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Confused over these questions

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Old 11th Jan 2013, 13:45
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Confused over these questions

I'm close to finishing the HPL ATPL topic now and done a mock exam paper and when I was going over the questions I got wrong, I'm a bit confused by the following questions:

By breathing 100% oxygen a partial pressure of oxygen within the lungs equivalent to MSL can be maintained up to:
A 40000'
B 34000'
C 30000'
D 25000'

The correct answer is B however I chose A. I was sure A was correct as between sea level and 10000' only pure air is required. 10000'-33700' air + o2 supplement is needed. 33700'-40000' 100% pure o2. 40000' and above- pure 02 under pressure. Surly answer A is correct then? Can someone tell me why it's not?

Another question is:

An aircraft accelerating in level flight may result in the pilot sensing: I chose option B which was "Pitch-up , contrary to the indications of an air driven artificial horizon. However the answer in the book is: Pitch-up , supported to the indications of an air driven artificial horizon

Finally the last question was: Errors in application of skill based behavior are most likely to occur to: I said those with no or limited experience. The book said experienced pilots!

I'm a bit confused, can anyone explain?

Thanks
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Old 11th Jan 2013, 14:12
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Question 1: It asks where you can obtain a MSL pressure. I guess at 40,000 feet, using pure o2 only gives say a 8,000ft pressure level? Enough to survive, but not what the question wants? Not sure

Question 2 involves a bit of knowledge about how the air-driven AH works. My hunch would be because it has a COG centered below the gyro (due to pendulous vanes), when you accelerate, the COG lags behind, and precesses the gimble. I believe not only it shows a pitch up,but also a roll to the right.

3, no idea.

Hope that helps a little...
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Old 11th Jan 2013, 14:22
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For 3, I think the logic behind it is that if you have no experience, you won't be applying skill based behaviour, you will be paying specific attention to detail, whereas if you are experience, you will often not focus on the task at hand, do things by rote, etc. and that can lead to errors.

Like driving to work and when you get there you can't remember if you ran a red light or not.
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Old 11th Jan 2013, 14:22
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pic,

I've been teaching this stuff for twenty years and I offer one piece of advice:

Ask the specialist instructor(s) at your school why two answers are incorrect.

Last edited by Lightning Mate; 11th Jan 2013 at 14:22.
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Old 11th Jan 2013, 14:23
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Not only can an air driven ADI show a pitch-up when accelerating, the pilot himself can feel as if he is pitching up when in an accelerating aircraft, especially without outside reference.

That's probably what they mean.
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Old 11th Jan 2013, 14:44
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My more or less educated guesses:

- Providing O2 support at the correct altitude need probably not mean that the oxygen pressure within the lungs remains equivalent to MSL, so maybe at 40,000 ft it is lower than at MSL (although still sufficient)?

- Apparently, suction AIs do indicate a climb when the airplane accelerates: "Acceleration and deceleration also induce precession errors, depending upon the amount and extent of the force applied. During acceleration the horizon bar moves down, indicating a climb." (Source: attitude indicator (artificial horizon))

- Experienced pilots perform their tasks almost automatically, without having to carefully think about what to do (next). This makes them quicker and more efficient in their actions and with more spare mental resources compared to someone inexperienced, but also increases the risk that their "automatic" responses are wrong, for instance when the environment has slightly changed. Some examples can be found, e.g., in Skill-, Rule-, and Knowledge ? Based Behaviours and Associated Errors . It also increases the risk for lack of concentration blunders since the mind prefers to wander around rather than focus on a task that has become routine and dull. In the words of James Reason: "Paradoxically, absent-mindedness is the penalty we pay for being skilled; that is, for being able to run off our routine actions in a largely automatic fashion" (Reason, J., 2008, "The Human Contribution", Farnham: Ashgate, p. 44).
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Old 11th Jan 2013, 18:00
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1st.
They ask for SEA LEVEL.
If you breath 100% ox. with no pressure at 40.000ft, it will correspond to 10.000, not sea level.

2.
air driver AH is subject to acceleration as well, so it may/will show a slight climb when you are accelerating in level flight.

3.
An experienced pilot is less aware of what he is doing, it all automated.
So for an experienced pilot it will be a lot easier to overlook something VS "new" pilot, who is still insecure and very aware of his actions.
You can as well call it "routine errors".
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Old 12th Jan 2013, 07:02
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Skill based learning is done at a very deep level and provides the quickest decision making. Obviously, you need to be experienced in this case.

Rule based is next (when you have to check with the manuals) and Knowledge based is last, where there are no rules or skills to fall back on. These affect less experienced pilots.
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