I won’t say that people were impressed, exactly, to run across an airline pilot slogging it out with the rest of the commuters, but I was at least unusual. And I was young enough — still in my mid-20s when I bought my first monthly pass for the Boston subway — to seem something of a novelty.

But lately, the looks and glances have changed. The precise meaning of these new-style stares is something I can’t quite fathom. But they are different, full of some strange uneasiness. Is it sympathy? Is it appreciation, respect for a job and responsibility? Or are people merely happy not to be in my polished black shoes, having to deal daily with the pageant of chaos and automatic weaponry we’ve come to find in our airport terminals?

The news these days is brimming with stories that in some way touch the lives of pilots: discussions about the armoring of cockpit doors, the controversy about arming pilots with guns, the danger of bombs hidden in suitcases.

And all of us saw the videos of two stolen planes crashing into skyscrapers, something a pilot had no choice but to take, well, personally.

Four on-duty crews — eight qualified flight officers — were victims of last September’s skyjackings. They were disrespected in the worst way, killed after their beloved machines were stolen from under them and driven into buildings. I didn’t know them, never met any of them. John Ogonowski comes to mind, the good-guy captain of the first crashed airplane. Of all the millions of people who would, in the end, be appalled and mesmerized by the happenings of that day, and of the thousands who would be victimized, Captain Ogonowski was, in a way, the first of them. He lived near here; his funeral made the front page, where he was eulogized for his work with Cambodian immigrants.

But while it would be annoyingly melodramatic to say I felt a bond or kinship with these eight men, there’s an underlying — and wrenching — empathy I cannot avoid. I can understand, maybe, what it must have been like. I can imagine it. For the rest of you, if you’ve never worked in the cathode-ray glow of an airliner cockpit, you won’t quite get it.

What brought Ogonowski and the others to the world of flying jetliners I can’t say, though I assume their stories are similar to mine, harking back to that nugget of boyhood fascination you always seem to discover among pilots, including myself. In the fifth grade I could point out the difference between a 727-100 and a 727-200 from the far side of the tarmac.

Whether I consider myself more, or less, cerebral about flying than most pilots is open to debate. My obsession as a youngster was — and remains — with workings of the airlines themselves. I have no fascination with the sky. I feel no ecstatic glee at the breaking of any “surly bonds.” In junior high I would pore over the system maps of Pan Am, Aeroflot, and Lufthansa, memorizing the names of the foreign capitals they flew to, then drawing up my own imaginary airlines and tracing out their intended routes.

It was all about far-off countries and cultures, and I’d imagine flying to whichever of them at the controls of my favorite airplane, the majestic 747, flagship of the world’s fleets. The sight of a Piper Cub meant nothing to me. Five minutes at an air show watching the Thunderbirds do barrel rolls and I was bored to tears.

Whenever the topic of my job comes up, one of the questions I’m asked is: Aren’t you ever scared? This always has struck me as both a profound and completely asinine question. “Yes,” I answer. “Of course I am scared. I am always scared. And I’d be nervous flying with any pilot who wasn’t scared.” You can take that with the wink it deserves, but it contains an important, if obvious, element of truth.

And people often wonder what the single most difficult and stressful aspect of a pilot’s job really is, a question I can only answer in the negative. I can’t tell you what the hardest part is, for there are lots of them. But I can tell you what the easiest part is. The easiest part of being a pilot is flying the airplane. And I don’t mean that in a swaggering, “Top Gun” sort of way.

The hard part of the job — the other side — rests in the peripherals. This is the stuff of divorce and high blood pressure: short layovers in noisy hotels, 45-minute waits for a shuttle bus on an icy sidewalk, long stretches away from home. And, for those of us who commute, sometimes thousands of miles, to our company-designated “domiciles,” there’s the constant schlepping through terminals with 40 pounds of gear, hoping to catch a standby seat on the next overbooked departure. Finally reaching the flight deck, strapped into the four-point harness of a cockpit seat, a pilot feels about as much stress as in front of the TV or kicked back in a favorite chair.

Exaggeration? Of course. A pilot’s job, after all, is the management of pure contingency. Fires, explosions, physics gone bad, all the nasty scenarios the simulator instructors love so much. It’s all there, coiled beneath the instrument panel, waiting to spring — theoretically, at least, in a game of comfortable, but never comfortable enough, odds. And the pilot’s role is to spring right back.

I sit in front of my instrument panel — a wall of dials and switches, all arranged in a perfect working sequence, with a collective purpose nothing short of mechanical infallibility. Green lights, red lights, blue lights, circular windows with quivering white needles. I slide back my seat and consider it all, with all the criticism and respect an artist might give to his canvas. In that moment I am a maestro of ordered technology.

But if only you could see what lurks behind that console. The maintenance people sometimes rip the panels off to make repairs, and trust me, there’s chaos back there — huge, wildly knotted bundles of wires and cables, like a spaghetti factory has exploded. Most people have never looked into the guts of an airplane, at the hideous blocks of machinery combining to fool gravity (at least until you run out of fuel or hit something). Hydraulic pumps are grinding, stressed metal is moaning and pulling itself apart. That is, it’s all working perfectly, though it sometimes feels less like we’re flying than merely hurtling accidentally through the sky, screaming in for a kill like some colossal bird of prey.

Do pilots think about crashing? Of course they do.

In an interview years ago, the novelist Kurt Vonnegut was asked how he’d like to die. And most of us, I suppose, occasionally play out our own deaths in line with some exciting script. “In a plane crash on Mount Kilimanjaro” was Vonnegut’s answer. And if you think about it, there’s something evocative about that — a jet getting lost in the fog, smacking into the side of that big Tanzanian mountain. Is it the Kilimanjaro part or the plane crash part? Or both?

