Mom was right: Be polite, even on airplanes

Seat etiquette can be the difference between an uneventful flight — and the alternative. Consider, for example, the passengers on a recent United Airlines flight from Sydney to San Francisco who had a conversation over another seated in the same aisle.

The middle-seat passenger didn’t take kindly to it, reportedly delivered a racist rant and ultimately forced the airline to divert the flight to New Zealand.

The incident raises the question: Is it acceptable to hold a conversation over someone in a middle seat?

“Yes and no,” says Maggie Oldham, a New York-based etiquette coach. The conversation must be brief. But if it’s anything longer than “a quick exchange,” then no.

“The polite thing to do is for one of those passengers to offer to trade seats with the passenger in the middle seat,” Oldham says. “Even better if you ask the middleseater if they prefer the window or

the aisle and then abdicate accordingly.”

Here are a few other situations to consider. Q: Should I lean back my seat in economy class?

A: No. Seriously, no. Even though you can theoretically lean your seat back, most airlines have removed so much room between the seats that you’re almost certain to collide with a passenger’s knee, laptop computer or lap child. And that’s likely to provoke a confrontation. Q: Whose armrest is it, anyway?

A: Obviously, the passenger in the window seat controls the window armrest and the aisle seat controls the outermost armrest. But the middle two armrests — that’s not an easy one. The consensus is that it’s a shared space

but that the middle seat passenger has something close to the right of way. If you’re sitting in a window or aisle seat, the middle seat passenger gets to put his arms down first. If there’s room left over, great.

One more thing, says Adeodata Czink, a Torontobased manners expert, “Try to be nice about it.” Q: Should I awaken a snoring seat mate?

A: If the snoring is keeping you awake on an overnight flight, absolutely. But the burden is on the snorer. “If you know you have a snoring problem, you may need to avoid sleeping,” says Maryanne Parker, an etiquette expert from San Diego. The best approach: Ask a flight attendant or conductor to help. You might be able to move to a different seat. “If the passenger himself asks us if we can hear him snoring, you can be honest, but still polite,” she says.

ISTOCK Reclining one’s seat in economy class is never a good idea and could cause a fight.