"Triskaidekaphobia," he said while shaking my hand.

"Pardon?"

The man spelled the word. "Dread of the number 13," he explained, pointing to the numerals scrawled on his boarding envelope. "Ever notice, no flight 13's?"

"How do you happen to know that word?"

He handed me a card from his vest pocket. I learned that he was a salesman for an elevator manufacturing company. "I come across triskaidekaphobia all the time," he said. "Just think, here we are nearly two-thirds of the way into the twentieth century, jetting around in the sky, putting a man on the moon, and..." He raised his eyebrows and waited for the light to dawn.

"And still no 13th floors!" I exclaimed.

The man studied my card. "How's business?" he asked. My answer was irrelevant. He formed a solemn expression. "In the elevator industry, we have our ups and downs."

s for quality conversation in the sky, I admit that so far this is hardly a case in point. However, by the time our plane reached cruising altitude, the fellow, whose name for some reason would stick in my mind for decades, P. T. Barton, had thoroughly engaged me in a baffling riddle.

Elevators provide a transportation service, Barton explained. The value of that service depends on the perception of speed. Practical realities, though, limit how fast you can move a capsule full of people. Just as crucial is waiting time. You can improve waiting time only by having plenty of elevators in the first place. But how many?

My bow-tied seat-mate ordered a second drink and continued with his explanation. "Bigger buildings, of course, require more elevator shafts. But even in a small building, you better plan on extra elevators if there are really high peaks in demand, otherwise the waiting time would become intolerable."

"What if you guess wrong?" I asked. "Can you add elevators after the building is built?"

"Sure, but it's expensive," said Barton. "Our industry has a slogan: 'Shaft the building, not the tenants.'" He paused for my mandatory groan. "My company uses a formula to tell us how many elevator shafts are needed. It's based on expected traffic loads, number of floors, and so forth -- plus 'the grumble factor'."

"Grumble factor," I mused.

Barton stirred his drink with a plump finger. "Can you keep a secret?" he asked. Once again, my answer was of no consequence. Barton leaned toward me and lowered his voice. "We have found a way to reduce the number of elevator shafts without causing complaints."

"Fewer shafts?"

"About one-third fewer!"

"You want me to guess how," said I. Barton stroked his nose and nodded smugly. I watched the landscape sliding by miles below. "Nothing to do with elevator speed."

"Definitely not."

"Nor recorded music, I suppose."

The man shook his head. He watched my face contort into a frown of concentration. Neither of us spoke until the dishes were bussed away after our meal.

"Care for a hint?" asked Barton.

"Not yet."

Barton smiled agreeably. He donned spectacles and thumbed through a trade journal, probably Lift Magazine. In due course, the plane began its descent into Chicago O'Hare. I looked over at Barton and shook my head.

He pursed his lips. " 'SVP' -- that's our abbreviation for it."

"S, V, P," I repeated. "You call that a hint?"

"All right," he said. "This is important. We are talking about an accessory for the elevator system -- are you ready for this? -- with no moving parts!"

"And people will put up with longer waits," I confirmed.

P. T. Barton nodded. "So much so, that for any size building, we can save one shaft in three."

Our plane completed its taxi to the gate. I glanced down at the bustling ramp.  The seatbelt sign was turned off. Barton stood in the aisle and reached for his briefcase in the overhead compartment.

"All right," said I.  "What's the secret?" I looked back, and P. T. Barton was gone, swept forward by the tide of deplaning passengers.

ver since that flight, anytime I have to travel aboard one of those black-nosed, bent-wing, silver-bellied kerosene suckers, I request a seat in Row Thirteen. There are two things I always know about the person sitting next to me: He or she is not superstitious. The second thing: Over the years, every person I meet in Row Thirteen has been an accomplished story-teller. Coincidence, you say?

My seat-mate in Row Thirteen for one trip to Philadelphia was a member of the board for Readers Digest, a distinguished gray-haired dandy whose name, if I am not mistaken, was Chapman. He favored talking more than listening, which is fine with me. Anything to displace the monotony of jet flight.

The man told several anecdotes. One reminded me of 'the grumble factor.' I began a recitation of P. T. Barton's elevator riddle, explaining to the gentleman from the Digest that I had not been able to catch up to Barton in the baggage claim area at Chicago that day. Instead, upon returning to California, I called his office.

Barton's secretary had laughed. "So he used the old 'SVP Story' on you. No problem. I'll mail you our product literature. What's your address?"

