Qantas said the captain of the jumbo jet sought priority clearance to return to Singapore as a precaution. There are 412 passengers, three flight crew and 16 cabin crew.

According to Qantas website, Flight QF6 is a Boeing 747-400, which is fitted with four Rolls-Royce RB211-524G-T engines. The daily flight operates between Frankfurt and Sydney with a stopover in Singapore.

The website said the flight is now expected to depart at 11:35 p.m. local time, more than 3 1/2 hours after its scheduled departure. The information indicated that the problem with the engine was not serious and the flight will continue on its onward journey.

After the Airbus A380 emergency landing Thursday, Qantas grounded its fleet of A380s and other airlines made checks of their planes that have the same Rolls-Royce engine. The A380 shed debris from the busted engine onto the thickly populated Indonesian island of Batam.

"Sir," said a guard.

And I knew. I just knew this was going to be something stupid.

"I need you to remove your belt."

"Huh? My belt? Why?"

"All passengers need to remove their belts."

"I'm not a passenger."

"All pilots have to remove their belts."

"We do? Why?"

"Sir, remove your belt."

"Why?"

"Because that's the rule."

"What rule? I never have to remove my belt. The buckle is nonmetallic."

"It's the new rule. All belts have to come off."

"What new rule? I don't understand."

"Sir, you need to take it off."

"But ... What if I don't?"

"Then you'll have to go through secondary screening and a full pat-down."

And so I opted for the secondary screening. Not that a pat-down is reasonable, either, but I did not want to submit to something that I felt was excessive and ridiculous without a reason or explanation.

I was asked to stand in a cordoned-off area, where I waited for several minutes as guards stood around looking at me. Finally a supervisor came over, wearing disposable blue gloves, to administer my secondary screening.

"Sir," he said, "um, you still need to remove your belt."

"What do you mean? I chose this so I could leave the belt on."

"No, either way the belt has to come off."

"What? And if it doesn't come off?"

"Then I cannot let you through."

So, it would seem, secondary screening isn't really "secondary" at all. Instead of simply taking off my belt, I get a full, blue-glove groping and I have to take off my belt. Either that or I'm not allowed to fly the plane.

"Really?" I asked.

"Really."

And with that I started laughing.

Much to his credit, the supervisor also laughed. He smiled, nodded and proceeded to explain this "new rule."

Before getting to that explanation, I will note, for what it's worth, that this particular supervisor, who asked that I not reveal his name or location, was perhaps the most decent and reasonable TSA employee I've ever interacted with. He was courteous and professional, not to mention sympathetic. He acknowledged that much of what flight crews are forced to endure does not make sense from a security standpoint. He does not enact policy; he enforces it. Further, he seemed fully aware of the ridiculousness of the new belts procedure.

Belts, it has been determined, can interfere with the images procured by the new full-body scanners being deployed at checkpoints around the country. And so, from now on, passengers need to remove them.

Now, although we can debate the body scanners from an effectiveness point of view, or from a privacy-rights point of view, separately, this at least makes sense.

Fair enough, except for one thing. As I looked around me, I noticed that there weren't any body scanners anywhere at the checkpoint.

"But sir," I said, motioning to the left and right, "there are no scanners here."

"I know," he replied. "I know. But to keep things consistent, across the board, everybody has to do it."

"Really?"

"Really."

He looked at me. He shrugged and sighed.

It's not his fault, I know.

I took off my belt.

Somebody, somewhere, needs to shake us from this stupor of blind policy and blind obedience. I'm beginning to wonder if this isn't some test -- a test of just how stupid Americans are. If TSA said that from now on we had to hop on one foot while humming "God Bless America," would we do that too?

That'd be ludicrous, certainly, but how much more ludicrous is it, really, than asking people to remove their belts for purposes of walking through a nonexistent body scanner?

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Do you have questions for Salon's aviation expert? Contact Patrick Smith through his website and look for answers in a future column.

The explosive cartridges discovered in Dubai and England were so sophisticated, and so cleverly designed, that investigators described them as "undetectable." Scary, but is that really surprising? Are we dumb enough to believe that by enacting ever more draconian, minutiae-obsessed security measures, we can eventually reach a point of "total safety"? 

