For what it is worth, an opinion with some woulda, coulda, shoulda.
Was rhere really any “Navicational Error”?
By P&DR and CEL/ NAV they got to where RDF could have, should have allowed them to find their way to Howland.
Read the Chater Report (Tighar Archived Documents) and you will see that AE used her RDF in a test flight at Lae and was unable to find a null (get a bearing) on the Lae station. After landing, she “assumed” that the reason was that they were too close to the station.
It is hard to understand how a pilot, knowing that the RDF would lead them directly to Howland once they got to about 200 miles of the island, would take off on a 2500 mile trip completely over water without knowing absolutely that the RDF was working properly.
AE also , apparently, had no understanding of the limitations on the RDFs on the Itasca and onshore at Howland. She kept asking them to take bearings on her using frequencies that their equipment couldn’t operate in. She knew, or should have known, this before takeoff. She didn’t and we all know the result, they (AE and FN) didn’t find Howland.