In the opinion of the writer the bald name “ Pressurisation ” gives a crude and misleading picture of the developments which are now in hand and both he and the organisation to which he belongs, prefer to speak of “ Cabin Air Control,” as this name gives a clearer picture of the scope of the developments which are the subject of this paper.

At the outbreak of the war the evolution of passenger-carrying aircraft had reached a stage where a great deal of attention was desirable for the comfort of passengers and, in those passenger-carrying aircraft which have subsequently gone into service, it is fair to describe Pressurisation as a development directed almost entirely towards the greater comfort of the occupants.