NTSB Preliminary report on HPN crash

Tom Fleischman k wrote
in
news:2005050612522816807%bodhijunkoneeightyeightju nkatmacdotcom@junkjunk:

On 2005-05-06 09:48:46 -0400, "Peter R."
said:

snip
Regardless of who was flying the instructor was doubtless PIC. Now I
know that the Passeur Airport Monitor
(http://www4.passur.com/hpn.html) does not give an officially
recognized altitude readout, but if you set that site to begin on 4/23
at about 16:15 local time you can track the flight. If you compare
their altitude readout to other aircraft flying the same approach it
seems evident that they were below the approach segment altitude even
before they crossed the outer marker. In fact it shows them crossing
HESTR already 100' too low (1900'). I can not fathom what this
instructor was thinking continuing the approach so far below the
glideslope, even after an altitude alert from the tower.
snip

If you go back to about 15:10 and set the window to 20 miles you can pick
him up as low as 1600' just south of Yorktown Heights over 134, which I
believe is inside the FARAN intersection, but clearly outside the Outer
Marker - ie: Minimum Safe Altitude is 2000', and he is 400' low...

It's tough to say how accurate and to-scale the Passur site is, but if you
set the scale to 5 miles and watch as he enters the area, it would imply
that he passed the Outer Marker at around 1200'...

Maybe he was tracking a harmonic?

"Judah" wrote in message
. ..
If you go back to about 15:10 and set the window to 20 miles you can pick
him up as low as 1600' just south of Yorktown Heights over 134, which I
believe is inside the FARAN intersection, but clearly outside the Outer
Marker - ie: Minimum Safe Altitude is 2000', and he is 400' low...

Just a point of terminology--2000' is the minimum altitude there, but it's
not the MSA. The MSA there is 2900', and wouldn't be relevant. (As is often
the case, the FAA has violated a cardinal rule of clear naming: when two
names are similar, the difference between them should reflect the difference
in their meanings. The MSA differs from the minimum altitude not with regard
to being safe, but with regard to applying when off-course.)

It's tough to say how accurate and to-scale the Passur site is, but if you
set the scale to 5 miles and watch as he enters the area, it would imply
that he passed the Outer Marker at around 1200'...

Maybe he was tracking a harmonic?

Is it possible to pick up a false GS a few hundred feet *below* the proper
altitude?

--Gary

"Gary Drescher" wrote in
:

"Judah" wrote in message
. ..

snip

Just a point of terminology--2000' is the minimum altitude there, but
it's not the MSA. The MSA there is 2900', and wouldn't be relevant.
(As is often the case, the FAA has violated a cardinal rule of clear
naming: when two names are similar, the difference between them should
reflect the difference in their meanings. The MSA differs from the
minimum altitude not with regard to being safe, but with regard to
applying when off-course.)


A valid point. The MSA for the northeastern region within 25 NM is
2900', though the published minimum allowable (and presumably safe)
altitude while flying the ILS inside Faran is 2000'. Is there a name for
that published altitude?


snip

Maybe he was tracking a harmonic?

Is it possible to pick up a false GS a few hundred feet *below* the
proper altitude?

According to the document published at

http://afsafety.af.mil/magazine/htdo...8/dontneed.htm

if a heavy was holding inside the ILS Hold Short Line it could generate
interference that could cause the glideslope to fail high or low...

Not really a harmonic, I guess, but apparently a possibility.

"Judah" wrote in message
. ..
"Gary Drescher" wrote in
:
Just a point of terminology--2000' is the minimum altitude there, but
it's not the MSA. The MSA there is 2900', and wouldn't be relevant.
(As is often the case, the FAA has violated a cardinal rule of clear
naming: when two names are similar, the difference between them should
reflect the difference in their meanings. The MSA differs from the
minimum altitude not with regard to being safe, but with regard to
applying when off-course.)

A valid point. The MSA for the northeastern region within 25 NM is
2900', though the published minimum allowable (and presumably safe)
altitude while flying the ILS inside Faran is 2000'. Is there a name for
that published altitude?

The NACO approach-plates legend just calls it the "minimum altitude".

--Gary