"You mean it was a ploy?"

"One of the pieces I'm sending will answer all your questions about our elevator systems, including the SVP. Are you the architect or the general contractor?"

"I'm not building a building," I explained.

"When is the groundbreaking?" asked Barton's secretary as if I had not spoken.

Chapman, the man from Readers Digest, chuckled knowingly. "Every business has its secrets," said he. "Reminds me of our complaint system."

The old fellow in Row Thirteen was eager to tell his own anecdote. My punch line about elevators would have to wait.

hat may have been Mr. Chapman's favorite business story dated back many years -- long before the term 'automation' had even been coined. With tens of millions of readers, sheer size characterizes most business operations at the Digest. Every month, subscribers by the thousands write to the publisher. "A small fraction of the total circulation, to be sure," said Chapman, "but a huge number just the same -- and they have a variety of reasons for writing. Mountains of incoming letters arrive each day, all requiring answers. Imagine, truckloads of mail backed up to the docks. Enormous costs."

A 'system' was needed. Enter Mr. Chapman, my new friend in Row Thirteen, and his concept was ingenious as hell.  Here, you can decide that for yourself.

"We installed a conveyer belt out at the receiving dock," he said, squinting -- the better to recall the layout. "Over there at one end was the mail-bag culling area. We trained laborers who could not even read to tear open envelopes, unfold the letters inside, and staple them together." As he spoke, the old gentleman pantomimed each of the manual operations on the tray-table before him. "Downstream was a handful of high-paid readers. They were instructed to skim only the first sentence in the letter. Then, they would simply -- "

"Excuse me for interrupting. They read only the first sentence?"

"That was the best part of the whole system," Mr. Chapman said with a fully wrinkled grin. "Let me go on. I think you'll see why." He held a napkin to simulate a letter. "After reading the first sentence -- often just the first few words -- the reader made a decision, one of only five selections. Each had its own conveyer belt leading into the various stuffing shops. We had personnel there with typewriters, addressing the responses. Others stuffed the envelopes with pre-printed pages.  There was a sealing station.  At the end of all five conveyers, of course, were wastepaper hoppers to carry away the inquiries."

"Only five selections," I repeated to myself.

Mr. Chapman nodded. "Five belts, don't you see." He told me that one was for change of address, another was for complaints about articles, another was to correct errors. The reproduction department carted in bales of responses for each of these. "The company trained armies of people for the horrendous volume. It is really something to see."

"That sounds like a 'real-time' system," I remarked. "You dare not fall behind."

"Oh yes," he added, holding up his index finger, "and one work station handled cancellations."

"There must have been a lot of errors," I said with alarm.

"Not so many as you might think," said Chapman, smirking. "According to one study, 80% of the letters were answered correctly the first time."

"Four out of five?"

"It was what Post Office people call a 'self-correcting system.' The Post Office -- hell, they have workers in some places -- most people don't know this -- they have workers sorting mail who can't even read. Not that it matters much. Most of the mail gets forwarded to where it is supposed to go."

"Eventually," I commented. "What about the 20% who receive wrong answers from the Readers Digest?"

"Well, something like 50% don't write again."

"And the other half?"

"About 80% of them receive the right answer," said Mr. Chapman. "Most of the others won't try a third time." The man laughed out loud, and I joined him. "Human nature," he said, "is a curious thing. Fortunately for Readers Digest, most people have plenty of it."

ow, there is a thought worth having, and I heard it first from a passenger in Row Thirteen.

"One more thing," he hastened to add, "the second letter from a disgruntled reader tends to be shorter than the first."

"How about the third?" I ask.

The older man's eyes twinkled. "It is just one sentence -- "

" 'Cancel my subscription!' " I exclaimed.

The man from Readers Digest shrugged. "And, of course, it always gets the correct response."

The two of us laughed again, then sat in silence for awhile, nodding.

"Not all real-time systems are so forgiving," I said.

"Talking about real-time," said Mr. Chapman, "reminds me of my short career as a mechanic repairing line-casting machines."

The seat-belt sign came on.

"Once I put in the wrong-sized spring. We dumped liquid lead all over the composing room floor. 'Stop the presses!' Then there was this other time..."