You’d be hard pressed to find people who think of airplane crashes as anything but the cold hard triumph of gravity over some hulking contraption, but frankly, there’s a certain mystique to some of them. Not a morbid, bloody mystique, but something romantic. Don’t miss the point. It’s not the violence that makes the difference — the ascending G-forces or the body count. The mystique is a contextual thing — the event as a whole, and as we come to see it in retrospect. Not just plane crashes, but all disasters. If the Titanic sinking hadn’t had a mystique about it, it wouldn’t have been a blockbuster love story 80 years later. A boat hits an iceberg and 1,200 people die — and somehow we make a love story out of the wreckage?

Some nightmares have it, some don’t. Pan Am 103 had it over Lockerbie. ValuJet in the Everglades did not. Auschwitz had it. Rwanda did not. Pompeii had it. Hurricane Andrew did not. Sometimes there’s mystique, and sometimes there’s nothing but the pitiful tackiness of violent death. And none of this, of course, means a damn thing to the people who die.

Which brings us to the post-Sept. 11 mind of the pilot, and how our usual anxieties have been supplanted by something more brutal and sinister, something bigger than the tangible betrayals and failures of our machinery.

I was deadheading on a flight from Boston’s Logan airport, en route to Florida, on the Tuesday morning when everything happened. Because of a “security issue,” our captain told us about halfway through the flight, we would be diverting immediately to Charleston, South Carolina. Pilots are polished pros when it comes to dishing out semi-comforting euphemisms, and this little gem would, in time, be one of the more laughable understatements I shall ever hear a comrade utter.

It wasn’t until I joined a large crowd of passengers, some of whom had their hands covering their mouths, in one of the concourse restaurants in Charleston that I learned what was going on. Dan Rather says: “The World Trade Center has collapsed.”

Had the airplanes crashed, blown up, and reduced the upper floors of those buildings to burned-out hulks, the whole event would nonetheless have clung to the realm of believability. But it was the groaning implosion, the buildings dropping, and the white clouds of wreckage funneling like a pyroclastic tornado through the canyonlike streets of lower Manhattan that catapulted the event from a disaster to an event of pure, historical infamy. The sight of those ugly, magnificent towers collapsing onto themselves is the most sublimely terrifying thing I have ever seen in my life.

And in that very moment, I knew that something about the business of flying planes had changed for good. Pilots, like firemen, policemen, FBI agents, and everyone else whose livelihood has been touched, even tangentially, by the events of that day, were destined to take things a bit more to heart.

So people ask me now, “What is different?” Maybe I’m more philosophical than many of my peers, but I haven’t measured a change by any quantifiable means: security, cockpit doors, baggage screening, and the like. It’s something intangible, something that can’t be armored, upgraded, or fenced in by razor wire. It’s a state of mind, a state of unease and disappointment and, to some extent, anger. Anger to have had our industry taken advantage of so ruthlessly, our beautiful planes so brazenly stolen, our co-workers fooled and killed, thousands more thrown out of work.

The ineffable aside, however, what drives it home for pilots are the same pains and inconveniences now faced by passengers everywhere: long lines, chaos at the metal detectors, angst and fear in the terminals. Flying was enough of a hassle before September.

Today, at the same security checkpoint through which I passed the morning of 9/11, you’ll find a showcase of excess. The guards now wear paramilitary style uniforms, complete with hideous gold shoulder braids, combat boots and berets. Across their backs it says SECURITY in bold yellow lettering. But the too-sharp creases in the pantlegs, the cheap fabrics and the lipstick, all belie the phoniness and desperation of the scene. These aren’t even the trappings of a Third World nation — something you’d see at an airport in Quito or Entebbe. This is a carnival imitation of one.

“Take your shoes off, please.” Thank you, Richard Reid, who marched his explosive feet past the guards at normally button-down Charles de Gaulle. What is next? Body cavity searches? At the risk of sounding flip, I can’t help thinking of the movie “Brazil,” Terry Gilliam’s 1985 film about a totalitarian state under a constant barrage of terrorist bombings, brought to the brink of both collapse and hilarity by its own foolish, hyperextended authority.

The paramilitary troopers are cracking jokes; bags are toppling from the X-ray belt, a National Guardsman is flirting with a group of teenage girls. This is supposed to look like the ordered efficiency you’d encounter at Heathrow, Frankfurt or Amsterdam. Instead it feels like a set from Saturday Night Live. The uniforms of “Worldwide Security” are straight from an old Monty Python wardrobe. I feel ashamed, embarrassed that it has come to this. Is this the new world of flying?

It would be hyperbole of the worst order to speak of lost innocence or the world being changed forever. But yes, flying is different now. As with the fallout from any trauma, we hope the more uncomfortable — and unnecessary — aspects of this difference are reckoned with in time.

It will take a while, I suppose, for things to settle and reach whatever state of permanence they are destined for. In the meantime, pilots try hard to maintain standards of professionalism and safety in an environment running a gamut from justified apprehension to outright silliness. Like the rest of you, we were cast into a fray we never wanted a part of.

There are any number of things the airlines could do to preclude this. And one of these cannot be implemented fast enough: the long-needed installation of an inexpensive piece of equipment into the communications radios of airliners. While we fuss over cockpit doors, bombs and preflight security, this simple enhancement could save hundreds of lives.

The culprit is something called a “heterodyne.” No, it’s not a prehistoric animal or newly discovered subatomic particle, but the technical term for the phenomenon of two simultaneous radio transmissions blocking each other out.

Normally, flights communicate with air traffic control (ATC) via two-way VHF radios. While tuned to a particular frequency (the spectrum used by air traffic rests between 118.0 and 136.97 MHz), a pilot or controller clicks the microphone, speaks and waits for an acknowledgment or “readback.” It differs from talking on the telephone, for example, as only one party can speak at a time.

The trouble arises when two — or more — microphones are clicked at the same instant. The transmissions are effectively canceled out, rendered unintelligible in a noisy hail of static or a high-pitched squeal. Speaking simultaneously, the transmitting parties do not realize the block has occurred.

