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Would the pilot ever pitch down (even slightly) during a flight, or would he/she simply reduce power to reduce altitude?

This question is not similar to Why do airplanes lift up their nose to climb? (asked by Chris) for it the reasons aircraft pitch up. This question is looking for an answer that explains if and when a pilot pitches down during a flight to reduce altitude, the very opposite of the question of @Chris.

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  • $\begingroup$ possible duplicate of Why do airplanes lift up their nose to climb? $\endgroup$ – Jan Hudec May 20 '15 at 8:21
  • $\begingroup$ Could you be more specific of what you want to know? I could answer this in several ways and I am not sure which one would give you what you are looking for. $\endgroup$ – GdD May 20 '15 at 8:24
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    $\begingroup$ emergency descent (during decompression or TCAS warning) will have a pitch down. $\endgroup$ – ratchet freak May 20 '15 at 8:24
  • $\begingroup$ @GdD, I was wondering whether the pilot would pitch down under normal circumstances. More specifically, from the beginning of the descent. $\endgroup$ – Madhav Sudarshan May 20 '15 at 8:26
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    $\begingroup$ Well if they pitch up to climb it's only logical that they would eventually pitch back down. $\endgroup$ – fooot May 20 '15 at 16:07
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The most common case to pitch down is to speed up, not to reduce altitude, for example when transitioning from a climb (at climb speed) to level flight (accelerating to cruise speed). You can transition to level flight by reducing thrust, but that'll leave you level at climb speed, and is usually not what you want.

Changing configuration will usually require pitching changes to maintain stable flight. In particular during the approach-to-landing, extending the flaps will substantially increase the drag, and in order to maintain airspeed, you'll need to pitch the nose down. If you don't, you'll bleed off airspeed and potentially eventually stall unless you overpower the drag with thrust.

There are of course unusual circumstances that will require a pitch-down as well, obstacle avoidance for example (e.g. airplanes). As mentioned in the comments, to make a speedy descent you'll probably also want to pitch down (such as in case of pressurization problems or fire on board).

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  • $\begingroup$ The reason you pitch down when deploying flaps is to counter the large increase in lift (the balloon). Every plane with flaps is capable of level dirty flight, otherwise a go-around, requiring a pitch up, would be impossible. When flying a constant AoA approach, the nose does control airspeed, but not because the engines can't maintain airspeed, but to keep the aircraft stable at a given AoA. $\endgroup$ – Rhino Driver May 24 '15 at 3:32
  • $\begingroup$ @RhinoDriver The increased lift comes with increased drag. You're effectively saying the same thing, but you subscribe to the 'pitch controls altitude' point of view. If you use power controls altitude and pitch controls airspeed, then your approach airspeed corresponds to a different pitch attitude with the new configuration. They're both valid and interconnected. I also did not mention level flight, of course you can maintain level flight or even climb with flaps down. I'll remove the 'can' to make it less ambiguous $\endgroup$ – falstro May 24 '15 at 9:52
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I'm going to interpret "normal" as cruise level of a commercial flight. Normal for other types of flying might have different answers.

In level flight pitch is regularly adjusted both up and down to maintain the chosen altitude. Generally these adjustments are small enough that they are not noticed by passengers or crew, especially with an autopilot engaged. So is it very normal to pitch down in small increments without changing power settings.

With larger changes in pitch, for example when descending from cruise level, typically thrust is reduced or increased to maintain airspeed. It would be unusual to pitch down before reducing power, or pitch up before increasing it.

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To add a bit of historical background, the argument used to rage as to whether you should "control altitude with pitch and speed with power" or "control altitude with power and speed with pitch." I always felt (and still do, though I'm long retired) that adhering to a hard line either way was a bit silly. Obviously you can use either to change either, within limitations of course. I don't know what current thinking is on the subject. In the end it's a matter of energy management.

There used to be at least one special case where you would want to change both altitude and speed by using pitch alone for a bit. On the 747-200 with certain engines, when starting a descent from high altitude (like the high 30s up to the max operating altitude), the recommendation was to start the descent by putting the nose down first and waiting until the airspeed started increasing before reducing power, thus avoiding the embarrassment of a possible high altitude flameout. My guess is that with modern engines and FADEC, this kind of thing is no longer an issue.

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Whenever you track a reference in the vertical plane of your aircraft (nose to tail) it requires you to pitch up and down.

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Descending from Class A airspace on approach to an airport, a commercial airliner will, in my experience, often pitch down slightly. It can be somewhat unnerving, especially as the engines will throttle down around the same time, but the nose-down is typically very shallow.

Whether a pilot continues to nose-down on final depends on the aircraft, the airport and the wind conditions. It's often a practical requirement to nose down at the runway in a high crosswind landing, in order to minimize the sideways slip produced by the crosswind as well as to traverse the layer of air containing the crosswind as quickly as possible.

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