When an expensive orthodontic appliance goes missing, who’s at fault -- the passenger or the flight attendant?

After the main-cabin dinner service on a long-haul international flight, I collected one meal tray after another, dumping the trash into my rolling garbage cart.

When I finally reached the last row I felt an unfriendly double-tap on my shoulder.

I turned and faced a man who seemed to snarl as he spoke. “You threw away my retainer,” he said.

He stood in the aisle, eyes set, feet apart, like a gunslinger itching for me to draw. I took a step backward as he fired a hasty explanation.

He had removed a costly orthodontic retainer, he said, from his mouth and placed it on his meal tray before dining. He blamed me for throwing it away.

In an effort to shield myself from such allegations (“You threw away my diamond ring … my cellphone… my passport”), which happen more often than you might think, I usually ask passengers to hand me their unwanted meal trays.

This tells me they are done with the tray and that the leftover mountain of trash (half-eaten food, empty wine bottles, shredded documents, wadded gum and, on occasion, a bulging airsickness bag) is to be discarded.

Merely asking whether a passenger is finished with his or her meal tray is sometimes not enough because that flier can later argue that no, he or she wasn’t done.

But when someone picks up his own trash-laden meal tray and hands it to a crew member, there’s no mistake. He’s finished with it. The tray and everything on it is garbage meant for immediate disposal.

The garbage collector, er, flight attendant, isn’t expected to dig beneath the debris on the off-chance something of value may be hiding beneath a crumpled napkin.

Despite my precautions, the man insisted I was to blame for discarding his mouthpiece.

“You threw away my retainer!” he said, jabbing a finger at me as he spoke. “It was on my tray.”

Putting up both hands in peaceful protest, I said, “Whoa. I’m sorry your property has gone missing. But you handed me your tray, sir. Maybe your retainer….”

“Doesn’t matter,” he said, cutting me off before I could ask whether he had searched for the missing item in the area near his seat. “You’re just going to have to retrieve it.”

“I’m really sorry,” I replied. “But I didn’t throw away your retainer, sir. You did.”

I promptly handed him a pair of latex gloves. To his surprise, I pulled out the enormous garbage bag stuffed with the detritus of 100 passengers and told him to have at it.

Had he been nicer or even if he had approached me in a less hostile manner, I would have donned a pair of gloves and dug through the garbage with him.

(I did exactly that, on a different flight, after a sobbing woman told me she had left her wedding ring on a meal tray she had given me for disposal. After half an hour of digging, I found the ring.)

But this guy was rude and more than a little condescending. There’s no directive in our Flight Attendant Manual that requires crew members to dig through garbage looking for property that may have been discarded by a jerk.

He meticulously dug through the trash and after briefly inspecting each piece he tossed the material into an empty garbage bag I had provided. No luck. The retainer was never found.

Our flight landed and the disgruntled passenger disembarked. I suspect his first phone call was to the orthodontist. His first email, it seems, was to the airline’s complaint department.

Shortly thereafter, I received a phone call from my supervisor who proceeded to read a section of the complaint letter aloud. (Believe me, passenger complaint letters are read and attended to.)

According to him, I had maliciously removed his meal tray without his knowledge or approval and in doing so I carelessly threw away the $800 retainer sitting beside his half-eaten chicken piccata.

He demanded the airline reimburse him.

I don’t know whether the carrier honored his payment demand. But I told my supervisor the same thing I said to the passenger: “I’m really sorry. But I didn’t throw away his retainer. He did.”

travel@latimes.com