What is the expected accuracy error of NAD27 in Hawaii?

The expected accuracy error of the North American Datum of 1927 (NAD27) in Hawaii is indeed around 400 meters. NAD27 was developed using a terrestrial-based survey system, which catered mainly to the continental United States. When applied to Hawaii, there are significant discrepancies due to the differences in geodetic datums and the island's unique geological features.

The error arises because NAD27 was not optimized for the latitude and longitude positions specific to islands like Hawaii, leading to a notable shift in positional accuracy when mapping coordinates against the current geodetic framework. Consequently, using NAD27 in Hawaii can result in large inaccuracies, estimated up to about 400 meters, as this datum does not take into account the complex terrain and the distance from the reference ellipsoid it was based on.

As a result, while other errors stated in the choices may seem plausible, they do not reflect the large scale of inaccuracy seen when NAD27 is applied to the Hawaiian coordinate system. This makes 400 meters the most accurate figure for expected error in this context.