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Accident description
Last updated: 13 December 2017
Status:Final
Date:Monday 31 March 1975
Time:07:43
Type:Silhouette image of generic B732 model; specific model in this crash may look slightly different
Boeing 737-247
Operator:Western Air Lines
Registration: N4527W
C/n / msn: 20131/165
First flight: 1969-05-07 (5 years 11 months)
Total airframe hrs:14076
Engines: 2 Pratt & Whitney JT8D-9A
Crew:Fatalities: 0 / Occupants: 6
Passengers:Fatalities: 0 / Occupants: 93
Total:Fatalities: 0 / Occupants: 99
Airplane damage: Damaged beyond repair
Location:Casper Airport, WY (CPR) (   United States of America)
Phase: Landing (LDG)
Nature:Domestic Scheduled Passenger
Departure airport:Denver-Stapleton International Airport, CO (DEN/KDEN), United States of America
Destination airport:Casper Airport, WY (CPR/KCPR), United States of America
Flightnumber: 470
Narrative:
Western Air Lines flight 470 to Casper and Minneapolis departed Denver at 07:03 in the morning. The airplane, on an IFR flightplan, climbed to its cruising altitude of FL220. At 07:36, following a descent to 12,000 feet, the flightcrew contacted Casper approach control and advised that the flight was about 12 miles south of the Evansville Intersection. At that time, the controller cleared the flight to use the localizer back course approach for runway 25, to circle to runway 3, or to land straight in. The weather reported to the crew indicated poor visibility with light snow falling and wind 040deg at 9 knots. One minute later, the approach controller advised that "runway 7/25 has been
plowed. There's about a 1/4-inch of powder snow on it. Braking action reported, Convair 580, as poor. Runway 3/21 is being plowed at this time."
At 07:51, Flight 470 reported at the Henning Intersection and was cleared to contact the Casper Tower. The tower controller cleared the flight to land on runway 25 and gave the wind as 030deg at 8 knots. The flight was also advised by the controller that a disabled snow blower was "just west of the intersection runway 21, left side runway 25, on the edge ...." At 07:41:42, the first officer called out "thousand to go to the field." At 07:42:09, the first officer called "approaching minimums," and 12 seconds later, he called "just about at minimums."
The aircraft then flew level for a few moments a t the minimum descent altitude (MDA). At 07:42:25,
the first officer called the runway in sight directly below the aircraft. At that time airspeed was 150 knots and the flaps were at 25deg. The first office then set the flaps at 30deg as the captain initiated the final descent. The aircraft crossed the threshold at reference speed +15 knots. The aircraft touched down 2375 feet from the departure end of the runway, about 6,306 feet from the approach end of the runway. The aircraft went off the departure end of the runway to the right of the centerline. After striking several metal stanchions in the first row of terminal bar lights, which were located 200 feet off the end of the runway, the aircraft struck a shallow irrigation ditch 280 feet off the runway end. The aircraft veered farther to the right and stopped about 800 feet beyond the departure end of the runway.

Probable Cause:

PROBABLE CAUSE: "The failure of the pilot-in-command to exercise good judgment when he failed to execute a missed approach and continued a non-precision approach to a landing without adequately assessing the aircraft's position relative to the runway threshold. Contributing tot the accident were the excessive height and speed at which he crossed the approach end of the runway and the failure of other flight crew members to provide him with required callouts."

Accident investigation:
cover
Investigating agency: NTSB
Status: Investigation completed
Duration: 213 days (7 months)
Accident number: NTSB/AAR-75-15
Download report: Final report

Classification:
Runway excursion

Sources:
» ICAO Circular 146-AN/96 (60-76)


Follow-up / safety actions

NTSB issued 1 Safety Recommendation

Show all AD's and Safety Recommendations

Photos

photo of Boeing 737-247 N4527W
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Map
This map shows the airport of departure and the intended destination of the flight. The line between the airports does not display the exact flight path.
Distance from Denver-Stapleton International Airport, CO to Casper Airport, WY as the crow flies is 370 km (231 miles).

This information is not presented as the Flight Safety Foundation or the Aviation Safety Network’s opinion as to the cause of the accident. It is preliminary and is based on the facts as they are known at this time.
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