Aero Vintage Books

Does anyone have a clear definition of CL-26/Class 26?
CL-26/Class 26 is generally regarded to apply to a ground instructional airframe but there are many examples of aircraft written off in a fatal accident being ‘recommended for, or placed in Class 26’ and which are very unlikely to be used for subsequent ground instructional use, even if it only consists of components.
One such example is B-17F 42-6031 which crashed after a mid-air collision with B-17F 41-24621 over the Gulf of Mexico, forty miles southeast of Galveston Field, TX 10th September 1943. Both planes are reported to have sunk and their crews are still missing.
Also related are Class 01A and Class 01Z; where do they fit into ground instructional training?

CL-01Z Those aircraft which are not beyond ecnomical repair, transfered to Class 01Z
CL-12 To a museum (aircraft no longer in USAF inventory)
CL-25 Survey/surveyed
CL-26 Mock up (aircraft no longer in USAF inventory)
CL-26 Ground instruction only
CL-26 Those aeronautical items (excluding complete aircraft) which are required or which are placed by order of a surveying Officer as ground instructional training equipment
CL-32 USAF Museum
CL-O1A An AAF property class for complete aircraft
CL-O1Z All complete aircraft assigned for ground instructional training

You also have on the aircraft cards the Flyaway Condition studies which appear near the delivery information

Thank you, but how does Class 26 apply when the complete aircraft is missing on the bottom of the Gulf of Mexico?

I would suspect a plain old error, perhaps?