Airspace in and around major terminals is often congested with planes, all receiving and acknowledging instructions in rapid-fire succession. Blocked transmissions are very common. Anyone with a scanner or receiver that picks up the air traffic bands will be treated to the piercing squeals of heterodynes, often followed by third-party pilots chirping in with “You were blocked,” or “You were stepped on,” so that the instruction or acknowledgment can be repeated.

When maneuvering through the skies and along taxiways, pilots listen not only for their own instructions, but for those of other pilots as well. By creating a mental picture of what other aircraft are doing, they can orient themselves in the vast choreography of a crowded sky or tarmac. Should anybody offer an incorrect readback, acknowledge the wrong clearance or otherwise screw up, other pilots often detect the mistake.

Even in the worst congestion, such errors are rare and dangerous ones even more so. But the potential is always there, and the stakes are much higher than a heterodyne-induced headache or having to repeat yourself.

And sadly enough, the lesson here is not so much of what could happen, but what has already happened. For this month marks the 25th anniversary of the world’s worst air disaster, a crash between two airplanes that never left the ground, caused in part by a blocked transmission, a heterodyne. Most people have never heard of Tenerife, a small, frying pan-shaped speck in the Atlantic. Tenerife is one of the Canary Islands, a rocky chain off the coast of Morocco, governed by the Spanish. The big town on Tenerife is called Santa Cruz, and its airport, at the base of a cascading mountain, is called Los Rodeos. On March 27, 1977, Los Rodeos was the scene of the worst airplane crash in history.

On that Sunday afternoon, just before 2 p.m., two Boeing 747s touched down at Los Rodeos. One was a KLM (Royal Dutch Airlines) flight from Amsterdam. The other a Pan American flight from New York. Both were charter flights.

And neither, as fate would have it, was supposed to be on Tenerife at all. Both were originally headed to nearby Las Palmas, where their passengers, nearly 700 in all, were meeting cruise ships bound for the Mediterranean. But earlier in the afternoon, a bomb exploded in a flower shop at Las Palmas airport, and all flights were diverted. Both KLM and Pan Am, along with many others, put down on Tenerife until Las Palmas opened up again.

They taxied to the terminal building, parking right next to each other on the tarmac. It was a hectic scene at the normally lazy Los Rodeos. The ramp was crammed with airplanes — most of which weren’t scheduled to be there in the first place. Jet engines whined, horns blared, cars and trucks darted between aircraft and beneath wingtips.

At just about 5 o’clock, with Las Palmas accepting traffic and the airplanes refueled, the Pan Am and KLM crews received taxi clearance and began to move. Meanwhile, the weather had become terrible, with thick fog, light rain and very little visibility.

The Pan Am jet, in a note of historical irony worth mentioning, was identified on its blue-and-white hull as the Clipper Victor. The doomed Victor was already, in fact, no stranger to notoriety. Seven years earlier this very same airplane made history when it completed the first revenue flight of a Boeing 747, from New York to Heathrow on Jan. 21, 1970. Somewhere on its nose was the dent from a shattered champagne bottle.

>From Clipper Victor, the view from the upper-deck cockpit, some 40 feet above the ground, was a commanding one, high enough for Capt. Victor Grubbs and his crew to see over the roof of the terminal, and above the tails of the other airplanes. Except for one: the KLM 747, which carried the name Rhine.

As the oldest operating airline in the world, KLM was and remains a proud airline with an excellent safety record. In the captain’s seat of the Rhine sat Jacob van Zanten, one of the company’s top instructor pilots. Frequent fliers may have recognized van Zanten’s handsome visage as he walked through the concourse, or down the spiral staircase in the first-class cabin of the 747, for van Zanten himself stared out from some of KLM’s advertisements — in his captain’s seat, silver-haired and square-jawed, assuring the world of the punctuality and competence of his country’s national airline.

Because of the congestion, the normal route to Runway 30 at Los Rodeos was blocked. Departing planes would have to taxi on the runway itself, in a procedure called a “backtaxi.” Reaching the end of the strip, they’d make a 180-degree turn and then take off in the opposite direction.

Both KLM and Pan Am were given permission to backtaxi simultaneously. Van Zanten would go first. He would steer to the end, wheel his 747 around in a great U-turn, and then hold in position until granted permission for takeoff. Behind him was Capt. Grubbs in the Pan Am Clipper. His instructions were to eventually turn clear of the runway to allow van Zanten’s departure.

Because of the fog, the airplanes could not see one another. And neither was visible from the control tower. The airport was not equipped with ground tracking radar.

Finally in position for departure, the KLM crew called for its ATC route clearance. This is not a takeoff clearance, but a procedure outlining turns, altitudes and frequencies for use en route. It is normally received well before an aircraft reaches the runway, but the KLM crew had been too preoccupied with checklists and taxi instructions to ask for it until now.

At 5:06, the KLM first officer, sitting just to the right of van Zanten, verified the route clearance with the control tower. He then uttered these mysterious words: “We are now, uh, at takeoff.”

For whatever reason, the KLM crew believed it had been cleared for takeoff. “We gaan,” van Zanten told his crew. “Let’s go.” Releasing the brakes of his mammoth machine, the Rhine began barreling down the fog-shrouded runway, completely without permission.

“We are now at takeoff” is not standard phraseology among pilots, its intent perhaps vague. But it was explicit enough to get the attention of both the Pan Am crew and the control tower.

Almost immediately, the tower radioed back to KLM, saying, “OK, stand by for takeoff. I will call you.”

At the same time, the Pan Am crew, still on the runway and quite concerned with KLM’s final remark, made a call as well. “And we’re still taxiing down the runway,” announced the first officer.

Either of these transmissions would have been, should have been, enough to stop van Zanten cold in his tracks. Realizing his mistake, there was still time to discontinue the roll. That is, if he’d heard either one.

