Ask an Airline Pilot

Have questions you want to ask an airline pilot but don’t have one handy? Or you notice that they’re busy with pre-flight duties (thanks for noticing and for not interfering) so you don’t say anything?

Here are the questions I get asked most often, with the best answers I can come up with:

1. Do personal electronic devices interfere with aircraft systems?

Answer: Here’s what you have remember about aircraft systems and electronic devices. First, many handheld or personal devices create an electronic signal, particularly if they have a cord of some type. Aircraft systems are constantly seeking out specific electronic signals from everything from Global Positioning Satellites to ground-based antennae for communications and navigation.

Further, even within the aircraft, there are electronics creating and transmitting electronic signals between systems for both navigation and control of other aircraft systems–including flight controls. It’s important that only the required signals are received by specific on-board systems and yes, extraneous electronic impulses can interfere with those required for control of various navigation and control functions.

Most have backups with non-electronic signals. For example, on the 737-800, the engines are controlled by an advanced solid-state dual system we call EECs. For every throttle movement, the EEC computers are sending impulses to the fuel control based on hundreds of minute electronic inputs from computers, sensors, instrumentation, and pre-programmed performance parameters. Worst case, though, if there is an interference problem or a failure, the system reverts to a “dumb” mode, simply using the old direct throttle and hydro-mechanical linkage. So in this case, any electronic interference is not a major problem–just an inefficiency.

Ditto in the approach mode: the aircraft navigation systems are receiving and displaying course and altitude data from ground-based antennae. If there’s a conflict or interference, we simply don’t use the data. That only changes the minimum descent altitude which again, is an efficiency issue: might have to divert if we can’t descend below the weather.

A final and more important consideration is in play though, when it comes to personal handheld devices during critical phases of flight. That is, the personal attention of the passengers–which needs to be directed to the crew. Not watching a video, or typing a text message, or listening to music. In critical phases of flight, passengers need to focus on and attend to the instructions of the crew.

2. How fast are we going on take-off and landing?

Answer: Well, it varies based on aircraft weight and flap configuration, but you can pretty much figure in a large jetliner that both the take-off and touchdown speed will be between 130 and 155 miles per hour (of course we use nautical miles per hour for our calculations). The jet will normally fly about ten knots shy of the computed take-off speed, but that is a minimum that doesn’t ensure maneuvering speed margins.

Speeds on takeoff and landing are always a spectrum of choices for the pilots. On take-off, we consider the climb gradient required due to obstacles or terrain ahead. More flaps offers a higher climb gradient and a lower take-off speed. A lower flap setting requires more runway for take-off but most likely can allow for a reduced power setting, important points for engine life and even noise considerations.

The short runway at Santa Ana's John Wayne Airport is always a performance challenge for both take-off and landing.

On landing, the higher flap setting allows for a slower approach speed, which is key when landing on a short runway. An interesting point you may not realize is that by design, the profile speeds for the stretched aircraft like the 737, 757 and 777 are artificially boosted to keep the nose position relatively low through both the take-off and landing rotations. That’s because the geometry of the stretched fuselage leaves a critically small margin between the tail and the runway on both maneuvers: in the 757, you have about 18 inches between the tailcone and the runway on take-off rotation and landing flare–not really much clearance. The higher approach speeds keep the nose lower.

Of course, upon landing on a short field like Santa Ana or even Washington Reagan or LaGuardia, the last thing you want is excess speed to absorb in stopping. No worries though: Boeing has given us the toughest landing gear and brakes in the air today.

3. Are most landings done by automation?

Answer: No. In fact, very few are, for a couple of good reasons. First, the ground based antenna must be kept free of any obstructions, and that specification and guarantee is only provided in very low visibility, which in itself is unusual. I mean that literally too: the airport physically ensures that no ground traffic of any kind–airport vehicles or aircraft–taxies by the antenna while an aircraft  is using the signal for landing guidance.

If the antenna isn’t specifically certified as free from any interference, the landing will not be automatic. Also, a special crew certification is required for autoland, and not all aircraft are equipped to do it: MD-80s, 757s, 767s and 777s  can all autoland if the correct conditions exist. But the 737-800 I fly does not have the capability to autoland. Rather, we have the cosmic Heads Up Display that allows me, the captain, to land with no ceiling and only 300 feet of forward visibility:

I can “see” the runway through whatever weather shrouds the actual runway–because the GPS system synthesizes a runway which exactly overlays the actual runway and I’m watching it all the way down. So at least in the 737-800’s I fly, you’ll never have an autoland and will always have a hand-flown approach and landing. And even when I flew the autoland-capable MD-80, I’d perform maybe one or two actual autolands per year. So the answer, generally speaking, is no, aircraft aren’t normally landed “automatically.”

Whatever the visibility, the Boeing-737-800 at my airline is landed by hand.

The last question that goes with the group of “most asked” I won’t even answer, and I usually don’t when inevitably, someone has to ask: “Where is the   nearest bathroom?” The answer is, “I’ve answered the important questions above–I’ll leave this one up to you.”


23 Responses to “Ask an Airline Pilot”

  1. Shikhar Joshi Says:

    Hi Chris! Nice blog 🙂
    Agreed that most of the landings you do are not automated but just a question, the plane aligns itself with the runway with the help of computers right? If not, then how do you actually align it with the runway?
    P.S : I’m an aspiring pilot from India, 17 years old 🙂

    • Actually no, the plane doesn’t align itself with the runway. The pilot must do that: either manually by intercepting the correct (and correctly tuned and identified) course guidance, flying inbound on a radial, or visually–that is, lining up based on seeing the runway. The autopilot can intercept the inbound radial if the pilot sets it up right and engages the mode. But the aircraft never doesn’t do anything “on its own.”

