Are you —  like me, lately — up in the air more than you’re on the ground? Does sleeping upright with some stranger snoring sweet nothings into your ear seem normal?

Just because you’re a frequent flier doesn’t mean you know everything there is to know about flying. You may be missing out on miles. Or wondering why those miles you were sure you were getting haven’t shown up on your account. And never will.

I’ve been there.

As I’ve explained, I flew around the world knowing I wouldn’t rack up very many miles. The airlines I chose didn’t belong to the frequent-flier groups I frequent: Star Alliance (US Airways and others) and oneworld (American Airlines, etc). And that was OK with me.

But today, with the Mideast part of the trip long over, I find out Qatar Airways, though not a member of Star Alliance, is a partner.

What that meant was that I might get mileage credit for the Qatar flight in my US Airways frequent flier account. An extra (and unexpected) 6,600 miles — flying from  South Africa, up to the Middle East, back down to the Maldives, in the Indian Ocean.

Then I found out that depending on the class of service, it could be all or nothing.

Luckily, I still had my e-ticket from AirTreks, the company that put my round-the-world trip together. It showed I flew economy, which I knew. The class was “H.”

Jackpot, sort of. According to the dividend miles rules on the US Airways site, that qualifies me for 50 percent of the miles flown on Qatar. That 3,300 miles is better than nothing. But there was a big catch: I needed to send my boarding pass to the nice dividend miles folks at US Air.

Which I didn’t have, because I never thought the Qatar flights qualified for miles. I was trying to clear out the clutter from my trip, so I threw out the boarding passes. As if discarding two scraps of paper would lighten the load.

Here’s hoping the e-ticket with all the info will be enough.

The other time, when I flew round-trip from Philadelphia to Prague over the winter, miles that I was expecting never materialized. Again, it was the kind of economy class I flew. Apparently they can all differ — even on the same flight.

So the moral of the story — at least for me, is — save your boarding passes for awhile. If you’re flying a different airline than usual, check the affiliation. Along with those all-important flight details.

Will I end up with more than just this sleep mask and travel toothbrush from Qatar Airways? Maybe not, since I didn’t save my boarding passes.