Mr. Chapman and I never returned to the subject of elevators and the grumble factor. And the SVP.

or airline passengers, 'the grumble factor' comes with the boarding pass. Sometimes even if you're in Row Thirteen. Consider, for example, a certain steely-eyed brain-truster I met once. It was on an American 'red-eye' to New York. We buckled in and shook hands.  His card, which bore the American Airlines logo, gave the man's department as "Terminal Operations." I chuckled in spite of myself. "Sounds ominous, Brian."

He didn't smile. Brian was in his middle thirties, a few years my senior. He solemnly explained to me that 'terminal' means 'airport.' OK, so my theory about Row Thirteen doesn't always work out. Could be that Brian was indeed superstitious too, but, as an employee of the airline on standby status, he simply got assigned to Row Thirteen.

Brian told me he worked at corporate headquarters where his staff had recently completed a nationwide study of the company's baggage handling systems.

"Baggage handling must be interesting," said I, suppressing a yawn.

"Airlines sell speed," he said. "Convenience, too. But speed is the main product."

"Something like elevators," I said. Brian looked perplexed at my trivial comparison. "You must be a marketing guy," I said. "Let me guess: Harvard MBA?"

"Statistician, Dartmouth," Brian answered with a frown. "The actual flying is only part of the overall trip time. Terminal operations account for the rest."

"You were about to describe some kind of study," said I. There's little hope for this guy.

"Passenger tolerance is a competitive issue," said Brian.

Here is somebody else concerned about 'the grumble factor.' This was much like the elevator business, damn it, and I said so. I told Brian about P. T. Barton, the guy with the bow-tie and the mysterious 'SVP'.  I posed the question about how to save elevator shafts and Brian immediately held up his hand.

"That's simple," said he. I was sure he was bluffing.

The flight attendant brought reading materials. I selected two, for I commenced to doubt that this conversation had any possibilities.

"Simple, sure," I said.

"Service economics are sensitive to customer tolerance," said Brian. "That's true of hamburgers, car repairs, dry cleaners -- yes, and elevators."

I nodded knowingly. "Like waiting at the ticket counter. You probably use queueing theory to reduce the average delay."

Brian shook his head. "Average delay in delivering baggage at the end of the flight -- that's much more important."

"Is that why you prefer carry-on?" I asked.

Brian ignored my impertinence. " 'Average', by the way, "is but one measure of 'central tendency.' You can drown in a lake the average depth of which is one foot."

"Sure," I said trying to keep up, "you're going to tell me about 'standard deviation' and, um,..."

"Good, I don't have to explain 'skewedness' and 'peakedness,' do I."

"'Peakedness?" I asked.

"Ever hear of a 'bimodal distribution'?" The man was annoyed with me, I could tell.

"That must be when you have two peaks. Like two averages, or something."

Brian grimaced. "There's that word again. The distribution of student-heights in a typical classroom would be bimodal," he explained obviously not for the first time.

"Co-educational classroom, you mean." I could see that Brian was not in the mood for banter and sobered up my face.

"Remember, the average American has -- "

" -- one tit and one ball," I interjected. "Excuse me," I grinned. "At Dartmouth, they probably say 'one breast and one testicle'."

"The question American Airlines faced with was: How long are passengers willing wait for their luggage?"

ll I could do was shrug.

"Naturally," said he, "you can't just ask them. Passengers would surely say, 'Have my luggage waiting for me when I get to the baggage claim area.' Yet, a system capable of instantaneous delivery would be uneconomic as hell."

To find the answer, Brian told me that he and his staff decided to conduct a surreptitious experiment. He gestured expansively. "At all major airports, on selected flights, we arranged to have the baggage secretly withheld."

Brian allowed me time to register disbelief.

"Withheld," he added, "until the first passenger complained."

Guided by Brian's staff at headquarters, American Airlines enlisted managers at each terminal to make clandestine measurements of the interval between when the plane arrived at the gate and the first passenger complained. Baggage and suitcases would then be released -- allowed to flow along the conveyers and to slide onto the carousels to be claimed.

While Brian was talking, the flight attendant brought us snacks and soft drinks. I munched in silence, giving contemplation to the spectre of hapless passengers grouped around baggage carousels all over the country -- unwitting subjects in a secret experiment to quantify 'the grumble factor'.

"In statistical work," Brian said professorially, "you must always start out with an hypothesis."

"What was yours?" asked I on cue.

Brian pulled a pen from his pocket and drew a bell-shaped curve on his napkin. "We expected to see something like this -- a distribution of time intervals, peaked at about 45 minutes."

