# NTSB MKC86MA031: Rockwell 500-S, N81589, Des Moines, IA, November 25, 1985

- Type: NTSB accident investigation
- Classification: Accident · Fatal · Major investigation · Final report
- Date: November 25, 1985, 17:42 local (23:42 UTC)
- Place: Des Moines, IA
- Coordinates: 41.529506, -93.659317 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=41.5295&lon=-93.6593&mi=10
- Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping)
- Highest injury: Fatal
- Injuries: 7 fatal
- Status: Completed
- Report: Approved by Office Director
- NTSB case key (mKey): 34257
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=MKC86MA031
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/34257/pdf
- Page: https://openairdocs.org/ntsb/MKC86MA031

## Sequence of events

In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf).

- Loss of control - in flight, approach - faf/outer marker to threshold (ifr)
  - light condition - dark night (contributing factor)
  - weather condition - low ceiling (contributing factor)
  - weather condition - fog (contributing factor)
  - weather condition - rain (contributing factor)
  - weather condition - icing conditions (contributing factor)
  - wing - ice (cause)
- Altitude deviation,uncontrolled, approach - faf/outer marker to threshold (ifr)
  - airspeed - reduced, pilot in command (contributing factor)
  - airspeed - inadequate, pilot in command (cause)
  - aircraft handling - not maintained, pilot in command (cause)
  - descent - uncontrolled
  - directional control - not maintained
  - remedial action - initiated
  - level off - performed
- Loss of engine power, approach
  - reason for occurrence undetermined (contributing factor)
- In flight collision with object, approach
  - terrain condition - rising (contributing factor)
  - proper climb rate - not possible
  - stall/mush
  - object - tree(s) (contributing factor)
  - object - wire,transmission (contributing factor)
  - object - utility pole (contributing factor)
- In flight collision with terrain/water, descent - uncontrolled

## Analysis

N81589 WAS FLWG A BOEING 727 ON ILS APCH IN IFR CONDS. APRX 2.5 MI FM RWY, N81589 SUDDENLY DEVIATED LEFT NRLY 90 DEG. 39 SEC LATER, PLT RPRTD HE ENCTRD SVR TURBC, THEN SAID HE WAS TRYING TO CLB. N81589 SUBSEQUENTLY FLEW THRU TREE TOPS ON RISING TRRN FOR APRX 2 CITY BLKS, THEN HIT PWR LNS & A POLE & CRASHED AGAINST A TREE. NO EVIDENCE OF TURBC DUE TO WX AT/NR APCH ALT. INV SHOWED 4.7 MI SEPN BTN ACFT WHEN THE 727 PASSED THE POINT OF DVN (POD). AT POD, THE 727 WAS ON THE ILS GLIDE SLOPE AT 850'; N81589'S ALT WAS NOT DETERMINED. WND WAS FM 120 DEG AT 3 TO 6 KTS, SHIFTING MORE SOUTHERLY WITHALT. PREVAILING VIS WAS 1/2 MI; RVR FOR RWY 12L WAS 6000'; LGT RIME ICG WAS RPRTD. WITNESSES HEARD PWR INTERUPTION OF 1 ENG AT POD; BUT THERE WAS NO INDCN OF PWR LOSS WHERE ACFT HIT TREES. RADAR DATA SHOWED ACFT SLOWED TO 80 KTS AT POD, ACCELERATED TO 100 KTS DRG DVN, SLOWED TO 70 KTS BFR IMPACT; VMCA WAS 74 KTS. SAFETY BOARD BELIEVES THE PLT MOST LIKELY LOST CONTROL DUE TO SLOW SPD & LGT AIRFRAME ICG; POSSIBLY ENCTRD WAKE TURBC. NO REASON FND FOR LOSS OF ENG PWR.

## Aircraft

- Registration: N81589 (not matched to a registry record)
- Reported make and model: Rockwell 500-S
- Category: Airplane
- Serial number: 3297
- Airframe hours: 3185
- Engines: LYCOMING IO-540-E1B5 290 horsepower reciprocating
- Damage: Destroyed
- Fire: On-Ground
- Flight: Public aircraft, Part 91
- Operator: Iowa State University
- Airworthiness certificate: Standard, Normal
- Last inspection: Annual, October 4, 1985, 41 hours before
- Departed: MKE, MILWAUKEE, WI
- Flight plan: IFR
- Airport: DSM, Des Moines Muni, runway 12L, 9,000 × 150 ft, asphalt

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 59; commercial, flight instructor; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 2, valid medical--w/ waivers/lim; seat: left; toxicology performed; flight hours: 7,020 total, 1,553 in this make and model, 6,838 as pilot in command, 72 in the last 90 days, 2 in the last 24 hours

## Weather

- Conditions: Instrument (IMC), Night/dark
- Wind: 120° at 5 knots
- Lowest ceiling: 100 ft overcast
- Temperature: 30 °F, dew point 28 °F
- Altimeter: 29.00 inHg
- Observed at: DSM, 2 nm away

## FAA reports on this event (1)

The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs).

- [Accident 19851125058059A](https://openairdocs.org/incident/19851125058059A), Nov 25, 1985: Gulstm 500S, Des Moines, IA, Destroyed, 7 fatal. On ILS deviated 90 degrees off LOC. Flew thru tree tops in city. Hit wires and tree. Wake turbulence behind plane.

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.