Article 41 of Additional Protocol I prohibits attacks against persons who are recognized, or who in the circumstances should be recognized, as hors de combat, including persons who clearly express an intention to surrender. Article 57 further requires those who plan or decide upon an attack to do everything feasible to verify that attack remains lawful. While these obligations have existed since 1977, autonomous and semi-autonomous systems operating at machine speed create a practical problem: no commonly specified machine-readable form exists through which an intention to surrender can be communicated and recognized by such systems.
This paper presents HF SIGNAL 01, a candidate surrender-recognition protocol combining a pulsating white optical signal and a radio-frequency signature, intended as a technical referent for machine-readable expressions of surrender. The paper does not claim operational effectiveness, adoption, or legal status. Instead, it evaluates the proposal against previously defined feasibility criteria for lawful operational safeguards, including technology readiness, latency, annotated datasets, and independent validation.
The assessment is deliberately conservative. HF SIGNAL 01 currently exists as a fully specified and publicly documented concept without experimental validation, implementation, or performance data. Its present contribution is documentary rather than operational. The paper argues that the existence of a publicly available and integrity-protected candidate standard changes the factual context in which surrender-recognition capabilities may be assessed, transforming what was previously described solely as technical impossibility into a documented question of design choice, review, and validation.
The paper concludes by inviting independent technical testing, dataset development, and examination within relevant international humanitarian law and autonomous weapons governance fora.
HF SIGNAL 01 is a recognition signal with channels matched to who is emitting it. Its primary channel requires no technology at all:
• The flag — a white circle on a red field, raised or displayed by the unarmed human. Like the white flag, it can be produced by anyone, anywhere, with cloth and paint — but it is specified for machine readability.
• Optical channel — 7 Hz pulsating white light, for equipped operators (vehicles, facilities, teams)
• Electronic channel — 144.0 MHz continuous FM tone, for equipped operators
Same protocol, same meaning, different levels of access: bare hands or instruments. No one is excluded from the possibility of signalling — this is the humanitarian point. A surrender signal that requires equipment contradicts itself: the person surrendering is, by definition, the one who has laid everything down. This is why the primary channel is cloth and paint. The published technical specification documents the optical and radio channels; the flag is the human-side channel of the same architecture.
International Humanitarian Law · Autonomous Weapons Systems · Lethal Weapons Systems · Article 41 · Article 57 · Surrender Recognition · Machine-Readable Signal
HF SIGNAL 01 applies the feasibility criteria developed in: Lawful Operational Safeguards in AI Systems (Paper I) and Systemic Arrestability (Paper II).