Apparently, these two words will guarantee you an airline upgrade EVERY. SINGLE. TIME.

There are a lot of uncomfortable things about flying. Being stuck on the aisle seat and having the annoying person on the window climbing over you four times to use the bathroom.

Falling asleep mid-flight and missing that all-important delivery of a tiny bottle of water and a bag of extra salty peanuts. Trying to make the free, scratchy blanket cover your toes AND reach up to your chin all at the same time (it’s…it’s impossible).

So, upon check-in, a wave of relief floods over any passenger who hears those magical words: ‘We’re upgrading you’.

They’re so magical, in fact, they really should be accompanied by the sweet sounds of harps and a PA announcement declaring a TRAVEL MIRACLE has occurred.

For many travellers, those words may never come. But best-selling British author Tilly Bagshawe recently told Bloomberg there's just one phrase travellers need in their arsenal to get an upgrade every single time.

The author, who estimates she travels around 100,000 miles a year, said all holidaymakers need to do is utter the words "revenue management".

LISTEN: We need to talk about why you should never, ever recline your seat back on a plane. Post continues after audio.

The unsexy words will set you apart from other travellers, and cement your status as someone who knows what's what when it comes to flying.

"If ever we've flown anywhere up front, we've used miles to upgrade from economy," Tilly said.

"If you want to do that, call reservations and drop the name 'revenue management'. Say to the agent: 'Have revenue management released any first-class seats for miles upgrades yet?'

"When they say no, ask them to check or just be put through to revenue management so you can ask when they will release some, as well as how many seats are left."

There is, however, a particular script those seeking to upgrade should stick to.

"Politely respond like this: 'You have 20 seats unsold? Why aren't you releasing them?'" she suggested.

"Often by the end of the conversation they say, 'OK, we'll release one for you,' or they might tell you to call back tomorrow. Doing that, we've had a pretty much 100 percent success rate."

There is, of course, a catch: the upgrades don't come for free, and travellers must use their available frequent flyer miles or points to 'purchase' the business or first class seat.

Then it's simply time to sit back, relax and enjoy the flight. And possibly send a glance of commiseration back to the passengers stuck in economy who don't yet know about the clever trick.

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