AN EXAMINATION OF 2 EMERGENCY BREATHING AIDS FOR USE DURING HELICOPTER UNDERWATER ESCAPE

Background: There is a paucity of published work in which the performa nce of Emergency Underwater Breathing Aids (EUBA) has been examined in the wide range of scenarios in which helicopter underwater escape may be necessary. In the present investigation two EUBA were examined: th e Air Packet (AP) rebreather and the Short Term Air Supply System (STA SS) SCUBA set. Method: Young, healthy male subjects undertook simple s imulated helicopter underwater escapes in water at 15 degrees C and/or 5 degrees C. During the immersions the subjects attempted to remain s ubmerged for 60 s while traversing back and forth along a ladder secur ed at a depth of 1.25 m. At each temperature the subjects used AP and STASS twice. The subjects were dressed in the Royal Navy winter sea he licopter aircrew equipment assembly and an aircrew helmet. Results: Bo th AP and STASS significantly extended the underwater survival time of individuals when compared to their maximum breath-hold time (BHT). It is clear from the measurements made of gas concentrations in AP; the volume of air used from STASS; and subjective responses, that the 60-s submersions were achieved more easily with STASS than AP. Conclusion: it is concluded that in conditions similar to those of the present ex periment STASS will give a longer underwater duration than AP, but thi s benefit must be offset: against the possible risk of pulmonary barot rauma associated with the use of STASS, as well as increased training and maintenance costs. Irrespective of the EUBA which is provided, in- water training, preferably including exposure to cold water, will sign ificantly improve the ability of an individual to use it.