How would you answ this ATPw question?

[Aviatard]

In comparison to an approach in a moderate headwind, which is an indication of a possible wind shear due to a decreasing headwind when descending on the glide slope?

• Less power is required.
• Higher pitch attitude is required.
• Lower descent rate is required.

It was marked wrong on my exam, and I'm having trouble making sense of it. Am I overlooking something, or is it a poorly worded question?

 

[woutlaw]

A?

If the headwind is decreasing, your groundspeed is increasing, so you'll need to increase the rate of descent to maintain the glideslope.

That'll require less power to maintain the target airspeed.

That being said, those windshear questions always make my brain hurt and I'm probably wrong.

 

[Aviatard]

Good! I'm not alone...

That's what I answered... and it was marked wrong. (Note I said 'marked wrong' and not 'wrong.')

Any other takers care to chime in?

 

[midlifeflyer]

In comparison to an approach in a moderate headwind, which is an indication of a possible wind shear due to a decreasing headwind when descending on the glide slope?

• Less power is required.
• Higher pitch attitude is required.
• Lower descent rate is required.

It was marked wrong on my exam, and I'm having trouble making sense of it. Am I overlooking something, or is it a poorly worded question?

I could be wrong but I think it's an intentionally misdirective question. It starts out talking about flight in a headwind, but that's just a set-up and has nothing to do with the answer. Take out the first part and you have the real question:

==============================
which is an indication of a possible wind shear due to a decreasing headwind when descending on the glide slope?
==============================

It's about front-to-back windshear, not about headwinds.

You should be able to take it from there.

 

[Aviatard]

==============================
which is an indication of a possible wind shear due to a decreasing headwind when descending on the glide slope?
==============================

Okay, taking just the second half of the question (excerpted above): Let's say we are on the glideslope with a 20-kt direct headwind. As the headwind decreases, the same pitch-power will take us above the glideslope, yes?

So there are only two ways (or some combination of the two) to stay on glideslope: 1.) reduce power or 2.) lower the pitch.

(Of course, if we're on the back of the power curve, an increase in pitch will also increase drag and sink rate, but... is there anyone who at the first sign of drifting high on the glideslope will increase pitch straightaway?)

Hope I'm not being too dim.

 

[mushroom]

Frankly I would be in favor of "B."

I think of it in this way: Let's say you are hovering (if that were possible) in a little plane, 172 or the like, into a headwind. Now, if the headwind suddenly went away, what would the plane want to do? Nose down, I would think. So if the headwind decreases on approach, I would think the plane would want to pitch down, necessitating you pulling back on the stick, meaning a higher pitch attitude. Kinda like setting up for MCA or a stall when you're training; you slow down, or create less "headwind" yourself by reducing the power, and to compensate you must increase the pitch attitude to maintain the same altitude.

I could be totally misinformed and thinking about it wrong too, though...

:erm:

 

[Amish RakeFight]

B) Higher pitch attitude.

When you lose your headwind or it decreases, you'll experience a drop in pitch necessitating a high pitch attitude.

The other 2 answers just don't make sense if you lose your headwind.

 

[Aviatard]

makes sense now...

Okay, i think I get it. I was thinking a more gradual loss of headwind, when as midlife suggested, "It's about shear, not headwind."

If I think of it as a near-instantaneous loss of headwind, then the aircraft would indeed pitch down, necessitating an corresponding increase in pitch (and power).

B is the answer that Uncle Sam marks as correct.

Thanks for the replies.

 

[flyer172r]

Let's say you are hovering (if that were possible) in a little plane, 172 or the like, into a headwind.

Oh that's definitely possible.

 

[mushroom]

Yeah, I've done it too. I think it is faster to walk than to fly eastbound in the Columbia River Gorge in a small plane in the wintertime.