But because both the controller’s and Pan Am’s calls were made at the same instant, the only audible sound in van Zanten’s ears was the crackle and squeal of a five-second heterodyne.

Further confusion arose as the KLM 747 accelerated. The second officer leaned to van Zanten and asked, “Is he not clear, that Pan American?”

“Oh yes,” van Zanten replied emphatically.

Capt. Grubbs is heard saying nervously, “Let’s get the fuck out of here.” And with that, he and the crew saw the lights of the lumbering KLM jet emerging out of the fog. “Get off! Get off! Get off!” yelled the first officer.

Seconds before impact, van Zanten shouts and attempts to leapfrog his aircraft over the Pan Am, dragging its tail along the pavement for 70 feet. Its landing gear just lifting from the pavement, the Rhine slams into the side of the Clipper Victor, which had veered sharply to the left to avoid the collision.

The KLM aircraft settled back to the runway, skidded another thousand feet and was consumed by fire before a single one of its 248 passengers and crew members could escape. Gutted by fire and explosion, 335 people aboard the Pan Am plane also were killed. (There were 54 survivors from the Pan Am, including the entire cockpit crew.) The combined total of 583 victims represents the highest-ever death toll in an airplane crash of any kind.

Rarely is the heterodyne discussed as a central factor in what happened that day in 1977. Instead, the crux of the event is lost in a quarter-century-long legacy of human factors analysis: The pilots were stressed and tired. They used incorrect terminology. The tower controller was distracted by a soccer game playing in the background. And so forth.

Sure, if van Zanten hadn’t initiated his takeoff roll without permission, nobody would have died that day. But since when have we left our fate entirely in the hands of one person’s judgment? If that were the case, there’d be fewer dials, alarms and flashing red lights in a cockpit. People make stupid mistakes, and technology is supposed to be there to back us up. There are products for sale than can greatly lessen — even eliminate — the danger from most occluded radio calls. These products are cheap, effective and readily available. Added to an aircraft’s communication system, the devices monitor VHF channels and inhibit a pilot or controller from speaking onto an already busy frequency.

Worldwide, some airlines have voluntarily equipped their fleets with such units, the most common of which is made by British Aerospace and trademarked as CONTRAN. One airline, Britannia, a large U.K. operator of 757s and 767s, began outfitting its planes with CONTRAN in 1999. Virgin Atlantic also volunteered to test it on some of its 747s. A ground-based CONTRAN for ATC was put into operation at several British airports.

But despite their fiscally precarious positions, and even with their reputations on the line, it is doubtful the rest our biggest airlines will follow the likes of Britannia and Virgin. Sensible as it may seem, it rarely ever happens this way. Instead, the industry will need some coaching and persuasion from the FAA, its best friend and/or worst enemy, depending on the issue or whom you ask.

While the use of anti-blocking units like CONTRAN is recommended and encouraged by authorities both in the U.S. and abroad (the FAA, the U.K.’s CAA, etc.), it is not mandatory. Not until this technology is required aboard all commerical aircraft will frequencies remain clear of heterodynes and their potential dangers.

In the past, the FAA has eventually gotten around to legislating a host of important regulations after various accidents. After two high-profile midair collisions, one in 1978 and a second in 1986, an airborne traffic collision avoidance system, known as TCAS, is now found in the cockpit of every airliner. Following the crash of ValuJet in the Everglades in 1996, fire suppression was mandated for cargo holds. And after a long pathology of something euphemistically called CFIT, or, “controlled flight into terrain,” ground proximity warning systems (GPWS) became standard equipment.

Generally, not only were these fixes mandated long after they should have been, but they came in the form of expensive, overly complex warning systems. Things like GPWS and TCAS probably thrilled the engineers who designed them, but their color-coded depictions, variable-pitch aural warnings and multistage alarms often use up more gray matter than a pilot may have to spare in the heat of battle.

This time what’s needed is not another acronymic “system” of high-technology prowess, but a back-to-basics, low-tech solution to an old and very high-stakes problem. The fix is so low-tech, in fact, the airlines and regulators should be ashamed and embarrassed even to debate the matter.

In some instances, serious problems do not require cumbersome or costly solutions. It’s too late for those killed on Tenerife, but 25 years later, another clipped transmission could find us back on a foggy runway asking, “Why?”

American Flight 587, en route from JFK to Santo Domingo, Dominican Republic, crashed moments after takeoff when, to put it coarsely but accurately, the tail fell off. Why this happened is not known, but the more investigators learn about Flight 587, the more its rudder is coming under scrutiny. The rudder is the large moveable surface attached to an aircraft’s tail, controlling side-to-side movement, or yawing, along the plane’s vertical axis.

The newest evidence suggests that extreme movements of the rudder, caused either by malfunction or induced inadvertently by the crew, may have stressed the entire tail to the point of failure, possibly with help from a small crack in the tail’s composite structure, which had formed years ago but was heretofore undetected. Black box analysis shows marked oscillations of Flight 587′s rudder prior to the crash. Whether these oscillations were the reason for the fatal tail separation, or merely a symptom of a greater malfunction, is under study, as is the theory that a structural weakness — inherent or otherwise — was exacerbated by an encounter with the wake of a 747 the Airbus was following.

The Allied Pilots Association (APA), which is the collective bargaining agent for American Airlines pilots, has not endorsed its members’ outcry. After the initial petition, opinions have simmered but little progress has been made toward an actual grounding of the fleet. However, follow-up discoveries of rudder and tail problems on other A300s have rekindled unease.

An American A300 discontinued a flight from Miami to Caracas, Venezuela, when it experienced erratic fishtailing after takeoff. The captain returned to Miami and the airplane was examined. The following day, the fishtailing occurred again. American insists there is no connection between the Caracas flight and the crash of Flight 587, but nonetheless it took the jet out of service for more serious examination.

