Re: Korean Air 801 crashed on approach to Guam

Date:         08 Aug 97 05:41:20 
From:         Phil Wood <woodp@netgate.net>
Organization: AeroMarketing Associates (http://www.aeromarketing.com)
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jf mezei wrote:

> Could someone put this missing glide slope in perspective ?

"Missing" is probably not the right work. It was out of order and so
stated. In pilot-speak, it was NOTAM (notice to airman) out of service.

When the glideslope part of an approach is out of service, the approach
reverts to a localizer-only approach. It requires a little bit more
pilot effort when hand-flying, but not significantly more. It certainly
wouldn't "overwhelm" even a begining IFR pilot.

A localizer approach provides just directional information lined up
directly to the runway.  Alltitude step-downs occur at either fixed time
or distance increments until you reach a minimum descent hight. If you
see the runway, land - If not, go around.  Under no circumstances can
you go below the minimum.  Obviously, KAL801 violated that rule.

> 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 ?

A full ILS usully brings the aircraft down to 200 ft above the runway
before teh pilot either has to land or abort.  LOC approaches are higher
(typically 300-600) - there are many factors which determine the minimum
descent altitude (obstacle clearance, missed approach considerations,
runway length, lighting, etc.)

> Is it plausible that the missing glide slope would have resulted in the
> plane being much lower than it should have been in its approach ?

One of the requirements for descending below MDA is to have the runway
environment in sight - either lights, runway or something.  KAL801
crahsed 3 miles from the airport with less than three miles visibility.
>From the reports, that sounds like a NO-NO.

> How common is it for the glide slope to be inoperational for airports
> that handle 747s on a daily basis ? Is this a no-brainer for pilots when
> it is missing, or does this require a lot more attention ?

Not uncommon - GS and LOC require maintenance like anything else.  And
they are but only two of the many instrument approach methods - I'd
rather shoot an ILS over a LOC, but if the GS is out, a LOC is almost as
easy.

The tough ones (in my opinion) are NDBs - That's what was in use at
Dubrovnik when Sec. Brown went down.
--
     Phil Wood                                  woodp@netgate.net
                                        73717.3453@compuserve.com
                                    Philip.Wood@sv.sc.philips.com
     <a href = "http://www.aeromarketing.com/woodp">Phil Wood</a>