claiming miles without actually taking a flight
 

I am just 1 flight away from elite status. Will I get credited if I buy a cheap ticket for an eligible flight on other airline, check-in, do not fly and later claim the missing miles? Will the airline which runs my FFP be able to check if the ticket on other airline was actually flown? Do they check that when I claim missing miles on other airlines and send them tickets and boarding passes?

They forward your request to the other airline and wait for confirmation that you are eligible for accrual.

So, no.

Kudos to my FFP then - they always manage to get a reply from the other airline within hours of my claim and credit my account with missing miles.

It's automated. Ever wonder what that little "beep" does when you scan your boarding pass enroute to the plane?

That's how they know you flew, knew if you didn't get on the plane and they need to pull your bags, or know if you get in the wrong plane.

Your only option is to scan, get on the plane, then hope the gate agent isn't watching and sneak out... but that could risk some sort of major incident you don't want to be responsible for.

If this worked, no one fly MR's :p

Ha but where's the fun in that ! :o

but not for roundtrip mr

OP doesn't specify his FFP, but many carriers are fully automated and when you make a request for missing credit, they can verify that you actually boarded and were not off-loaded on another carrier in seconds.

Sometimes with foreign carriers, the request is forwarded by email or even fax and can take months.

Either way, it is the operating carrier which is paying for your miles, thus a good reason for them to check that you aren't defrauding them.