Today’s Illustration: Misleading Signals

  Flight 801 Crash Ways To Set Up A Crash!

On This Day: August 8, 1997 — approximately 1:00 a.m.  — Flight 801 crashes in Nimitz Hill, killing hundreds!

Korean Air Flight 801 crashes at Nimitz Hill, Guam.   The flight left Kimpo International Airport in Seoul, Korea and was scheduled to land at Won Guam International Airport in Guam.

It was a Boeing 747, manned by two pilots and one flight engineer.  The occupants were 14 flight attendants and 237 passengers.  Most passengers were tourists on their way to vacation in Guam.

It crashed into the dense jungle early Wednesday morning, three miles south of the airport and into the mountain.

The airplane did not crash because of any engine or structural failure.  It was due to pilot error, along with lesser contributing factors which did not and would not have caused the crash, but did contribute to pilot error.

Early speculation was that the pilot miscalculated the approach to the runway, thinking that the guidance beacon on the hilltop was on the runway.  Or, the pilot might have lowered the landing gear far too early, and that would have disabled the alarm system which was designed to warn a pilot that he was too close to the ground.

The captain of flight 801 was a well-qualified pilot who had logged almost 9,000 hours of flight time.  The First Officer has 4,000 hours, and the flight engineer had over 13,000 hours.


The History:

Captain “Park had originally been scheduled to fly to Dubai, United Arab Emirates; since he did not have enough rest for the Dubai trip, he was reassigned to Flight 801.”

The pilot and crew were implementing an instrument landing.

The tower had informed Captain Park that the glideslope (the ILS — instrument landing system ) was out of service

The plane would be relying on the VOR and DME system to navigate and land (see notes for further understanding of those systems).

According to the voice recorder,

Captain To Crew: ”The localizer glideslope is out.”

Tower Repeats: ‘Glide slope unusable.”

Flight Crew: “Roger”  (Acknowledged)

Chief engineer (two minutes before the crash): ”Is the Glideslope working?” Glideslope?  Yeah?

Captain: “Yes, yes, it’s working.”

Someone: ”Check the glide slope if working?”

Someone: “Why is it working?”

First Officer: “Not Usable”

Someone: ”Glide slope is incorrect.”

First Officer: “Approaching 1,400”

Captain: “Since today’s glide slope condition is not good, we need to maintain 1,440 — Please set it.”  (The “setting of it would tell the airplane to not go below 1,400 feet in altitude)

Someone: “yes”

Captain: “look carefully” — “set five hundred sixty feet”

First Officer: “set”

Plane’s landing gear lowered and flaps extended.

Captain: “Isn’t glideslope working?”

The airplane’s automatic announcement system indicates that the plane had descended below 1,000 feet — (12 seconds before the crash)

First officer:  “Runway not in sight.”

Airplane System: “five hundred” –  feet

Flight Engineer: “two hundred” – feet

First Officer:  “let’s make a missed approach.”

Flight Engineer: “not in sight.”

First Officer: “not in sight, missed approach.”

Flight Engineer: “go around.”

Captain: “go around.”

Too Late!


Of the 254 persons on board, 228 were killed, and 23 passengers and 3 flight attendants survived the accident with serious injuries.

One of the surviving passengers indicated that the crash happened so quickly that there was no announcement and there was not even a scream heard by him.

The fuel in the ruptured wings ignited a fire which burned for approximately eight hours.

NTSB Report & Recommendations:  Three of the recommendations from the National Transportation & Safety Board . . . .

Consider designating Guam International Airport as a special airport requiring special pilot qualifications.

Disseminate information to pilots, through the Aeronautical Information Manual, about the possibility of momentary erroneous indications on cockpit displays when the primary signal generator for a ground-based navigational transmitter (for example, a glideslope, VOR, or nondirectional beacon transmitter) is inoperative.  Further, this information should reiterate to pilots that they should disregard any navigation indication, regardless of its apparent validity, if the particular transmitter was identified as unusable or inoperative.

Issue guidance to air carriers to ensure that pilots periodically perform nonprecision approaches during line operations in daytime visual conditions in which such practice would not add a risk factor.

Malcolm Brenner (Black-box specialist and one of the investigators of Flight 801 crash):

“. . . . what the captain seems to be doing is assuming that at some point he’s going to break out of the clouds and see the airport, and he doesn’t see it by five hundred sixty feet, he’ll just go around.  Now, that would work except for one more thing.  The VOR on which he’s basing this strategy is not at the airport.  It’s two-point-five miles away on Nimitz Hill. . . . Sometimes you can follow the VOR down and takes you straight to the airport.  Here if you follow the VOR down, it takes you straight to Nimitz Hill.”

“. . . . it’s one in the morning, and he’d been up since 6 a.m. the previous day . . . . a minor technical malfunction; bad weather; and a tired pilot.”  – Outliers by Malcolm Gladwell — pgs 211-12

The flight and the Guam airport was not new to the Captain.  Captain Park had flown into Guam eight times before.

However, perhaps — just perhaps the crash was due to “culture.”  Well at least as much culture as minor technical problems (which were overcome by other pilots landing 100’s of planes landing throughout the month), weather, and fatigue — CULTURE

Malcomb  Gladwell makes an interesting point as it relates to Korean culture . . . .

The Korean linguist Ho-min Sohn writes . . . . All social behavior and actions are conducted in the order of seniority or ranking; as the saying goes. . . . there is order even to drinking cold water.”

So, when the first officer says, “Don’t you think it rains more?  In this are, here?”  we know what he means by that:  Captain.   You have committed us to a visual approach, with no backup plan, and the weather outside is terrible.  You think that we will break out of the clouds in time to see the runway.  But what if we don’t?  It’s pitch-black outside and during rain and the glide slope is down.

But he can’t say that.  He hints, and in his mind, he’s said as much as he can to a superior.  The first officer will not mention the weather again.”

Key Illustrative Thoughts:

Should I say anything?
Confusion cost lives.
Who knew?
Life & Death — It’s time to speak up.
Wrong assumptions
High errant conditions
Intermittent erroneous signals cause crashes.
It may not be a reliable guidance system.
Out for repair
It’s not in sight — but there is no going around.
Sometimes you can and sometimes you can’t.
Some airports require a special qualification because they are more dangerous.
Try it when it is clearly far safer, before you find yourself under high errant conditions.
There are no conditions when it is safer.
Regardless of its apparent validity
He is really saying . . . . But you can’t hear it!
The Glide Slope is down.
Experience is no assurance.
Even well-experienced people have been known to crash.
Can people talk to you?
Title: Ways to shut down helpful conversations — Subtitle: Ways to set up a crash.


Additional Information & Links

Pilot Confusion: At one point the captain stated that the glideslope was not working, then he said that it was working, and then again stated that it was not working.

* The crew was operating on an old flight map which stated that the safe altitude for landing a plane was 1,700 feet.  The updated flight map, which was revised to 2,150.  Flight 801 was maintaining an altitude of 1,870 while it was waiting to land.

VOR:  VOR stands for “VHF   Omnidirectional   Range.”    The tower sends out a VHF signal which transmits  — The station’s identifier and the magnetic bearing from the station to the airplane.  That bearing is used by the pilot to determine the plane’s exact position and allows them to navigate to the runway.

DME: Distance Measuring Equipment

Animated presentation of the crash:



Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.