Another American A300 returned to Lima, Peru, just after departure, for a nearly identical problem. Control units from both rudders were sent to Europe for analysis by their manufacturer.

And most recently, a bent actuator rod was found in the rudder of a Federal Express A300 during a routine check at the carrier’s hub in Memphis. This is considered a highly unusual discovery. Federal Aviation Administration officials were sent to determine if any connection could be made between the damaged actuator and what befell Flight 587.

But what does this seeming pathology really indicate? In the aftermath of air crashes, there is often a rush to judgment over what appear to be latent dangers in our flying machines.

“Are we completely comfortable putting our friends and family on an A300?” the petition at American asked. “If the answer to that question is not a resounding yes, then logic would lead a well-trained pilot to conclude that no one should be flying on them either.”

That friends and family invocation is something pilots frequently employ when making a point about safety. If a pilot balks, the inference goes, at loading his mother or best friend aboard an airplane, then he must have a point.

Almost never, however, do the pilots put themselves into the equation. While we shouldn’t slight such a chivalric and respectful gesture from our polyester-clad professionals, it might be a more jarring statement if the pilot, not just his loved one, were missing from the guinea pig seat. But examples of pilots — at least en masse — refusing to fly airplanes are extremely rare.

And, frankly, for good reason. We needn’t launch into statistical rigmarole to illustrate the remarkable safety record of commercial flying, and even in these times of daredevil skyjackings and en route angst, not even the most brazen Vegas renegade would put so much as a nickel on the odds of a plane going down. Delving into the specifics of particular airplane types, not a whole lot changes. This or that model of airliner is occasionally cited as having “one of the best safety records.” But when the stats are boiled down, every commercial airliner out there can make essentially the same boast, including, yes, the A300. Which is safest among all that are safe? When crashes are measured in the single digits, out of millions of departures each year, one or two unfortunate coincidences can throw a misleading spin on the résumé of a certain Airbus or Boeing.

But just because we are safe doesn’t mean we cannot be safer. And while not outright refusing to fly their A300s, and perhaps giving Granny or a next-door neighbor the grudging go-ahead as well, the American pilots have legitimate concerns about November’s disaster. Whether or not those concerns justify a grounding is another matter, but their nervousness is well-taken. As I’m sure the worried pilots are aware, the forced grounding of airplanes is not unprecedented.

On May 25, 1979, an American Airlines DC-10 crashed on takeoff at Chicago’s O’Hare Airport. It was later determined that a crack in an engine pylon, where the plane’s giant turbofans are bolted to the wing, had caused separation of the engine during the takeoff roll. Detached, the power plant bounced across the wing, causing serious damage to flight controls and subsequent loss of the aircraft. The 273 fatalities that sunny afternoon still represent the all-time worst aviation disaster on U.S. soil. And when, in the weeks that followed, additional cracks were discovered in more DC-10s, the FAA ordered the temporary grounding of the entire DC-10 fleet. American, United and Northwest were all major operators of the type. Even foreign carriers were not allowed to bring their DC-10s into the United States.

More recently, the crash of an Air France Concorde in July 2000 was linked to the layout of the aircraft’s fuel tanks. The plane had struck debris on the runway, and an exploding tire caused a tank to rupture. European authorities — the British Civil Aviation Authority and the Direction Generale de L’aviation Civile or DGAC, of France — revoked Concorde’s airworthiness certificate, and it remained grounded for 15 months.

It has been more than 20 years, however, since the DC-10 fiasco. And the entire Concorde fleet involved barely a dozen aircraft carrying an extremely limited — and exclusive — share of the world’s passengers. Some will argue the system does not always react with the best interest of the traveling public in mind. The FAA has long been accused of employing a tombstone mentality, submitting to the economic concerns of airlines until some post-disaster fallout forces it to do otherwise. Critics — and perhaps cynics — will refer to the saga of the Boeing 737, an effectively ongoing case study of an allegedly defective aircraft allowed to fly.

There are almost 4,000 737s operating today throughout the world, and the aircraft — a small, twin-engine narrow-body — is the bestselling jetliner of all time. But the 737 was aloft for years with a known rudder problem. This problem is believed to have caused at least two fatal accidents: the 1994 crash of a USAir flight near Pittsburgh in which 132 people died, and a United flight at Colorado Springs in 1991 that killed 25. At least two nonfatal incidents occurred as well, in which aircraft became nearly uncontrollable when the rudder malfunctioned during flight.

Beginning in 1996, the National Transportation Safety Board (NTSB), which independently investigates accidents before forwarding recommendations to the FAA, requested no fewer than 22 changes be made to the 737 rudder. Eventually the FAA ordered the complete redesign of the rudder’s control units, and today all U.S.-registered 737s have been modified. But the aircraft was never grounded. The safety enhancements were applied over time, progressively, while the FAA, Boeing and the airlines worked together to solve the problem.

The FAA, which postures as the altruistic vanguard of the skies, will be loath to admit it, but in truth there is not, nor will there be, a zero-tolerance policy when it comes to air safety. There is, uncomfortable as the flying public might be with the idea, an allowable level of jeopardy, an acceptable threshold of disaster. The risks are quite small, but they do exist.

In the story of the 737, a sensible, risk-evaluated approach seems to have worked. While the needed upgrades were being hashed out, there were no additional accidents. The FAA took that chance. And they will likely take it again in the matter of the A300.

Call it a gamble if you will, but such is the example in many aspects of life, where threats are calculated and plotted, and disasters, while avoided at great cost, are both anticipated and accepted. The FAA has dragged its feet at times (cargo compartment fire protection), wasted its efforts on smokescreen issues (pilot drug testing), and blatantly pandered to industry on others (crew rest/duty time regulations). But to its credit, the agency also works hard to keep the numbers strongly in your favor, albeit with some needed prodding, often by pilot unions.

