I would like to ask what are the safety requirements when personnel are transported by air and by sea respectively? This is all about going to offshore drilling rig and production?

A key hazard if you are transported by sea is getting access to the drilling rig. In UK waters, it will be well offshore and not designed for open-sea access - so you have either to do a short helicopter transfer, or be lifted on by crane. In other climates (shallower, warmer, calmer waters) boat transfer of personnel may be reasonably safe, but it's judged to be too unsafe in UK waters, except in unusual circumstances. (I've done it once, some years ago, when leaving a small installation after construction was completed). For oil & gas activities almost everywhere, helicopter transport is the normal system, though lifeboats are provided for emergency evacuation (it's much easier to get off than to get back on!). For some construction activities, personnel can live an a boat or semi-sub 'flotel' and access their workplace via a gangway, with arrangements to close/lift this in extreme weather. I'm not so familiar with all current practices for offshore wind turbines - at present these are mostly near shore and boat access is possible in normal weather. But as they move into deeper water it's become clear that won't work and there's lots of effort on innovative methods to provide safe access between a moving boat and the fixed turbine column. So the 'safety requirements' you ask about are pretty complex. You need a competent transport contractor plus design of the interface (gangway or helideck) to an agreed standard, plus well trained and suitably kitted personnel to do the transfer, plus rescue plans and procedures in case of an emergency. That's one reason why in UK and many other offshore sectors everyone going offshore needs to meet defined medical standards and to complete an approval basic offshore survival and emergency training course. Hope this helps. If you want to know more about helicopter safety, IOSH Offshore Group had a useful meeting last week and the Powerpoint presentation is available at http://www.iosh.co.uk/gr...icles/presentations.aspx .