EVLOS (Extended Visual Line of Sight) is an RPA operational concept that extends the remote pilot’s situational awareness beyond their own direct sight by using one or more trained Visual Observers stationed at strategic positions. The pilot retains full command of the aircraft, while observers relay real-time position and hazard information to maintain safe separation from other aircraft, people, and obstacles.
Definition #
Under Australian aviation regulations, EVLOS is defined as a type of operation where the remote pilot cannot maintain continuous unaided visual contact with the RPA, but uses trained observer(s) to extend effective visual coverage. It sits between standard VLOS operations and fully BVLOS (Beyond Visual Line of Sight) operations in terms of regulatory complexity and risk profile.
How EVLOS Works #
In an EVLOS operation, a chain of communication is established between the remote pilot and one or more Visual Observers (VOs). Each observer maintains direct visual contact with the RPA within their segment and communicates continuously with the pilot — typically via radio or intercom. Key requirements include:
- All observers must be trained and briefed prior to the operation
- Clear and reliable communication must exist between the pilot and every observer at all times
- The total operational area must be pre-surveyed and hazards identified
- The pilot retains final authority over the aircraft at all times
Regulatory Framework in Australia #
EVLOS operations in Australia fall under the Civil Aviation Safety Regulations (CASR) Part 101 and the associated Manual of Standards. Operators conducting EVLOS must hold a valid ReOC (Remote Operator’s Certificate) issued by CASA, and the remote pilot must hold a RePL (Remote Pilot Licence) with appropriate endorsements for the operation type.
CASA requires that EVLOS operations be explicitly addressed in the operator’s Operations Manual and that all observers are identified in the crew manifest and briefed under a formal pre-flight safety process. EVLOS is not permitted under the standard Excluded Category (sub-2kg) rules — it requires a certified operator framework.
EVLOS vs. VLOS vs. BVLOS #
It is important to understand the distinction between these three operational categories:
- VLOS — The pilot maintains continuous unaided visual contact with the RPA throughout the flight.
- EVLOS — Visual contact is extended through observers; the pilot cannot directly see the aircraft at all times but the aircraft remains within the visual coverage of the combined crew.
- BVLOS — The aircraft operates beyond the visual range of the entire crew. This requires the highest level of regulatory approval from CASA.
Practical Applications #
EVLOS is commonly used in industries where operations need to cover larger areas than standard VLOS permits, but where full BVLOS approval is not yet achievable. Typical applications in Australia include:
- Infrastructure inspection along pipelines, powerlines, or rail corridors
- Agricultural monitoring across large crop areas or stations
- Search and rescue support in coordination with emergency services
- Survey and mapping operations in remote or regional areas
Implications for Operators #
Any operator considering EVLOS operations should review CASA’s current guidance documents and ensure their Operations Manual specifically addresses the EVLOS methodology. Observer training and communication protocols must be documented and tested before any operational flight. Given the higher complexity compared to standard VLOS, operators should seek formal advice from a CASA-approved aviation safety consultant if they are new to EVLOS procedures.
Always verify current regulations directly with CASA before conducting any EVLOS operations. Regulatory requirements can change, and CASA publishes updated guidance on its website at casa.gov.au.