# NTSB DEN87IA145: Boeing 727-251, N297US, Casper, WY, June 2, 1987 - Type: NTSB incident investigation - Classification: Incident · No injuries · Incident investigation · Final report - Date: June 2, 1987, 10:12 local (16:12 UTC) - Place: Casper, WY - Location: 42.8421° N, 106.3213° W: Placed by OpenAirDocs: center of Casper, WY, within about 6 miles (OpenAirDocs) - Nearby events: https://openairdocs.org/map.md?lat=42.8421&lon=-106.3213&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 72 uninjured - Status: Completed, report October 17, 1988 - Report: Approved by Office Director - NTSB case key (mKey): 17138 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DEN87IA145 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/17138/pdf - Page: https://openairdocs.org/ntsb/DEN87IA145 ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Near collision between aircraft, cruise - normal - radar,en route - failure,partial (contributing factor) - artcc service - excessive workload (task overload), atc personnel(artcc) (contributing factor) - improper decision, faa(other/organization) (contributing factor) - radio communications - not understood, atc personnel(artcc) (cause) - atc clearance - inaccurate, atc personnel(artcc) (cause) - communications/information/atc - not understood, pilot of other aircraft - radar,conflict alert - inoperative (contributing factor) - ifr separation standards - not maintained (cause) - Near collision between aircraft, cruise - normal - radar,en route - failure,partial (contributing factor) - artcc service - excessive workload (task overload), atc personnel(artcc) (contributing factor) - improper decision, faa(other/organization) (contributing factor) - radio communications - not understood, atc personnel(artcc) (cause) - atc clearance - inaccurate, atc personnel(artcc) (cause) - communications/information/atc - not understood, pilot in command - radar,conflict alert - inoperative (contributing factor) - ifr separation standards - not maintained (cause) ## Analysis (aircraft 2) BOEING 727 (NORTHWEST FLT 354) & USAF EC-135 (SLUM 51) WERE INVOLVED IN A NR COLLISION AT FL 330. THE MISHAP OCCURRED ASFLT 354 WAS ENE BND ON J-158 & SLUM 51 WAS FLYING ON A RADIAL-DISTANCE (R/D) FLT PLN, FLYING BTN R/D PTS SOUTH OF J-158.AS SLUM 51 APCHD ITS MOST WESTERN PT, THE CREW REQD A RGT TURN TO A R/D PT THAT WAS NOT THE NEXT LISTED PT ON THEIR FLT PLN. THE TRAINEE CTLR (T/C) DIDN'T REALIZE SLUM 51 WAS REQG A ROUTE CHG, BUT THOUGHT THE FLT WANTED TO TURN BACK EAST TOTHE NEXT FILED R/D PT WITH A RGT TURN (INSTEAD OF A L TURN AS PREVIOUSLY DONE). THE T/C REPLIED, 'UNABLE RGT TURN, MAKE A LEFT TURN.' THE INSTRUCTOR HEARD THE REQ, BUT THOUGHT THE T/C'S REPLY WAS DISAPPROVAL OF A ROUTE CHG. AS THE CTLRS TURNED THEIR ATTN TO OTR (HVY/COMPLEX) TRAFFIC, SLUM 51 CONTD A 270 DEG L TURN (TO NORTH) & CONVERGED WITH FLT 354. THE 9020 (PRIMARY) COMPUTER WAS INOP; THE DARC (BACKUP) COMPUTER HAD NO CAPABILITY OF DISPLAYING PROJECTED ROUTES OR PROVID-ING CONFLICT ALERT. NO FLOW CTL RESTRICTIONS WERE IN EFFECT TO RDC THE AMOUNT OF TRAFFIC. ## Aircraft 1 - Registration: [N297US](https://openairdocs.org/deregistered/N297US-2004-05-27), registration cancelled 2004-05-27, S/N 21789, built 1979 (OpenAirDocs) - Reported make and model: BOEING 727-251 - Registry model: [Boeing 727-251](https://openairdocs.org/model/boeing-727-251) (registry code 138408H) (OpenAirDocs) - Registry engine: [Pratt & Whitney JT8D-9 series](https://openairdocs.org/engine/pratt-whitney-jt8d-9-series) (registry code 52048, turbo-jet) (OpenAirDocs) - Category: Airplane - Serial number: 21789 - Engines: P&W JT8D 14500 lbs thrust turbo fan - Damage: No damage - Flight: Part 121 - Registered owner: Northwest Airlines, Inc. - Airworthiness certificate: Standard, Transport - Departed: SFO, SAN FRANCISCO, CA - Destination: MSP, MINNEAPOLIS, MN - Flight plan: IFR ## Aircraft 2 - Registration: USAF (not matched to a registry record) - Reported make and model: Boeing EC-135 - Category: Airplane - Engines: P&W J-57 13750 lbs thrust turbo jet - Damage: No damage - Flight: Armed forces - Registered owner: United States Air Force - Departed: RCA, RAPID CITY, SD - Flight plan: IFR ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot, aircraft N297US; age 44; airline transport; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 1, valid medical--no waivers/lim.; seat: left; flight hours: 12,230 total, 10,000 in this make and model - Pilot, aircraft 2; age 39; commercial, military; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: unknown, valid medical--no waivers/lim.; seat: left; flight hours: 6,000 total, 3,300 in this make and model ## Weather - Conditions: Visual (VMC), Day - Lowest ceiling: none ## FAA reports on this event (1) The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs). - [Incident 19870602080319I](https://openairdocs.org/incident/19870602080319I), Jun 2, 1987: Boeing 727247, Casper, WY. Trainee radar controller allowed two aircraft to have less than standard separation. Primary computer was down. From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.