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Sense and avoid (S&A) corresponds to the piloting principle “see and avoid” used in all air space volumes where the pilot is responsible for ensuring separation from nearby aircraft, terrain, and obstacles (e.g. weather). To determine appropriate spectrum requirements related to the S&A function, two aspects must be considered:

Firstly, all the RF equipment designed to collect raw data related to the “sense” function will have specific requirements depending on the ITU-R services involved. For example, the evaluation of the close proximity of the UA using radar equipment will operate in radio determination service bands. It should be studied if this functionality can be developed by using existing systems such as radar, ACAS, ADS-B, and UAT. The data derived by the sensors could either directly be processed inside the UA or be transmitted to the UACS.

Secondly, the control of the proper operation of this S&A function will be permanently or regularly checked at the UACS. If necessary, S&A parameters may be modified by the UACS, depending upon the area of flight, the weather conditions, or the level of autonomy assigned to the UA. In these bi-directional communications between the UACS and the UA for the S&A function, two different information streams must be considered:

The S&A data uplink will allow the UACS to control the operation of this function according to the conditions of the flight. Identical to the Control uplink, it is expected that such communication will not require high bit rates.

The S&A data downlink from the UA to the UACS indicates that the S&A function operates as desired. Similar to the Control downlink requirement, the need to send video streams under this S&A function must be considered avoiding duplication between Command and Control and S&A video downlinks.

Similar to the command and control considerations, it is expected that the “S&A data” RF communication requirements will have to be compliant with future ICAO standards for the safe flight of the UA in areas under the responsibility of the aviation authorities.