Stall/spin and ground reference maneuvers

Why are pilots so committed to the idea that they can reliably judge airspeed by looking at the sight picture over the nose? What if the runway tilts up and it is surrounded by hills and trees?

The only time that I bet my life on the sight picture is when I'm on a steep final, I'm holding the air brake at a constant setting, and I'm sure that the glide angle and the touchdown point are stable and unchanging.

If this is in response to one of my posts, you missed the bit where I said "...auxiliary inputs are slipstream noise, one or two glances at the ASI..."

-John, Q3

On Tuesday, March 4, 2014 1:13:49 PM UTC-5, son_of_flubber wrote:
Why are pilots so committed to the idea that they can reliably judge airspeed by looking at the sight picture over the nose? What if the runway tilts up and it is surrounded by hills and trees?

On Tuesday, March 4, 2014 1:30:34 PM UTC-5, John Carlyle wrote:
If this is in response to one of my posts,

Not particularly your post. Many pilots are committed to the primacy of the sight picture at turn to final.

JC wrote:
you missed the bit where I said "...AUXILIARY (ed. caps) inputs are slipstream noise, one or two glances at the ASI..."


My take is that just before entering the turn to final, slipstream noise and ASI (and yaw string) are PRIMARY reliable inputs, and that point sight picture is an unreliable input that is subject to pilot error and visual illusions.

As I got better over time at using the sight picture to estimate pattern speed, I found myself relying on it more and more. My tendency to discount and neglect the primary reliable inputs made me more dangerous.

On Tuesday, March 4, 2014 5:11:02 PM UTC-7, son_of_flubber wrote:
On Tuesday, March 4, 2014 1:30:34 PM UTC-5, John Carlyle wrote:

If this is in response to one of my posts,



Not particularly your post. Many pilots are committed to the primacy of the sight picture at turn to final.



JC wrote:

you missed the bit where I said "...AUXILIARY (ed. caps) inputs are slipstream noise, one or two glances at the ASI..."





My take is that just before entering the turn to final, slipstream noise and ASI (and yaw string) are PRIMARY reliable inputs, and that point sight picture is an unreliable input that is subject to pilot error and visual illusions.



As I got better over time at using the sight picture to estimate pattern speed, I found myself relying on it more and more. My tendency to discount and neglect the primary reliable inputs made me more dangerous.



At low altitude and certainly in mountainous country, the "sight picture" is unreliable. (If your destination airport is in a deep "V" valley, at which rock or tree do you point the nose?) As other posters noted, at low altitude, the apparent horizon seems high so the nose appears too low even when it right. So what does one watch? The answer is a fast repetitive scan of everything. Keep coming back to the airspeed and yaw string every few seconds to note trends but don't linger there more than a second or two.

One important action is to trim the glider so it will tend to remain at the desired pattern airspeed. Sergio's article in the February Soaring where he describes pushing the stick without effect struck me as perfect description of a mis-trimmed glider. If trimmed correctly, just relaxing pressure on the stick will cause a too-high nose to lower itself - you don't have to push.

In fact, teaching pilots to fly with a relaxed grip instead of a "death-grip" on the stick would probably in itself eliminate many stall/spin accidents. A well trimmed glider simply won't spin itself - it takes gross control inputs to make it spin which is more difficult to do with finger tip pressure.

Another very useful skill is semi-instrument flying - controlling pitch attitude with airspeed alone. (It's the airspeed part of "needle, ball airspeed" partial-panel instrument flying.) This involves watching the airspeed trend. If it's trending lower, the nose is too high and if trending higher, the nose is too low. This is something that can be learned in an airplane while doing ground reference maneuvers.

On Tuesday, March 4, 2014 1:13:49 PM UTC-5, son_of_flubber wrote:
Why are pilots so committed to the idea that they can reliably judge airspeed by looking at the sight picture over the nose? What if the runway tilts up and it is surrounded by hills and trees? The only time that I bet my life on the sight picture is when I'm on a steep final, I'm holding the air brake at a constant setting, and I'm sure that the glide angle and the touchdown point are stable and unchanging.

It is not the sight picture itself, it is the change in the sight picture that needs to be noticed.
If you are staring at the wing tip. or the landing target, you likley aren't noticing that you pulled the nose up in the turn or were skidding. Obviously terrain affects the sight picture.
When looking at the nose, a quick eye movement allows the airspeed to be checked for confirmation.
UH

It's not just the view, though with experience you get to recognize rates of
change, there's also sound and control feel. But I think everyone
(including myself) steals the occasional peek at the airspeed indicator as
well.


"son_of_flubber" wrote in message
...
Why are pilots so committed to the idea that they can reliably judge
airspeed by looking at the sight picture over the nose? What if the runway
tilts up and it is surrounded by hills and trees?

The only time that I bet my life on the sight picture is when I'm on a
steep final, I'm holding the air brake at a constant setting, and I'm sure
that the glide angle and the touchdown point are stable and unchanging.

On Tue, 04 Mar 2014 17:45:10 -0700, Dan Marotta wrote:

It's not just the view, though with experience you get to recognize
rates of change, there's also sound and control feel. But I think
everyone (including myself) steals the occasional peek at the airspeed
indicator as well.

Yes, and I like to have the ASI top and centre in the panel because this
way the airfield remains in my peripheral vision when I glance at it.



--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |