The indispensability of such a training stage foregoing the practical hydro - spatial tests is far too evident, comparing the training activity of psychological and technical character of an applicant professional diver (bathynaut) with the one of an aspirant astronaut not allowed to train in an hypobarism-simulator previously to the space-mission.

The aspirant diver technician is to overcome technical, instrumental and psychological problems exactly as the aspirant astronaut, though operating in a diametrically opposed environment.

Disposing a practical training cycle restricted to the diving as such, would leave the students exposed to unnecessary and excessive risks, due to the lack of training "graduality" in the step from the swimming pool to external waters, which only the intermediate passage in a pressure-simulator like the hyperbaric chamber can guarantee, in terms of serious and concrete accident-prevention.

During the sanitary checks for the admission to the courses, involving the getting through of various tests controlled by a medical board, the applicants must already demonstrate that they don't suffer, amongst other things, of psychic problems connected to the claustrophobic aspect during the practical test in hyperbaric chamber.

Everything already expressed and referred to the training stage in hyperbaric chamber is oriented to:

	train the student to move in extremely limited areas with rationality and avoiding claustrophobic events;
	teach them the irreplaceable technical knowledge in order to guarantee an assistance inside the hyperbaric chamber;
	train them to control rhythm and ventilation-volume, with greater Pp concentration of the different gases, proportional to the growing of A.P. (Absolute Pressure) volumes, particularly referred to nitrogen (N2) and carbon-dioxide (CO2), compared with the normobaric ambient the human organism is used to;
	teach them the protocols and procedures to be adopted in case of emergency and to prepare the required first-aid through the availability of at least another hyperbaric system , positioned in the same training/operative place as the hyperbaric chamber named "mother", engaged by the students for their formative/experiential phase and ready for use in case of emergency;

Both chambers, as provided for by the legislative provisions presently in force in Italy (DPR 321 March 20, 1956 and D.L. 626 September 19, 1994) are operated by qualified technical/hyperbaric personnel (H.T. = Hyperbaric Technician), professionally acknowledged by current laws in matter of Vocational training needed in every stage of the chamber's operation, with the continuous presence of a physician expert in hyperbaric matters.

Furthermore, for the complete managerial end preventative accident-prevention efficiency, the hyperbaric chamber must be operated disposing at least of:

	a professionally qualified Technical Diver Operator (TDO), according to the current laws in matter of forming and vocational training, necessary for the writing-up of graphic analysis of Comp./Dec.;
	b) a second professionally qualified Technical Diver Operator, for the time-keeping and the analysis of the Comp./Dec. Readings;
	a third TDO, in stand-by, ready to intervene inside the hyperbaric chamber in use for training, in order to guarantee technical and pseudo-sanitary first-aid for anyone encountering difficulties;
	an expert physician inside the hyperbaric installation, ready to intervene in case of sanitary emergency;
	a second expert physician inside the hyperbaric chamber, ready to replace his colleague, should the latter be in temporary difficulty or unable to intervene on the students inside the chamber.

During the hyperbaric tests sustained by the students, the corrected and final Compression Program/s (C.P.) of the Comp./Dec. phase are processed, recording any anomaly in the psycho-physical behavior of each single student the technicians and physicians should notice.

During the permanence in hyperbaric chamber, reaching the bathymetry of - 50, the students will be engaged with various psychological, manual, intellectual, mnemonic and reflex tests, developing the mental skills which are to guarantee the actual submersion's security.

As already said and due to the DPR 321 March 1956, presently in force in Italy to warrant the prevention of accidents and the operative SECURITY of the hyperbaric system's occupiers, a second hyperbaric installation is needed to be placed side by side the one in use. The TWO hyperbaric systems (both operating in low pressure) will be equipped with at least:

	a MAIN CHAMBER, great enough to allow the passage of one person at a time, without any difficulty;
	a EQUILIBRIUM CHAMBER, great enough to allow the passage of one person at a time, connected to the MAIN CHAMBER through adequate hatches, necessary to guarantee first-aid inside of it;
	a CHAMBER double assistance ambient, with equilibrium chamber and main chamber in an unique device, for emergency and first-aid, situated in the same place where the "mother" chamber operates;

During the vocational training years of TDO's and HT's, it has been amazing to establish the technical-operative skill and the growing psychological adaptation demonstrated by students in hyperbarism after this cycle of practical experience, leading the School to look upon this training stage preceding the submersions as an irreplaceable mean for the development and the psychological and technical training of the students.