Not surprisingly much of the work that has been done on collision at sea has involved the study of collisions which have actually occurred. There must however be a wealth of untapped data relating to ‘near misses’ judging by the hair-raising stories often told by ships' officers. These accounts, sometimes of ships passing one another so closely in fog that human sounds have been heard, are doubtless subject to embellishment but are, nevertheless, the stuff that nightmares are made of.

An interesting point which (perhaps predictably) features in many such stories is that the navigator presents himself as a victim of circumstances rather than one who has suffered the effects of a wrong decision. Curiously the ‘other ship’ sometimes shares this diplomatic immunity. Discounting ‘acts of God’ then, is there room for a category of encounter in which blame is minimized or even ruled out? In the discussion following a recent paper Captain F. J. Wylie states that between 1948 and 1966 most of the collisions he had studied which had come to court had, according to the Judge, been due to personal error (generally related to the Rules or misinterpretation of radar information). This no doubt reflects the situation in a true light provided one accepts that it may occasionally be necessary to distinguish between ‘personal error’ and blame. The two might not go together, for example, when the error is due to overloading of the human system or under-exposure to congested waters—a view which appears to be gaining support in some quarters.