American is the only current operator of passenger-carrying A300s in the United States. FedEx and UPS fly them as freighters, and DHL flies a cargo version of an older model. But the grounding of any aircraft type, whether common like the 737 or rare like the A300, is not as simple as recalling a Ford Pinto. Neither is it statistically warranted, usually.

The American pilots cite the lack of a known cause of the Flight 587 disaster in their challenge to ground the A300. We cannot fault their agitation, but a single unsolved (so far) accident does not warrant grounding. Further, there is inadequate evidence linking the more recent A300 incidents with November’s crash. With regard to the Caracas and Lima flights, American blames engine surging, not an erratic rudder.

In a first step, regulators are urging airlines to enhance their pilot training programs, recommending they now include procedures to avoid rapid or extreme rudder deflections. “Rudder inputs by pilots can cause catastrophic failure,” said NTSB Chairman Marion Blakey. “Full rudder inputs can jeopardize the safety of a vertical tail fin.” Pilots will chuckle at the idea of being dragged back to class to learn what is already patently obvious, as a pilot pushing a rudder to full-scale deflection is no different from a driver on the highway suddenly yanking the steering wheel 90 degrees. What many pilots may not be aware of, however, is exactly how sensitive a particular rudder’s control units are to a pilot’s inputs in a specific regime of flight. For now, with little else to go on, a little extra work in the simulator certainly can’t hurt.

But pilots and passengers alike should realize that the uncertainty surrounding the A300 does not, by itself, point to a likelihood of dangerous tails waiting to snap off. Airbus and its customers should — and must — devise a way to further ensure integrity of its aircraft, but remember that even more proven hazards have not raised such pilot ire in the past, nor were they cause for widespread concern or apprehension. Consider again the 737, or, for that matter, the explosions of empty fuel tanks aboard at least three aircraft, one of which caused the infamous destruction of TWA Flight 800 in 1996. Planes occasionally crash and will continue to do so.

The annals of commercial aviation — more or less an 80-year history — are full of inexplicable accidents, a fact, however frustrating, inherent in the evolution of technology and safety. We should learn to be more comfortable with this. For in spite of such mysteries, the statistics remain firmly on your side, by a wide enough margin that none of us should be dissuaded from taking to the skies in virtually any airliner.

Our most cherished activity, though, was gaining access to the airplanes themselves, something we did routinely and with hardly a suspicious glance from guards or employees. We would pass through security and stake out the gate of an arriving flight. Then we’d ask an agent or crew member if we could take a peek at the cockpit. Or, more daringly, when all passengers had disembarked, we would simply walk down the enclosure and step aboard unseen. On some occasions we were told to go ahead, unsupervised, often by the captain himself: “Just don’t monkey around with anything.”

We would roam the cockpits and aisles, helping ourselves to cans of soda, magazines, passenger briefing cards, playing cards — whatever souvenirs we wanted. At the very least, cordial captains would give us tours, both inside and out, of all our favorite planes. Once, as eighth-graders, two friends and I spent more than a full hour in the cockpit of one major airline’s DC-10 parked at the gate, utterly unbeknownst to a single person besides us. Finally a mechanic came aboard for a routine check and found us in the pilots’ chairs, seat belts on, pretending to be airborne over the Atlantic somewhere.

This was the late 1970s. The threat of terrorism, mind you, was not some nascent fear in people’s minds, but as real and frequent a phenomenon then as today, if not more so. For the sake of precedent, one might recall that on a single day in September 1970, four New York-bound passenger jets were hijacked simultaneously by Palestinian terrorists and blown up (albeit after the release of the passengers).

Our memories seem unfortunately short, outrage not brought on until fireballs and a high death count are televised. Now, in the wake of the sad death of 15-year-old Charles Bishop, the student pilot who, just last week, stole a single-engine Cessna and flew it into the side of a Tampa skyscraper, a new round of outrage and furor has erupted, this time over an apparent lack of security in the low-profile, low-security world of general aviation. The incident, with its eerie copycat blueprint of the September attacks, has some people reeling, calling for the tightening of airspace restrictions and the battening down of small-town airfields.

Did you know there are 600,000 licensed pilots in the United States? Did you know there are thousands of small airplanes housed at thousands of small airports across the country, many of which are flyable by novices with little skill or experience? And many of these are tied down on unsecured grass fields, their engines startable with the flip of a switch. Not even a key is required. Do we ground them all? Do we station the National Guard at small, single-runway airstrips around the nation?

There’s a beautiful — and perhaps instructive — element of poetic futility to the idea of securing the very air above our heads. Some are proposing cockpit technology that would make it impossible to fly airliners into restricted and prohibited airspace. Another suggestion is to make jets landable by remote control in the event of a hijacking. Perhaps we can string enormous nets over our cities, military bases and power plants, the way London proposed protecting itself from Nazi bombardment during the Blitz.

Let us stop instead, and catch our breaths.

There are lessons and examples from the past that could have taught us something.

In December of 1987 a Pacific Southwest Airlines jet on its way to San Francisco crashed, killing everyone onboard. It was later determined that a recently fired employee, David Burke, used his airline credentials to bypass security with a loaded gun and board the doomed flight. En route, he gained access to the cockpit and shot both pilots and himself, the latter after aiming the plane toward the ground in a vertical dive.

In October 1999, Air Botswana Captain Chris Phatswe commandeered an otherwise empty ATR commuter plane and slammed it into two other parked aircraft, killing himself and destroying virtually the entire fleet of his nation’s tiny airline.

On April 7, 1994, an off-duty Federal Express employee, Auburn Calloway, boarded one of his company’s DC-10s at Memphis armed with a hammer and a spear gun. Riding along as an auxiliary crew member, Calloway attacked the three-man crew after takeoff for Los Angeles, nearly killing all of them. His plan, before finally being overpowered by the battered and bloodied pilots, all of whom were critically injured, was to crash the huge airliner into FedEx’s Memphis sorting hub.

