There's a lot of misconception out there about ruggedness and IP numbers in general. While most of us just fly in fair weather, police and military applications nearly always require fully water and dust proof gear. While IP-54 is usually enough for all controls in their operating state to be really weatherproof, because of the occasional immersion and the fact that these guys love to use a water jet to clean their stuff, they require IP-67 for at least transport purposes.