Think for a minute about the typical Transportation Security Administration airport checkpoint. We spend billions of dollars and billions of hours every year, rifling through carry-on bags in a hunt for hobby knives and corkscrews, confiscating cutlery from pilots,  and so on. Yet even a small child is bright enough to understand that you can fashion a makeshift and perfectly deadly knife from almost anything. You don't need to smuggle it aboard; you can make it on the plane from a snapped-off piece of metal, plastic, glass or wood. Talk to a prison guard. (Of course, the suicide hijack scheme used by the Sept. 11 cabal is no longer viable, and such a knife wouldn't be of use to a terrorist in the first place, but that's another issue.) 

We can extend this thinking to the search for explosives. Granted, bombs are the No. 1 threat to commercial planes, and have been for decades. We've made large strides in detecting them, and together, the right technology and the right protocols give us greater protection and provide a highly effective deterrent. But only to a point. 

That's not capitulation, it's reality, and a mind-set that in the long run could save us immeasurable amounts of money and undue panic if and when something terrible happens. 

As it has happened before. One Associated Press story described last week's plot as "the latest to expose persistent security gaps in international air travel and cargo shipping nearly a decade after the Sept. 11, 2001, attacks." I would back that up to about 1970. Again we are fed this weird idea that air crimes did not exist, or somehow weren't important, before the 2001 attacks on New York City and Washington. In fact, bombings and hijackings were comparatively rife  throughout the 1970s, 1980s and 1990s, and only since 2001 have things calmed down. 

We've been lucky, but obviously, too, we're doing something right. And whatever that something right is, I suspect it is going on far out of view, in the secret world of intelligence gathering and international policing. Where it should be. The devices in Dubai and England were found thanks to a tip-off. Indeed, ultimately this isn't a hunt for weapons; it's about a hunt for those criminals and terrorists who would use such weapons, and the most effective way of thwarting an attack is to catch it in the earliest possible stage, before the terrorist has a chance to set his plan into motion. 

This one, similar to last year's Christmas Day "underwear bomb," was a little too close for comfort. It's a wake-up call, perhaps: a reminder to stop fussing around with butter knives and Ziploc bags and get our priorities straight. We will never be totally safe, which is Lesson 1. But Lesson 2 is to strive to be as safe as we reasonably can be. And no, we're not there yet. We're not there because too much of what we do in the name of security isn't about security at all. This self-defeating approach has cost us plenty of money and time. Sooner or later we'll be measuring the cost in lives.

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Do you have questions for Salon's aviation expert? Contact Patrick Smith through his website and look for answers in a future column.

Yemen is the home of the al-Qaida branch that claimed responsibility for an attempted bombing of a U.S.-bound airliner on Christmas.

The official spoke on condition of anonymity to discuss the ongoing investigation.

THIS IS A BREAKING NEWS UPDATE. Check back soon for further information. AP's earlier story is below.

PHILADELPHIA (AP) -- A suspicious package containing a toner cartridge with wires and powder was found during routine screening of cargo in the United Kingdom, prompting authorities to scour three planes and a truck in the United States on Friday.

Searches were conducted in Philadelphia, Newark, N.J., and New York City, but no explosives were found. All the packages believed to be suspicious came from Yemen and were being sent via UPS.

Officials found a suspicious item during a basic security screening process in the United Kingdom, according to a U.S. government official who spoke on condition of anonymity to discuss the ongoing investigation.

U.K. officials discovered that a toner cartridge on the plane had been manipulated and found wires attached to it and white powder. Tests on the device came back negative for explosives, according to a law enforcement official who also spoke on condition of anonymity to discuss the investigation.

All the packages being investigated in the U.S. originated from a specific address in Yemen that is connected to the suspicious device found in the U.K., the law enforcement official said. The official would not say where in Yemen the package came from.

Concerns about the possibility of similar and potentially dangerous devices shipped elsewhere prompted officials to check other cargo headed to the U.S.

Transportation Security Administration spokeswoman Kristin Lee says the planes in Philadelphia and Newark were swept. The planes were moved away from terminal buildings so law enforcement officials could investigate.

