECISION_LANDING_TARGET": {
+            "code": 8753,
+            "mspv": 2,
+            "request": {
+                "payload": [
+                    {
+                        "name": "valid",
+                        "ctype": "uint8_t",
+                        "desc": "0 clears/invalidates target, non-zero marks update as valid.",
+                        "units": ""
+                    },
+                    {
+                        "name": "confidence",
+                        "ctype": "uint8_t",
+                        "desc": "External confidence value.",
+                        "units": "percent"
+                    },
+                    {
+                        "name": "frame",
+                        "ctype": "uint8_t",
+                        "desc": "Target coordinate frame; currently 0 = body FRD.",
+                        "units": "enum"
+                    },
+                    {
+                        "name": "offset_forward_cm",
+                        "ctype": "int16_t",
+                        "desc": "Target forward offset relative to vehicle body frame.",
+                        "units": "cm"
+                    },
+                    {
+                        "name": "offset_right_cm",
+                        "ctype": "int16_t",
+                        "desc": "Target right offset relative to vehicle body frame.",
+                        "units": "cm"
+                    },
+                    {
+                        "name": "distance_cm",
+                        "ctype": "uint16_t",
+                        "desc": "Optional distance to target (0 if unknown).",
+                        "units": "cm"
+                    },
+                    {
+                        "name": "timestamp_ms",
+                        "ctype": "uint32_t",
+                        "desc": "Optional companion timestamp (0 allowed, informational/debug).",
+                        "units": "ms"
+                    }
+                ]
+            },
+            "reply": {
+                "payload": [
+                    {
+                        "name": "accepted",
+                        "ctype": "uint8_t",
+                        "desc": "Payload accepted by precision-landing target consumer.",
+                        "units": ""
+                    },
+                    {
+                        "name": "used_now",
+                        "ctype": "uint8_t",
+                        "desc": "Target is currently influencing navigation correction.",
+                        "units": ""
+                    },
+                    {
+                        "name": "nav_precision_state",
+                        "ctype": "uint8_t",
+                        "desc": "Current internal precision-landing state.",
+                        "units": "enum"
+                    },
+                    {
+                        "name": "reason",
+                        "ctype": "uint8_t",
+                        "desc": "Processing reason/result code.",
+                        "units": "enum"
+                    },
+                    {
+                        "name": "retry_count",
+                        "ctype": "uint8_t",
+                        "desc": "Current retry counter value.",
+                        "units": ""
+                    }
+                ]
+            },
+            "notes": "This message updates precision-landing target cache only. It does not arm/disarm, does not switch modes, and does not trigger landing by itself. Available only when firmware is built with USE_PRECISION_LANDING. Precision correction is applied only in MC/VTOL hover-capable profile and POSHOLD/LAND-compatible navigation contexts. Target freshness is evaluated using FC receive time.",
+            "description": "Updates the external precision-landing target cache consumed by NAV precision landing."
+        },
         "MSP2_INAV_SET_CRUISE_HEADING": {
             "code": 8739,
             "mspv": 2,
@@ -11354,4 +11440,4 @@
             "description": "Initiates binding for MSP receivers (mLRS)."
         }
     }
-}
+}
diff --git a/src/main/CMakeLists.txt b/src/main/CMakeLists.txt
@@ -585,6 +585,8 @@ main_sources(COMMON_SRC
     navigation/navigation_fw_launch.c
     navigation/navigation_geo.c
     navigation/navigation_multicopter.c
+    navigation/precision_landing.c
+    navigation/precision_landing.h
     navigation/navigation_pos_estimator.c
     navigation/navigation_pos_estimator_private.h
     navigation/navigation_pos_estimator_agl.c