Tornadic Tubes - Braniff BAC One-Eleven crash 1966
I read the NTSB accident report of the Braniff BAC One-Eleven - registration N1553 - that broke up in severe turbulence near Falls City, Nebraska, USA on 6 August 1966. Although inadvertent penetration of a roll cloud was mentioned, there were many witnesses that testified the aircraft was in clear air at the time it disintegrated. Later reserach By Dr T. Fujitia of the University of Chicago revealed the presence of what were called Tornadic Tubes that are part of tornadoes and which can travel in clear air between storm build up's.
I have searched the internet but am unable to locate speciic reference to this weather phenomena. Many years ago, ICAO published a series of Aircraft Accident Digests known as ICAO Circulars. I recall the Braniff BAC One-Eleven accident was published in one of those ICAO Circulars but I don't know which issue. That particular accident report showed a diagram of how tornadic tubes weave through certain cloud masses.
Can anyone point me to a reference of the existence of this weather phenomena?