And in the early morning hours of Sept. 12, 1994, crack-addled pilot Frank Eugene Corder flew his Cessna into the side of the White House.

Surely these events represented a breakdown of security on some level and were paid a sad homage by the September skyjackers, who seemingly borrowed a little bit of strategy from each. What have we learned? What do we do?

The truth is, however, there is only so much we can or should do. Not until now has the public demanded a top-to-bottom overhaul of the system, but hysteria has knocked effectiveness out of the picture. Nobody will argue that improvements are not needed, but somewhere a line must be drawn, and we must come to our senses over what is useful security, and what is not.

Our priorities, for now at least, are misplaced and irrational. In the cockpit after Sept. 11, any pilot will tell you the conversations were all about knives and box cutters. And the cockpit door was once the hottest topic in town — how to make it stronger, how to make it bulletproof, how to make it unopenable to anyone without a jackhammer. It was rare — and remains so — to hear pilots discussing the danger of bombs and explosives in the luggage bins down below. We ignore the reality that the likelihood of another kamikaze-style attack is tiny, while the threat of explosives is much, much greater.

Then on Dec. 21, 2001, Richard Reid climbs aboard a 767 with a bomb in his sneakers. We are shocked. How did we miss this? Reid’s flight, mind you, departed on the 13th anniversary of the bombing of Pan Am 103 over Lockerbie, a vicious irony that, like recollection of the Pan Am event as a whole, was scarcely mentioned in the press. It’s interesting to note that when ground casualties are excluded, more people died that night in 1988 over Scotland than were aboard the World Trade Center, Pentagon and Pennsylvania aircraft combined. It remains the single worst incident of terrorism against a civilian American vessel of any kind. But then, not a single coherent program of airport security emerged after Lockerbie in the United States. In Europe, methods of passenger and bag matching and routine explosives screening were put in place. But domestically, nothing. After Reid’s failed sneaker bomb, suddenly we find ourselves scrambling, the airlines and FAA in a panic over the idea of stealthily stashed explosives.

The immediate response to Reid? Passengers are asked to remove their shoes prior to screening. At the risk of sounding flip, dare it be suggested that strip searches or body-cavity probes are to follow? A smart terrorist will see that sneakers are out, and what’s more fiendish than a bomb inside a body?

One important irony, of course, is that Reid boarded his flight at Charles de Gaulle in Paris, an airport, like most major terminals of Western Europe, known for excellent security and equipped with all the fancy equipment for sniffing out explosives. Which brings us to what is perhaps the most important lesson to be dug — whether we face up to it today or years from now — from the rubble of Manhattan: No system is, or will ever be, foolproof.

We will, hopefully before the next bombing, buy and operate better, more widespread explosives screening equipment. Will it be 100 percent effective? No, not nearly. But statistically we will be safer, and far less pained by the makeshift procedures and ludicrous mayhem found at the airport today, something airlines are beginning to measure economically as, in the words of one airline executive, “hassle factor.” And in the meantime, let’s not humiliate the traveling public by asking people to take off their footwear and tiptoe barefoot through the metal detectors.

In an atmosphere charged with trauma, we’ve come to view security as a phenomenon of pure cause-and-effect, which is at heart both dangerous and distracting. With, it seems, little sense of history or perspective, we view every follow-up event, from the mundane to the serious, as evidence of some glaring weakness in our already overstressed system. Whether a routine breach at the X-ray scanner or a disturbed man with a shoe bomb, the cry is to bolt more doors, deny more access, call out more soldiers. Lost in the outcry is the realization that incidents of terror are just as likely the inevitable work of statistics and politics as they are examples of carelessness or incompetence.

Some of the results are just plain sad. Observation decks are locked up tight, rooftop parking lots closed off. Airliner buffs are shooed away from perimeter fences where they once gathered to plane spot, just as I did as a youngster. Even the act of photographing a jetliner from a concourse window is now banned in many places, a policy you would have found in Moscow or Bucharest a generation ago. Are the airports safer because of this? No, not really.

And, as many pilots will lament, gone perhaps forever is one of the single greatest flying experiences in the world, the “Governor’s Island Departure” from Newark International Airport, by which commuter planes once zipped northbound up the edge of the Hudson River, wings seemingly scraping the upper floors of the Manhattan skyscrapers. After taking off from Newark’s Runway 22, we’d make a sharp left turn directly toward the World Trade Center before. That familiar view of the twin towers growing larger in the windshield of my turboprop is something I’ll always remember. And it is, doubtless, the very same view Mohammed Atta and some of his conspirators had seconds before impact.

Our biggest mistake has been to declare yet another policy of zero tolerance. But something as inherently dangerous as flying will never be made inherently safe. As we attempt the impossible, especially in the heat of panic, we do so at our own peril, all the while turning our airports into stages of absurd comedy while inconveniencing millions of travelers, many of whom might be laughing if it weren’t for the delays and nervous stares from young Guardsmen with automatic weapons.

In reality, all the locked doors, sneaker checks and get-tough promises in the world will not stop somebody who is hellbent on destroying an airliner. Further, the events of Sept. 11 were not the result of a breakdown within the jurisdictions of airport security. Had the airplanes been bombed it would be a different story, but as it happened, it was not a crime to step aboard those aircraft with box cutters. To address what went wrong that day, we need to examine the landscapes of politics and immigration and the oversight of individuals with terrorist links. We needn’t scapegoat airport workers, the FAA or anybody who wears the uniform of any of our nation’s air carriers. Had box cutters been banned aboard aircraft that morning, which they were not, Atta and his men, clever and determined, probably would have found another way.

