‘Collision Avoidance by Discussion’ (see this Journal, p. 159) has been part of the radar controversy since it began. If it is assumed, as I think it must be, that no solution is acceptable which does not apply to multilateral situations, the complications inherent in such a proposal become apparent. A bilateral agreement, for example, on alterations of course will be based on the situation as seen at a given moment; this may change drastically within minutes as other ships' bilateral or monolateral decisions are put into effect. These may necessitate changes in intention and further confabulation, possibly now with others than the ship originally contacted, and so on.