March 6, 2015
AN OLD-TIMEY QUESTIONS AND ANSWERS SESSION.
Way, way back in 2002, a column called Ask the Pilot, hosted by yours truly, started running in the online magazine Salon, in which I fielded reader-submitted questions about air travel. (United Airlines later stole my name and began running a stripped-down version of the same thing in its inflight magazine.) It’s a good idea, I think, to touch back now and then on the format that got this venerable enterprise started. It’s Ask the Pilot classic, if you will.
Q: I was on a flight and the emergency hatch next to us made the most awful squealing noise during takeoff and landing. We were told it was nothing to worry about, but needless to say I spent the whole flight a nervous wreck.
What you describe isn’t terribly uncommon. Such sounds are caused by small leaks around the door seal as the plane’s pressurization levels fluctuate (sort of like those that result when you stretch the neck of a balloon as it deflates). It’s noisy but it couldn’t be less dangerous. Tiny air leaks pose no hazard. There’s always a little bit of flexibility built into certain airframe components — there has to be — and this is one result. Usually, after a while, the door will settle into a sweet spot and the sound will stop. A similar thing happens in the cockpit sometimes around the seals of the sliding side windows.
On some aircraft — usually smaller ones — the door seal consists of an inflatable gasket. Occasionally this gasket will burst or deflate, causing a gradual depressurization, which is a big hassle that could result in a diversion (having to fly at a lower altitude means having to burn more fuel). The 19-seaters I used to fly had an inflatable seal around the main boarding door. When it failed, as it did once in a while, it made a hideous noise — a sort of hypersonic flatulence, like a motorcycle roaring through the cabin. It scared the hell out of the people closest to the door, but all in all it was harmless.
Q: We flew from Miami to JFK on an MD-80. The jet is laid out with two seats on one side of the aisle and three on the other. The question came up: does the asymmetric 3/2 configuration cause any kind of imbalance?
No. Even on a smallish plane like the MD-80 series (a derivative of the even older DC-9), the imbalance is less than negligible. In the cabin, longitudinal balance is a lot more important that lateral balance. But even there it tends to be a minor factor — at least on bigger planes, where the weight of passengers makes up a surprisingly small percentage of a plane’s overall weight. As covered in the first chapter of my book, in the case of a fully loaded 747, the weight of 400 passengers plus their luggage accounts for less than 10 percent of the plane’s total weight.
Q: What are the normal climb rate and decent rates for jetliners? I know it probably varies, but as a student pilot I was wondering how steep the average rates are.
Indeed it varies. It varies so much that I’m not sure what answer to give you. Really there’s no such thing as a “normal” climb or descent rate. It depends on the weight of the plane, your altitude, the temperature, how many feet you’re trying to lose or gain, ATC constraints, etc. During cruise, if we have to climb or descend only slightly — say 1,000 or 2,000 feet — I’ll usually set up the autopilot for a mild, 500 foot-per-minute rate. On the other hand, I’ve seen rates as high as 5,000-6,000 feet-per-minute both climbing and descending. In the 757s and 767s that I fly, planes I fly, takeoff and initial climb can be anywhere from 2,000 to 5,000 feet-per-minute, depending on the aircraft weight and what segment of the departure profile you’re flying.
Five thousand feet-per-minute sounds like a lot, but so long as any climb or descent is initiated gradually, with minimal change of g-force, even the steepest rates will be barely detectable from a passenger’s seat-of-the-pants perspective.
Q: How come it feels as if Ryanair pilots land at higher speeds than pilots at other carriers? And Ryanair’s pilots always seem to land hard.
Landing speed isn’t subjective. Approach and landing speeds are determined by weight, wind, and flap setting, and aren’t really negotiable. No airline’s pilots land faster (or slower) than anybody else’s. As to the second part of your question, Ryanair tends to serve smaller, outlying airports that often have shorter, less forgiving runways. The technique when landing on a short runway is to not try and finesse it. A slightly firmer touchdown using less runway is preferable to a smoother touchdown that wastes pavement.
Q: Is it true that airlines always hold out one seat in first class for the pilot? And does that mean if, online, it shows two seats left in first, really there is only one?
Long-haul flights carry extra pilots that work in shifts or in teams. The pilots on their rest break retire to a designated rest area. On some aircraft this means a first or business class seat that is pre-reserved for crew. These seats are considered “booked” just as if a passenger had reserved them. So, if an airline says two seats are open, then yes, two seats are open.
On most bigger planes, though, the crew rest quarters are entirely separate from passenger seating. Typically there are bunks or other accommodations tucked away somewhere — above, below, or on the main passenger deck — and accessible only to the pilots (flight attendants have their own rest quarters located elsewhere). In that case, no, there are no seats held for the pilots.
All of this is separate from crews that might be “deadheading.” That is, pilots or cabin staff who are riding as passengers as part of a repositioning assignment. In this case too, the seats occupied by these employees are blocked ahead of time and will not show up as open inventory.
Q: After landing and taxiing into the apron, we came to a stop a couple of hundred feet from the terminal, shut down the engines, and finally were towed to the gate by a tug-tractor. This seems to be common procedure at many airports. What’s the reason?
Many gates at congested airports are tow-in only. The proximity of ground equipment, vehicles and workers makes it hazardous to maneuver using the engines. Even at low power a jet engine produces a considerable amount of thrust that could easily flip over a baggage container — or a person.
Q: I understand for example that a Boeing 747-400 is the -400 variant of the basic 747 model. But what does it mean when I see a picture of an aircraft and the photographer displays the code 747-430? >
Maximum geek on this one. The second two numbers of the suffix — the “30” in this case — are the customer code. Boeing assigns each airline has its own two-number code. The 30 code (I Googled it) belongs to Lufthansa. All 747-400s sold to Lufthansa are 747-430s. A 777-200 delivered to United Airlines would be a 777-222. And so on. This is to help account for engine type, cabin configuration and other customer-specific options. Even if these planes are subsequently sold to another carrier, the designation remains.
The original 747s, the -100s, were actually 747-121s. The 21 suffix belonged to Pan Am.
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