Re: Korean Air 801 crashed on approach to Guam

Date:         09 Aug 97 02:28:30 
From: (C. Marin Faure)
Organization: Northwest Nexus Inc.
References:   1 2 3
Followups:    1
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In article <airliners.1997.1717@ohare.Chicago.COM>,
"[non-spam]jfmezei" wrote:

> Karl Swartz wrote:
> > to the crash, which occurred at 2:35 am local time in heavy rain.
> > NTSB chairman James Hall said the glide slope portion of the ILS was
> > not functioning.
> Could someone put this missing glide slope in perspective ?
> Just how important is it to a landing in darkness with little or no
> visibility ? What other instruments/information would have been
> available to the pilot to help him stay on track to the runway ?

Other posts have done a good job describing the function of the ILS and
glide slope.  When I was obtaining my instrument rating at Honolulu
International back in the 1970s, I shot full ILS approaches and
localizer-only appproaches, mostly at night as that proved the easiest
time to schedule lessons.  The Cessna 206 I was flying did not have an
autopilot so all my approaches were flown by hand.  If anything, the
localizer approach was easier as I merely had to descend in steps to
specific altitudes at specific points and then level off until reaching
the next point of descent which was marked either by a marker beacon
(radio signal, not a light) or crossing a VOR (another type of radio
signal).  The rate of descent didn't matter as long as you didn't descend
before reaching the descent point or descend below the next specified
altitude.  The full ILS with glide slope was a little harder (without an
autopilot) simply because you had to maintain a specific rate of descent
throughout the approach.  But both approach types are easily mastered by a
competent student instrument pilot with only a hundred or so hours of
total flight time.

C. Marin Faure
  author, Flying A Floatplane