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?