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# DetectAndAvoidMostUrgent (UORB message)

Detect-and-avoid summary for the most urgent active conflict.

Aggregated DAA status from navigator's `DetectAndAvoid` component.
It publishes the single active conflict that currently has the highest urgency
after the per-traffic conflict buffer has been updated.

Unlike `detect_and_avoid`, this topic is not published for every processed
traffic report and does not include the detailed horizontal and vertical geometry.
It is the topic used for overall DAA status, automatic-action decisions, and
prearm checks.

Published by: `navigator` (`DetectAndAvoid`)
Used by: `commander` DAA arming checks, logging, and tests

**TOPICS:** detect_and_avoid_most_urgent

## Fields

| Name                                                  | Type      | Unit [Frame] | Range/Enum | Description                                                                                                                                              |
| ----------------------------------------------------- | --------- | ------------ | ---------- | -------------------------------------------------------------------------------------------------------------------------------------------------------- |
| <a id="fld_timestamp"></a>timestamp                   | `uint64`  | us           |            | Time since system start                                                                                                                                  |
| <a id="fld_unique_id"></a>unique_id                   | `uint64`  |              |            | Encoded identifier of the current most urgent traffic aircraft, selected in priority order: ICAO address, ADS-B callsign, then reduced UAS ID tail bytes |
| <a id="fld_unique_id_encoding"></a>unique_id_encoding | `uint8`   |              |            | Namespace used to decode `unique_id`                                                                                                                     |
| <a id="fld_has_action"></a>has_action                 | `bool`    |              |            | True if the configured DAA response for this most urgent conflict is stronger than Warn only                                                             |
| <a id="fld_conflict_level"></a>conflict_level         | `uint8`   |              |            | Conflict level of the current most urgent active conflict                                                                                                |
| <a id="fld_aircraft_dist"></a>aircraft_dist           | `float32` | m            |            | Approximate 3D range to the most urgent traffic aircraft (9999 when empty)                                                                               |

## Constants

| Name                                                                            | Type    | Value | Description                                                   |
| ------------------------------------------------------------------------------- | ------- | ----- | ------------------------------------------------------------- |
| <a id="#UNIQUE_ID_ENCODING_ICAO"></a> UNIQUE_ID_ENCODING_ICAO                   | `uint8` | 0     | `unique_id` contains an ICAO address                          |
| <a id="#UNIQUE_ID_ENCODING_ADSB_CALLSIGN"></a> UNIQUE_ID_ENCODING_ADSB_CALLSIGN | `uint8` | 1     | `unique_id` contains an ADS-B callsign packed into a `uint64` |
| <a id="#UNIQUE_ID_ENCODING_UAS_ID"></a> UNIQUE_ID_ENCODING_UAS_ID               | `uint8` | 2     | `unique_id` contains the reduced tail bytes of a UAS ID       |

## Source Message

[Source file (GitHub)](https://github.com/PX4/PX4-Autopilot/blob/main/msg/DetectAndAvoidMostUrgent.msg)

::: details Click here to see original file

```c
# Detect-and-avoid summary for the most urgent active conflict.
#
# Aggregated DAA status from navigator's `DetectAndAvoid` component.
# It publishes the single active conflict that currently has the highest urgency
# after the per-traffic conflict buffer has been updated.
#
# Unlike `detect_and_avoid`, this topic is not published for every processed
# traffic report and does not include the detailed horizontal and vertical geometry.
# It is the topic used for overall DAA status, automatic-action decisions, and
# prearm checks.
#
# Published by: `navigator` (`DetectAndAvoid`)
# Used by: `commander` DAA arming checks, logging, and tests

uint8 UNIQUE_ID_ENCODING_ICAO = 0 # `unique_id` contains an ICAO address
uint8 UNIQUE_ID_ENCODING_ADSB_CALLSIGN = 1 # `unique_id` contains an ADS-B callsign packed into a `uint64`
uint8 UNIQUE_ID_ENCODING_UAS_ID = 2 # `unique_id` contains the reduced tail bytes of a UAS ID

uint64 timestamp # [us] Time since system start
uint64 unique_id # [-] Encoded identifier of the current most urgent traffic aircraft, selected in priority order: ICAO address, ADS-B callsign, then reduced UAS ID tail bytes
uint8 unique_id_encoding # [-] Namespace used to decode `unique_id`

bool has_action # [-] True if the configured DAA response for this most urgent conflict is stronger than Warn only
uint8 conflict_level # [-] Conflict level of the current most urgent active conflict
float32 aircraft_dist # [m] Approximate 3D range to the most urgent traffic aircraft (9999 when empty)
```

:::