The incident, which occurred in the foggy waters near the Nantucket Light Ship in 1956, was a classic radar-assisted collision that had a full complement of the typical wrong assumptions, mistakes and judgment errors. It’s also a showcase for the human factors that continue to confound us decade after decade.

It was mainly a simultaneous failure by the watches of both ships to take adequate action to avoid each other as the two ships approached head-on at relatively high speed in poor visibility. This is an important point — head-on or nearly head-on. Is there a difference or should there be? No, they should be treated the same. Because historically it’s been the act of trying to parse a difference, real or imagined, between them that too often has brought vessels into direct physical contact with each other. The Andrea Doria and Stockholm were cutting it too close for comfort. It was the strong desire of both watches to avoid substantial course changes or reductions in speed, either of which could have saved them, that caused the collision. They wore rose-colored glasses right into disaster.

To consistently operate with minimal safety margins, which is inadvisable, also requires a correspondingly high level of skill. It’s easy to find mariners who routinely overestimate their skills. 

Cahill wrote that the Stockholm’s mate “probably fell into the most common trap of all. He let his pride override his judgment. That is one of the most frequent and serious mistakes made by watch officers. Even those who have no good reason for it often take an inordinate pride in their skill as navigators. To call the master seems to be an admission of inadequacy. Although many may know that this is not the case, they are reluctant to appear so in the eyes of their subordinates.” 

Pride goeth before a fall.