Ask the pilot

Why do our red-eye flights always go westbound and not the other way? And why do all flights to Europe depart in the evening and land in the morning?

The red-eye departures leave West Coast cities in the late evening (around 10 or 11 p.m.) and arrive on the East Coast at sunrise. In order to land on the West Coast at sunrise, however, a plane would need to take off from an Eastern city at around 3:30 a.m. There would not be a large market for this service. (Leaving the East Coast at 11 p.m., we'd be landing out West at about 2 a.m. Same story.) It's a function of the time change, and thus it's impossible to run a true red-eye going west in which you depart in the evening and arrive in the morning.

From the United States to Europe, almost all flights are red-eyes because morning landings allow passengers to connect onward. A large number of people are bound for intra-European, African, or Middle Eastern destinations and are merely transiting the first arrival city. After touching down, a plane sits briefly, changes crews and supplies, and then re-crosses the Atlantic, getting back to the States in the afternoon and allowing plenty of time for connections. This system makes for a very effective utilization of the aircraft and is convenient for most passengers.

There are a few daylight flights to Europe. Leaving New York or Boston in the morning, a British Airways flight will get you to London by about 8 p.m.

My flight the other morning was nearly empty. The airlines complain that they make money only when flights are full, so why, when a plane is carrying hardly any people, don't they cancel the flight?

Airplanes don't simply fly back and forth between the same two cities. If a flight from San Diego to Dallas is empty, it can't be canceled without affecting the whole system. That airplane may be destined, later in the day, for Philadelphia or Newark or Miami, or might be needed at a station for maintenance procedures. Every flight is part of a vast puzzle. Hundreds of airplanes are at work simultaneously, and the airlines use complicated algorithms to coordinate them.

Meanwhile, occupancy is not necessarily a good gauge of revenue. In recent months, lower fares have required very high loads (or, to use industry parlance, "load factor") just to break even, but on certain routes even an underbooked flight can still be a profitable one. On international flights, premium fares in first and business class are the moneymakers, while those in coach represent little more than filler. And down below, there are often many thousands of pounds of valuable mail and freight.

A British newspaper recently told the story of a flight forced to divert because the pilot wasn't trained to land in fog. The passengers panicked when the pilot announced that he hadn't been trained. How could this be true?

And several years ago, a flight taxiing for departure in foggy weather returned to the gate and the flight attendant announced, "We apologize, but the pilot does not have enough experience to take off."

Both of these examples (the former case was reported in the U.K. tabloid Sun) involve complicated situations that were taken out of context and dumbed down into preposterous-sounding scenarios.

Runway visibility is measured using something called RVR (runway visual range). A series of light-sensitive machines provide visibility values in feet or meters. When visibility drops below certain parameters, pilots must perform so-called Category 2 or Category 3 approaches. Such conditions happen rarely, and as a result not all airplanes are certified to perform them, and not all pilots are qualified to fly them. In fact, a relatively small number of runways even allow such approaches. In the British case, conditions called for a Category 3 approach. Many airplanes, not just this one, had in all likelihood been forced to divert. (If, during taxi, you spot a strange-looking airport sign that says "Cat II," it's referring to the runway hold-line that airplanes must observe when Category 2 approaches are in progress.)

For departures it works similarly. When takeoff visibility drops to certain levels, the runway, the airplane, and the pilots all must meet various requirements. Our hapless flight attendant was technically correct that her pilot lacked the needed "experience," but summarizing the situation using such simple language was misguided.

I noticed a successive arrangement of signs along the edge of the runway. Each sign featured a single digit, and these went in order: 9, 8, 7, 6, and so on. Is this some kind of distance marking?

Yes, these signs indicate the distance remaining, measured in thousands of feet. If you're departing on a typical 10,000-foot strip, expect to see a 4 or 5 zipping by as you leave the payment. That depends, however. I remember a takeoff once in a 727 from the airport in Cuzco, Peru, high in the Andes. The "2" sign went past my window in a blur while the tires were still firmly on the ground. But don't fret, as takeoff distances are calculated prior to every departure to ensure adequate distance not only for taking off, but for stopping should something occur.

Runway striping can also be used to measure distance, but this usually isn't visible from the cabin. The various signs and markings strewn about the airport can seem baffling to a passenger. The section of the Aeronautical Information Manual covering such markings features 27 pages of diagrams and explanations.

My least favorite part of flying is takeoff. Then, during early climb, the engine thrust is suddenly cut and it feels like the plane is suddenly falling backwards. What is happening here? It seems like a poor time to ease back on thrust.

As I've mentioned, takeoff is the most precarious point of flight. More fingernails are chewed during landings, I suppose, but in deference to the laws of gravity and momentum, this anxiety is somewhat misplaced. If you insist on being nervous, liftoff is your moment. The airplane is making that transition from earth to sky, and its grip on the latter is tentative in those first few seconds. However, even a dying engine should not cause havoc here, as planes are certified for takeoff with a power plant failing at the worst possible moment, but inherently it's the most critical time.

But yes, engine thrust is routinely cut back during the initial climb. The amount used for takeoff itself is, in the interests of safety and performance, more than enough, and so it's lessened once aloft to save wear on the engines. In any case it would be rather impractical to go climbing through ten thousand feet at takeoff thrust. The exact moment of the reduction depends on the airplane and the respective "profile" being flown. The plane is still climbing, don't worry, and is not decelerating nearly as much as it may feel.

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