And just as the war on drugs will never completely eliminate the supply of illicit narcotics, the war on terror will not eliminate the supply of angry radicals or otherwise dangerous airline passengers. Reasonable, effective security, in conjunction with longer-term programs beyond the realm of aviation itself, will be our best bets for the future. It’s time to make the move from panic to process.

In the past 24 hours no fewer than four times have I fielded questions about whether the crash of American Airlines Flight 587 might involve some kind of government coverup. The scenario goes like this: A bomb destroyed the plane, and the government, along with the airlines, fearing paralysis of the economy and our collective psyche in the wake of recent events, has decided to play off the crash as an accident. “Turbulence,” they are saying. And while no, those men in dark suits and sunglasses (I know because I saw them on “The X-Files”) dont have screenwriting credentials, cant they do better than that? I mean, come on, after all, turbulence cant bring down a 150-ton airliner.

Except that it can.

There are, in fact, different causes and kinds of turbulence, a phenomenon that is no less inherent a part of the sky than, say, clouds or a balmy summer breeze. Collectively speaking, turbulence is no more or less dangerous than the wind itself. As a pilot, I worry about “turbulence” the way a sailor might worry about “the waves.” But when we talk turbulence with respect to Mondays crash, put away your notions about that “Please fasten your seatbelt, theres some rough air ahead” kind of chop-chop-chop that whirlpools your coffee or causes you to miss a stroke or two on your laptop. This is something different.

Investigators are now focusing on something known to pilots as “wake turbulence.” When a plane is heavy and traveling at a relatively slow speed, as would normally be the case just after takeoff, the steep deck angle required to maintain lift helps propagate a kind of twin-forking roil of air that trails behind the aircraft like an invisible wake from a ship. Two vortexes, one from each wingtip, are spun away like sideways tornadoes. The vortexes then begin a slow descent, and their counterrotations cause them to diverge slightly. Picture, if you will, two long, violent fingers of air protruding from the back of an airliner like a forked, downward-sloping tail. When moisture levels are high enough, the cores of these spinning currents, which can reach velocities of 300 feet per second, become visible, shooting from the wings as thin strands of condensed vapor.

Whether taking off, landing or cruising straight ahead, the vortexes are always there, but their strength becomes exacerbated under certain combinations of aircraft speed, weight and deck angle. Atmospheric conditions, meanwhile, particularly wind, can alter, break apart or dissipate a vortex before its ever encountered. Thus, flying in windy, bumpy (yes, turbulent) air, can actually be one of the best conditions for avoiding this kind of trouble. There also are procedures, rules and recommendations that all commercial pilots are familiar with. Air Traffic Control, for example, is required to separate aircraft in accordance with parameters of both distance and time, and pilots are trained to use climb and descent gradients that put them out of harms way.

But every pilot has, at one time or another, had a run-in with a wake, whether it be the short bump-and-roll from a dying, vestigial vortex, or a grab-your-armrest, full-force wrestling match. They usually last, at the most, a few seconds. I remember once, on a calm foggy night, standing along a seawall in South Boston less than a mile from where the tires of approaching planes screech against the asphalt of Logan Internationals Runway 04R. Each passing jet was followed about 30 seconds later by an eerie snapping of air that sounded as if a giant leather whip was being struck over the harbor. These were the sideways tornadoes, touching down around me. And once, as the captain of a 19-seat commuter plane landing at Philadelphia, my aircraft was knocked and rolled wildly just a few hundred feet above the ground. It felt like wed hit some Grade 6 whitewater in a rubber raft. The culprit: a Boeing 757 that arrived a few minutes earlier. The 757, owing to aerodynamic idiosyncrasy, is suspected of producing a particularly virile brand of wake.

But it wasnt a Boeing 757 that American 587 followed out of JFK on Monday morning, it was its much bigger brother, the 747, the largest commercial plane ever built, in the livery of Japan Airlines and bound nonstop for Tokyo with a full load of fuel. It weighed about 800,000 pounds. It was heavy, slow and climbing. The American A300, about half its size, was following closely behind and beneath. Ahead of it, the JAL 747 was spinning its invisible tornadoes like a huge, red-and-white spider. Did American somehow creep too close?

Maybe. Nobody knows for sure. And if so, still, could the wake have been powerful enough to destroy the tail of Flight 587, or snap off those truck-size GE turbofans? Smaller — much smaller — aircraft have crashed as the result of wake turbulence. Only this past summer a 10-passenger Cessna in the colors of Cape Air skidded across a runway at Boston after, it is believed, being kicked upside down by just such an encounter. But never a large jet. Never an A300.

When it all shakes out, though, it seems there are never any nevers when it comes to aviation disasters. From lightning strikes to wings falling off — yes its happened, even if only once. Its worth noting, too, that in 1994 this very same plane, which wore the tail registration N10453, made an unscheduled landing in the Caribbean after an inflight knock-around when it struck some rather rough air at 35,000 feet. Could this incident have resulted in a structural weakness, cracks or fatigue, that was heretofore undetected, and needed only the right set of circumstances to manifest itself tragically? Its possible. In 1985, in the second-worst air disaster in history, a JAL 747, ironically enough, crashed near Mt. Fuji when an aft pressure bulkhead ruptured. A rush of air from the passenger compartment surged into the unpressurized tail, knocking away part of the rudder and severing hydraulic lines. It was later discovered that a hard landing and faulty repairs, made some seven years earlier, had left the bulkhead vulnerable.

But if the big American Airbus fell victim to an unusual and unprecedented event, I suspect it found its way, as so many crashed planes have, to that one-in-a-million convergence of “ifs.” Two hundred and sixty-five people suddenly won the lottery they never wanted to win.

Flying is inherently dangerous, and will always be so. But also, as the statistics show, it is the least dangerous of all our tried-and-true ways of getting around. The unfortunate end of American 587 will not skew the numbers. In fact, neither Mohammed Atta and his henchman, nor all the wake turbulence and bad luck in the world, will likely change a thing.