The pathologic and the clinical observations in cases of loss of hearing from airplane flight are the subject of this communication. The usual hereditary, vascular, toxic and bacterial causes of deafness are not considered unless modified by flying or flying machines. DEAFNESS FROM DESCENT Acute Type.—A frequent type of deafness from flight both among passengers and crew is the result of a change of pressure in the middle ear following improper function of the eustachian tube during and after descent. Failure to equalize the pressure in the middle ear results in injury to the mucosa of the middle ear. This has been called "otitic barotrauma"1 or more properly "otic barotrauma."2 Relative difference in pressure quickly produces suction on the mucosa of the middle ear and an inflammatory reaction; i. e., it produces traumatic otitis media. Since inflammation occurs, it is correct to designate this disease as otitis. Similarly, a blow