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Northwest Airlines Butte Archives Talk
1. Northwest Airlines Flight 115
Butte, Montana
November 7, 1950
Kristi Dunks
Butte Archives Brown Bag Lunch Series
November 27, 2013
2. Accident Investigation History
• Air Commerce Act of 1926
• 1940- Civil Aeronautics Board’s Bureau of Aviation
Safety
• 1967- National Transportation Safety Board (NTSB)
established within Department of Transportation
• 1974- Congress reestablishes NTSB as an
independent agency
4. Mrs. Fannie Katharine Backa
Marcia Jo Backa
Karen Kay Backa
Margaret Fairwweather
Mrs. Bernice Hazel Gray
James Andrew Huff
George Lewis Killorn
Lloyd George Lampman
Walter N. Lundby
Lucille Ida Lundby
Mary Menzel
Lilas A. Morris
Lauraine Johanna Nohr
Charles L. Miller
Louis Phillips
Harold J. Rhein
Robert Clarence Shull
Arthur N. Sogaard
Gerard J. Verhelst
Vincent James Walsh
Louis Wien
Marjorie Elizabeth White
5.
6.
7. Route of Flight
• Departed Helena runway 29 at 0753
• Flight plan specified an altitude of 10,500 feet under
instrument flight rules
• Via Amber Airway No. 2 to the Whitehall (Montana)
Range Station
• Via Red Airway No. 2 to the Butte Airport
8. Route of Flight
• 0814 flight reported over “Whitehall [range station]
at 0811 and starting decent”
• Butte Radio provided the altimeter setting, advised
that the wind was south, calm, and that the ceiling
was lower to the east and north and better to the
south and southwest
• Flight 115 reported a vertical visibility at 10,500 feet
• No further communication from the flight
9. Search and Rescue
• Wreckage spotted at 0900 AM on November 8 by a
search aircraft
• Ground parties started for site
• Numerous families living in the Homestake area
provided food and assistance to rescuers
10. Search and Rescue
“Determination of the searching groups to reach the
fallen airline Tuesday, in hope that if anyone aboard
were alive he might be rescued, is exemplified in the
number of men that remained in the mountain
wilderness Tuesday night, several of whom battled
their way through gullies, over fallen timber and up
and around huge mountain boulders until after
midnight.”
– The Montana Standard, Nov 9, 1950
14. Recovery
“A thin line of struggling, stumbling men scaled the
Butte side of the jagged Continental Divide
Wednesday afternoon and night to bring down the
sacked bodies of the 22 persons whose lives were lost
some 36 hours earlier in the smashup of a Northwest
Airlines plane.”
– The Montana Standard, Nov 9, 1950
16. Official Investigation
• Aircraft struck eastern slope of ridge about 30 feet
below its crest, at an elevation of 8,250 feet msl
• Heading 290 degrees magnetic
• 2.5 miles east of the Butte Airport
• 1.5 miles right of the center of the on-course signal
from Whitehall to Butte
• Ridge struck “paralleled by another somewhat
similar ridge approximately three or four miles to the
east”
17. Documentation of
Wreckage
• The aircraft struck while about level longitudinally
• The left wing impacted trees first, followed by the
nose section and left wing “striking rimrock solidly”
• The control systems and engines were extensively
damaged but showed no operational anomalies
• The instrumentation was “severely damaged and
burned” so investigators were unable to determine
what frequencies had been set
• Automatic direction finding (ADF) receivers showed
one tuned to the Butte Range and the other to the
Whitehall Range
18. Witness 1
• Mr. Roffler, a rancher living about 10 miles eastsoutheast of the accident site, was in his house
located about 2.5 miles north of the Whitehall
Range Station
• “While returning from milking his cows between 0805
and 0810” he saw the airplane about ½-mile north
and it continued on a straight course
• He noted that a snowstorm obscured the
mountains, but the weather was otherwise good
• This aircraft appeared lower than other aircraft he
had seen pass over his property
19. Witness 2
• Mrs. Setzer was “outside her home in the mountains”
about 2 miles east of the crash site and 2 miles north
of the Homestake Fan Marker
• She came into the house to listen to the 0800 news,
but she noted it was 0810 and went back out to
finish her work
• She heard the airplane come from the east, pass
north of her home, continue to the west, and then
she heard the accident
• Falling snow and low clouds prevented her from
seeing the airplane
20. Weather
• Overcast forecast for the route with bases ranging
from 6,000 to 10,000 feet, and tops at 14,000 feet
• Visibility 2-6 miles in snow showers
• Butte terminal forecast indicated 4,000-foot ceiling
with snow showers
• Aftercast indicated from Helena the airplane was in
the clouds with snow showers, with periods of
vertical visibility
• Over Whitehall, ceiling was 4,000 feet, visibility 30
miles, wind west-southwest 10, and storming in
mountains in all quadrants
• Moderate turbulence near accident site
23. Instrument Procedure
• Pass over Whitehall Range Station, proceed out on
a west leg on course of 275 magnetic, while on this
leg, pass over and receive a signal (visual and
aural) from the Homestake Fan Marker
• Fan marker shall be crossed at an altitude of 9,500
feet, and then a descent can start to 8,050 feet on
a 275 degree course from the Butte Airport
25. Matter of “Multiples”
• Used to describe the existence of an additional
course or courses lying to one or both sides of the
center line of the published course, generally over
mountainous terrain
• Such “multiples” existed on the west leg of the
Whitehall Range and their existence had “been
long known”
• Occur “only to the west of the Homestake Fan
Marker”
26. Matter of “Multiples”
• If prescribed approach procedures followed, the
multiples on the west leg of the range were not
hazardous to flight, “by virtue of their weakness,
geographical location, and relatively small
displacement from the true on-course signal.”
WARNING: Low frequency range courses are subject to
disturbances that result in multiple courses and signal fades
or surges over rough country. Pilots flying over unfamiliar
routes are cautioned to be alert to detect these vagaries,
particularly over mountainous terrain.
- CAA Flight Information Manual
27. Accident Scenario
• Flight turned toward about Butte 3 miles short
(before passing over Whitehall Range Station)
• Weather indicated periods of visibility so it is possible
that visually passing through Homestake Pass was
anticipated
• Flight path could have resulted in aural indication
from Homestake Fan Marker
• Terrain paralleling accident site ridge may have
been mistaken for the ridge that was struck while
flying “on and off” instruments
28. Safety Changes
• Required higher ceiling and visibility minimums for
Northwest Airlines operations on both domestic and
international routes
• Establishment of concentrated pilot training program
• Required comprehensive inspection of all company
aircraft
• Restricted operations to 225 miles for 4-engine aircraft,
and 150 for 2-engine aircraft unless an airport having the
higher weather was available within such distances
• Restricted flight schedules to allow sufficient time to
accomplish maintenance
35. Additional Information
• Visit the Butte Archives
o CAB report
o Newspaper articles
o Photographs of site
• CAB Reports (1934-1965)
o www.dotlibrary.specialcollection.net/
• NTSB Reports
o www.ntsb.gov
• Wreck Finding
o www.aircraftwrecks.com/