"Before the first complaint," I mused. "Reasonable enough."

"That was our hypothesis. What we got was..." Brian modified the sketch with a second curve.

"Hmm," I hmmed.  "Bimodal."

Brian marked a time-scale underneath. "These two distinct lumps were about 20 minutes apart." He shoved the napkin toward me. "It was like we were dealing with two distinct populations!"

"Brian, you're saying that one bunch of people started bitching for their baggage after waiting 45 minutes; another -- "

"Another subset of our passengers were willing to stand around for more than an hour!"

"That's gotta be easy to explain, Brian."

"Care to try?"

I thought for a moment. "It has nothing to do with boys and girls, does it."

Brian, ever mirthless, shook his head. "All flights have both sexes."

This guy must think I just fell off a turnip wagon. I'll show him. "My guess is, it's day versus night: Passengers arriving on night flights -- like the one we're on right now -- are less patient than those in the daytime."

Brian sipped his drink. "That was one of the first things my staff thought of, too. They pumped the numbers into the computer -- if the data backed up that theory, we could cut the size of our daytime baggage crews, right? I mean, what's the hurry!"

"I take it, the data didn't, so you couldn't."

"Let me warn you. It's subtle."

"Length of flight, then," I conjectured. "Off hand, I don't know which way it would correlate: whether people on short flights are willing to wait longer or -- "

Brian interrupted my speculation. "No correlation."

I felt my brow furrowing itself, then brightened suddenly. "East versus West!" I exclaimed. "Everybody knows that New Yorkers are impatient and that -- "

The man next to me in Row Thirteen pulled a trade journal from his briefcase, probably Baggage Blaim. By now all sensible passengers on the flight were asleep.

"Let me think about it," I said.

t 35,000 feet, stars do not twinkle. Lights on the ground, even those of moving vehicles, appear stationary. I yawned and wondered what flight crews do to deal with their own version of 'the grumble factor' during long, eventless flights. Pilot boredom can be a safety hazard in the sky, I'll bet.  As our flight crawled through the sky toward Idlewild International Airport, now named JFK, my thoughts softened and tangled. Soon I felt myself descending into the dark, arms heavy at my side. I pulled backwards, retreating through an echoing room, dragging luggage across asphalt tile, crowds of sullen people staring at me, blaming me for hiding their miserable suitcases. "It's all an experiment," I tried to explain.

"Coffee, sir?"

I squinted first at the flight attendant and then into the gray dawn. The stars were gone.

"Landing in New York in 15 minutes," chirped she.

"Figure it out yet?" asked Brian.

I stretched and shook my head.

"Neither did I," he said. "About the elevators, I mean."

I reached down between the seats and pulled on my shoes.

"You told me it was simple," I protested.

"The part about the mirrors at every floor -- I've seen them in hotels across from the elevator doors -- that part was simple," said Brian. "What the hell does 'SVP' stand for?"

A chuckle might have been appropriate but was out of range. Midnight-to-dawn flights do that to me.

"Self-Viewing Pacifier," I said. Brian shrugged. I signalled my desire to take care of a personal imperative. He stood up in the aisle.

Brian was still standing when I returned to Row Thirteen. "We need a name like that for what we found with the baggage system," he said. "What do you think of CP?"

"Which stands for?"

" 'Carousel Pacification' " answered Brian, smiling -- for the first time since boarding.

Brian explained that one of the variables in his baggage-witholding experiment was not controlled. It was the time when the conveyer system was turned on at each airport!

"If the carousel is inadvertently powered up early," Brian told me, "people will simply stand there watching and waiting."

shall be damned, I thought to myself.

A scenario popped into my head: "Patience, my dear. So long as the carousel is turning, something must be happening back there in the baggage area!" Meanwhile, the luggage is nowhere to be seen -- held up by Brian and his co-conspirators, staring solemnly at their stop watches.

"An extra twenty minutes," I mused.

"Without complaining," added the man in Row Thirteen.

"That ought to be worth some big bucks to American Airlines."

Tires outside squealed onto the runway.

In the terminal building, Brian heaved his carry-on bag over one shoulder and shook my hand.

" 'CP' won't do," I grumbled. "Should be a 'TLD'."

Brian looked puzzled.

" 'Triple-Letter Designator' -- like everything else in the space age."

Later that morning, after waiting impassively before an empty carousel, turning, turning, I was able to reflect on the denouement. I shall surely be damned, I again thought.