Before I type ANY of this, I must add that I do not reccomend ANY of these practices, and I am just speakinf from my personal experience while travelling as a regular passenger on civill aircraft....
As far as the airlines go... Not many of them even know what an ecig is nor do their research before banning them on their flights. The airline I currently work for had never heard of an ecig before. I was called into the office by inflight management, and they were amazed at what this thing actually was, however asked me to treat it like a real cig until they can get a company wide yes or no answer on its use.
Most airlines you can vape right in your seat without being noticed... especially at window seats.
I just vaped on an American Airlines flight out of Miami sitting right in the First row of First class right by the galley... I was never looked at.
As far as the lavs..... Yes it IS Disgusting to even think of vaping in there, especially the chance of any of the fumes spilling out of the toilet coming anywhere NEAR my atomizer *Shudders* However desperate times calls for desperate measures...
The majority of smoke detectors in airplane lavatories do not detect smoke per se, rather than light density entering the sensor in the smoke detector. So, if you are vaping anywhere near that thing, it will most likely go off, however if you hold your vape in a lil longer, or exhale your vape downward, almost all vapor has evaporated before reaching the detector level.
For TSA- All I can say is Nic liquid is treated like any other liquid when passing TSA for non airline crew members, so remember 3-1-1. It is up to the individual TSA agents disgression as to whether or not something is suspicious or not. So Smile, be polite, ,and answer any questions they ask you. You should be just fine.
I have vaped on many major International airlines with no problems at all. Its so nice to not have to cram into those glass cages in Frankfurt where you dont even have to light a smoke to get nic, justt breathe the clouds in there. Not to mention being looked at like a caged animal in the zoo!
Sorry this post was so long... any questions regarding ecigs and airlines, airports, TSA, and travelling, feel free to PM me!
Safe travels!