Fitted with HA-LP/PPB oxygen mask.
With the introduction of NVG (Night Vision Goggles) systems on helicopters in the early 1990's the Swiss AF began to explore the possibility to upgrade/modify the SPH-4 in use at the time to the SPH-4B configuration. The objective was to improve the wearing comfort and stability of the helmet, the SPH-4 B fitted with a TPL liner, hopefully resulting in less pilot fatigue.
Unfortunately, the program took a substantial delay due to various reasons, and in the meantime other helmet models which were potentially compatible with NVG installation had appeared on the market.
All of them were tested, with eventually the SPH-4B being judged not satisfactory and the HGU-56 as "nicht truppentauglich" (not suitable for troop use).
The tests with the Guenau ZEUS (H2V “MOD”) continued into the early 2000's, and again, yet other new models appeared on the market. Among them were the ALPHA (Advanced Lightweight Protective Helmet for Aircrew) 200 made by Helmet Integrated System Ltd. and the MSA Gallet LH250. Both were added to the evaluation list.
At the end of the assessment, around 2005, the ALPHA 200 was selected as the new Swiss Air Force NVG-compatible helicopter helmet.