And how much of that is the faux Pelican vs. the contents?
15 lbs is probably fine if that's all you're carrying on. Add 10 lbs+ in batteries, a prescription dive mask, a dive computer, an HID canister light plus the usual sorts of things a prudent traveler carries on board in case of luggage loss (change of clothes, toiletries, etc) and it starts to be an issue.
I don't use a canister light, I carry all the other dive gear in, mine and my wife's, in one roller diver bag. Four S90 batteries and two sets of AA Eneloops do not weigh 10 pounds. The camera goes in my carry on Pelican and the computer and "travel" items go in the backpack with the computer. If they knock us down to only one carry-on/personal item per person then my wife will carry the backpack with computer, I the camera.
I have spent several years now miniaturizing both her and my dive gear and stripping all the extras out including the reasoning behind the FIX90 rig, to go small and light. Our gear is very compact and lightweight now. We don't take alot and especially a canister light

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Our travel gear for two people:
One roller diver bag with two sets of scuba gear etc
One roller suitcase with two people's cloths etc
One carry-on backpack with "stuff" and computers and laptop
One carry-on Pelican case with complete S90/FIX housing and bits and pieces
The kitchen sink stays at home for international air travel. Now, if we are driving, like in towing our Boston Whaler to the Gulf or the Keys or GLs etc, we take more stuff.
But a "larger" SLR type soft case might work with the FIX90, two S2000 strobes and one or two wet lenses, something to think about, and dang, I just gave a nice one away to a student photographer along with a darkroom outfit, dang it.
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