Misleading Notam

"Roy Smith" wrote in message
...
"Gary L. Drescher" wrote:
A hundredth-degree change in descent angle is
(barely) perceptible on the ASI or VSI.

I'd like to see a pilot or VSI which can notice the difference between
500 fpm and 502 fpm.

You're right, it would have been more accurate for me to say a *few*
hundredths of a degree. But that still justifies more than one decimal
place of precision. A few hundredths of a degree change of descent angle
moves the VSI needle almost as much as a one-degree heading change moves the
HI (and courses are routinely specified with single-degree precision).

--Gary

Just to avoid potential confusion, the NOTAM has been reworded to include
"Vertical Descent Angle" in front of 3.52 degrees. The previous way had been
used for at least 4 years when adding VDA's to non-precision procedures via
NOTAMS, but will probably change now since the old appears to lead to
confusion. Incidentally, the reason this NOTAM was originally created is
that the airport painted new runway numbers (17/35) on the runways due to
magnetic variation updates, and Memphis Approach didn't hear about it until
after the fact.

FDC 3/1417
FI/T GENERAL DEWITT SPAIN, MEMPHIS TN. VOR RWY 16, ORIG... CHANGE ALL
REFERENCES TO RWY 16/34 TO RWY 17/35. ADD: FROM SHLBY TO RW17: VERTICAL
DESCENT ANGLE 3.52 DEGREES, TCH 31. ADD NOTE: VGSI AND DESCENT ANGLES NOT
COINCIDENT.
--

JPH


"Michael" wrote in message
m...
Greg Esres wrote
One of our local pilots misunderstood a common Notam, as shown below.
He thought the "ADD: From Shelby to RW 17: 3.52 degrees" meant add
3.52 degrees to the final approach course.

How reasonable do you think his interpretation?

For someone coversant with TERPS - not very. For someone who meets
the knowledge requirements for the instrument rating but not much more
- pretty reasonable. Note the context - the runway numbers are
changed (increased). I can easily see how someone might think that
this means the final approach course should also be adjusted, and the
direction and magnitude of the adjustment are consistent with the
runway change.

(BTW, the notam just adds a descent gradient to a NP approach.)

FDC 3/0143 M01 FI/T GENERAL DEWITT SPAIN, MEMPHIS, TN. VOR RWY
16, ORIG...CHANGE ALL REFERENCES TO RWY 16/34 TO RWY 17/35.
ADD: FROM SHLBY TO RW 17: 3.52 DEGREES, TCH 31. ADD NOTE: VGSI
AND DESCENT ANGLES NOT COINCIDENT.

Not exactly plain English, is it?

Michael

Just to avoid potential confusion, the NOTAM has been reworded to
include

One of my fellow instructors called the Flight Procedures Quality
control guru and pointed out the possible confusion.