Training and Operations in Field : Bridging the Quintessential Gap

Night operations are envisaged to play an increasingly important role in future combat. In IAF, NVG flying in helicopters commenced in 2002. In absence of previous experience in NVG flying, SOP’s laying down conditions for NVG exercises were derived from existing night flying SOP’s for helicopter flying. With increasing NVG experience of IAF aircrew, a few anomalies in SOP’s have been brought out which may have flight safety connotations. This paper attempts to review and answer the aeromedical issues raised in field by aircrew experienced in NVG operations. It was commented that the inter-pupillary distance (IPD) must be measured, documented and known to the pilot in the field since its variation affects the visual acuity. Findings of a study carried out at IAM indicate that varying the IPD does not affect visual acuity. Hence, it is recommended that although IPD can be recorded, too much emphasis should not be laid on IPD during focussing except to ensure complete circle in visual field. It was brought out that all aircrew should be viewing thorough NVG at 0 diopter setting. This was not agreed and the reasons thereof have been discussed. It was suggested that flying in higher than minimum requisite illumination (0.01 lux) should be permitted even if the elevation is less than 30 degree. This too was not agreed to and the reasons thereof have been discussed. It was also brought out that aircrew resort to subjective assessment of available illumination before proceeding on mission. The need of objective assessment of night light using suitable lux meters is endorsed. The issue of improper helmet fitment due to sharing of helmets and inadequate training has also been addressed. In addition, fresh issues of degradation in NVG visual acuity in mild to moderate hypoxic conditions and of integration between NVG Gallet helmet and aviators Oxygen mask as revealed in a study recently carried out at IAM are also discussed. IJASM 2012; 56(1): 29-38