I don't know to what standards pilot's helmets are constructed, but there is a variation in motorbike helmet standards around the world, reflected in the individual state's approval stamp.
We are "disadvantaged" in Australia as to what helmets are (legally) available for on road motorcycle use. AS (Australian Standards) have a significantly thicker shell requirement to most other major states (EU, USA, etc) and do not allow helmets to be used on road without the AS/NZ 1698 label. NZ, by comparison, will accept EU and USA labels. The outcome is that major helmet manufacturers no longer produce helmets for the Australian market, due to compliance costs, and that compliance is (basically) a stronger, thicker shell construction to the one used in the Northern Hemisphere.
Relevance to this thread? Not sure, but if you're seriously looking at a motorbike helmet as an alternative to a pilot's helmet (most of which were/are designed to quite high military specs) you
may not get the same level of protection