  2. Shikhar Joshi Says:

    Ohk! Thanks 🙂

  3. That snow photo makes me cringe! Thanks for all you do, Captain!

  4. Lego Spaceman Says:

    Do any of your co pilots say anything about pictures of the backs of their heads showing up on your blog?

  5. Here’s a question I always though of:

    Why do the bev carts need to be built of steel (or whatever heavy material). Wouldn’t the cart itself be a source of weight that would be good to get rid of? Also while we’re at it, why not just have an electronic menu then the F/As can just pass out via trays. Not sure if that’s a time saver but would be a weight saver.

    • The carts are made of as lightweight a material as can endure the beating they take both in flight and in the catering process both in and out of the plane.

      The only menus we ever see are in First Class, but they’re really not a weight consideration. In coach, it’s just a matter of choosing a beverage or whatever snack you want to buy.

  6. The carts look heavy but I guess they are made of the lightweight material. Usually as I sit for hours in Coach, I am looking around for ways to save on weight. Thanks for the reply. I love your blog!

  7. Chris

    Great post. I just wanted to thank you for the effort in putting together the podcasts….the topics and guests are great and I have found myself re-listening to quite a few of those, so please keep it up.

    Heard your thoughts about the AF447 report on the Airplanegeeks podcast, very interesting.

    It would be cool to have an Airbus pilot on the blog to discuss the different approaches to the flight interface sometime, as long as nobody comes to blows it would be very informative…


    • That’s a great idea–I will check with a few folks I know who fly the big Airbus and set up a discussion for a future podcast.

      Thanks for the suggestion and stay tuned!

  8. Cool! Great pictures, too. thanks

  9. Cedarglen Says:

    I’m late Chris, but thanks for another great post. I don’t think that I’ve ever asked a uniformed person for directions to a restroom and in your honor, I promise to never do so. I CAN read the signs, or guess, just as well as you can. To be frank, I’m not a fan of the audio blogs. They do seem to cut into your usual written work. The audio seems to be of mixed quality, the music-over is annoying and getting the content is too slow for me. (Most people read at least three times as fast as most other speak, so its also a time thing.) still, it is a fun expeiment. If you are getting other, more positive feedback, go for it! And heck yes, I’m still reading. Stand by for a question about that HUD shot in a moment. Best wishes, -C.

    • Glad to have you back. I get what you’re saying about the podcast. It’s probably best to think of the podcast as a whole separate endeavor–but I do get what you mean by the music, I’m actually sick of it too. BTW, Miss Giulia’s husband Mike graciously did the outro portion.

      What’s really squeezing my time is not the podcast, though, it’s “TDD,” or “The Damn Dissertation” which is eating up my time: I’m on a short leash to finish the writing portion this semester (400 pages and counting) to defend in the spring. But I realize that once I’m done, I’ll have all of that time back for other things.

      Coming up on the podcast I have author Mark Berent, writer of _Rolling Thunder_, _Steel Tiger_, _Phantom Leader_, and _Storm Flight_, a series based on his real life flying as a fighter pilot in Vietnam.

      His voice, like Ed Rasimus’s (another fighter jock with 250 combat missions and 3 books to his credit), plus Bee Haydu–it’s just kind of a personal passion of mine to preserve and archive these important aviation stories.

      And I’m sure the recce discussion is a narrowly appreciated subject but again, Ed Flanagan is as much a teacher as an aviator and an engineer and even a historian. I know, it’s an acquired taste. But I really like having all these aviators tell their stories in their own words.

      • Cedarglen Says:

        Oh yes. I’d forgotten about the dissert! That comes first. WHen f inished, it will make one hech of a great blog post. -C.

      • Cedarglen Says:

        A late addition: I’ve never been away, Chris. Simple fact is that I don’t comment unless there is something to say. I get the notifications about all new posts and I read them. -C.

  10. Cedarglen Says:

    Nice shot of the HUD on your 73? I understand what it is, but I’ve never seen a live one. During a landing approach for example, is the HUD’s data presented and focused such that you can read it clearly while still focusing your eyes on the distant runway? Or, do the eyes still have to accommodate between near and distant vision? I recognize that just being able to keep you head pointed in one direction – forward, and not having to scan multiple panel instruments is a very good thing, but I do not understand how the eye responds to these data. If one wears corrective lenses, perhaps distant and near bifocals, does the HUD user need to make the slight shift when changing attention between the runway (distant) and the HUD data (near)? Can the pilot reall see both clearly at the same time, or is it still a back and forth thing? I hope that I’ve explained that clearly enough to be understood. Best Regards, -C.

    (–There is a slight error in the email address entered with my prior reply. I hope that it does not much up your system. This one is correct.)

    • The HUD doesn’t seem to require any shifting back and forth between vision fields and it’s designed to have lined-up markers if you’re on speed and descent rate so you’re actually only having to line up symmetry with your peripheral vision. The runway it creates seems like a neon overlay of the actual runway once you break out or reach 50′ so there’s no shifting there.

      The symbolic info is easy to pick up but the numeric and letters–not so much. But the semiotic data, the symbols, are all you need in critical situations.

      I really like the HUD: excellent crosscheck with little effort and no shifting between inside and outside.

      • Cedarglen Says:

        Thanks. Wow. The HUD seems to provide far more than I expected. Thanks for the details. -C.

  11. Does the transponder have anything to do with Navigation in a 767 or7 57?

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