polaris missile, a favourite diving term! No I have never done that one! My bends of arisen from helium not air, in the early days of gas diving we used to carry out a deepwater switch from helium based mixes at around 60m this had a double wammy effect in that we recieved somewhat of a massive narcotic shock and a massive outpouring of helium as the tissue groups over presurised. This would lead to an in water bend that would present itself around the 30m mark, leaving you with a choice of another 3-4 very uncomfortable hours of decompression whith a known bend or a descent and repetition of stops at the switch depth. These days we use closed circuit rebreathers and maintain the bottom mix throughout the dive relying on the unit to maintain constant PO2. This gives a favourable deco curve, no narcotic jolt and reduced instance of DCS.
Yes normal means the non O2 range allthough realisticaly you should be fine upto much higher. It is not the altitude it is the rapid depressurization problem that causes the problem following micro bubble seeding. The bubbles are always present, it is the catalyst that causes them to group together like an angry mob that we have to be aware off. In a commercial jet a blow out could be enough to invite all the bubbles floating around your body to a big brain based rave. In a little spamcan we do not have this problem and the time to climb is so slow we do not sned out the party invites.
Yes I know what all the well know books say about flying after diving. It is your choice to follow the very good advice. I am just pointing out the advice is based on liability and not on accurate physiology. So for anyone who does not understand the subject I would suggest your are better off following the guides.