Two Philadelphia jets belonging to UPS were searched. A federal law enforcement official, who was not authorized to provide information on the investigation, told the AP that nothing suspicious was found on them.

A source with knowledge of the situation in Newark who was not authorized to speak said the FBI and a bomb squad checked two packages there and gave the "all clear."

New York Police Commissioner Ray Kelly said that the NYPD removed a package from a UPS truck in Brooklyn, tested it for possible explosives and found it not to be dangerous. The package was an envelope that came from Yemen, appeared to contain bank receipts, and was addressed to the JP Morgan Chase bank in Brooklyn, Kelly said. The package arrived on a plane that landed at Kennedy Airport, he said.

Yemeni authorities reached by the AP declined to comment. Many offices were closed because Friday is a day off in Yemen.

Mike Mangeot, a spokesman for Atlanta-based United Parcel Service Inc., said two planes in Philadelphia that had come from Cologne, Germany, and Paris were being investigated.

"Out of an abundance of caution, those aircraft have been isolated, and they are looking into the shipments in question there," he said.

A third plane had arrived in Newark, N.J., from East Midlands airport in England. That plane was cleared and flew to UPS' main hub in Louisville, Ky., on its usual route, Mangeot said.

In central England, police had evacuated a freight distribution building at East Midlands Airport after a suspicious package was reported at 3:30 a.m. Police and emergency workers examined the package and lifted the security cordon by midmorning, but Leicestershire Constabulary later said officers were re-examining it "as a precaution."

Sarah Furbank, a passenger who was about to board a plane out of East Midlands Airport, said that she had noticed an increased security presence.

There were "quite a few police cars round the edge" of the airport, Furbank told The Associated Press. "Apparently there was an incident earlier according to staff but they didn't go into detail."

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Sullivan reported from Washington. Associated Press writers Randy Pennell in Philadelphia, Joshua Freed in Minneapolis, Colleen Long in New York, Shawn Marsh in Trenton, N.J., and Sylvia Hui, Jill Lawless and Raphael Satter in London contributed to this report.

U.K. officials discovered that a toner cartridge on the plane had been manipulated and found wires attached to it and white powder. Tests on the device came back negative for explosives, according to a law enforcement official who also spoke on condition of anonymity to discuss the investigation.

Concerns about the possibility of similar and potentially dangerous devices shipped elsewhere prompted officials to check other cargo headed to the U.S.

Transportation Security Administration spokeswoman Kristin Lee says the planes in Philadelphia and Newark were being swept. The planes were moved away from terminal buildings so law enforcement officials could investigate.

The Philadelphia jet belonged to UPS. A source with knowledge of the situation who was not authorized to speak said officials in Newark were examining a UPS package.

In New York City, police responded to reports of a possible explosive in a UPS truck at the Queensboro Bridge, top NYPD spokesman Paul Browne said. Browne said the package was removed and was being examined in Brooklyn.

Mike Mangeot, a spokesman for Atlanta-based United Parcel Service Inc., said two planes in Philadelphia that had come from Cologne, Germany, and Paris were being investigated.

"Out of an abundance of caution, those aircraft have been isolated, and they are looking into the shipments in question there," he said.

A third plane had arrived in Newark, N.J., from East Midlands airport in England. That plane was cleared and flew to UPS' main hub in Louisville, Ky., on its usual route, Mangeot said.

In central England, police had evacuated a freight distribution building at East Midlands Airport after a suspicious package was reported at 3:30 a.m. Police and emergency workers examined the package and lifted the security cordon by midmorning, but Leicestershire Constabulary later said officers were re-examining it "as a precaution."

Sarah Furbank, a passenger who was about to board a plane out of East Midlands Airport, said that she had noticed an increased security presence.

There were "quite a few police cars round the edge" of the airport, Furbank told The Associated Press. "Apparently there was an incident earlier according to staff but they didn't go into detail."

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Associated Press Writers Eileen Sullivan in Washington, Joshua Freed in Minneapolis, Shawn Marsh in Trenton, N.J., and Sylvia Hui, Jill Lawless and Raphael Satter in London contributed to this report.