# NTSB DEN91LA106: Cessna 210B, N9711X, Aspen, CO, August 1, 1991

- Type: NTSB accident investigation
- Classification: Accident · Serious injuries · Limited investigation · Final report
- Date: August 1, 1991, 13:55 local (19:55 UTC)
- Place: Aspen, CO
- Coordinates: 39.189914, -106.819625 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=39.1899&lon=-106.8196&mi=10
- Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping)
- Highest injury: Serious injuries
- Injuries: 2 serious, 1 minor
- Status: Completed, report March 10, 1993
- Report: Approved by Office Director
- NTSB case key (mKey): 18118
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DEN91LA106
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/18118/pdf
- Page: https://openairdocs.org/ntsb/DEN91LA106

## Probable cause

A PILOT INDUCED INADVERTENT STALL.  FACTORS WERE:  THE PILOT'S FAILURE TO ASCERTAIN THE LANDING GEAR WAS DOWN AND LOCKED IN A TIMELY MANNER, A LOW (FLUID) LEVEL IN HYDRAULIC RESERVOIR, CAUSING THE HYDRAULIC PUMP TO FLUCTUATE (CAVITATE), AND THE PILOT'S ATTENTION BEING DIVERTED.

## Sequence of events

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

- Loss of control - in flight, go-around (vfr)
  - gear down and locked - not attained (contributing factor)
  - hydraulic system,reservoir - low level (contributing factor)
  - hydraulic system,pump - fluctuating (contributing factor)
  - go-around - initiated, pilot in command
  - diverted attention, pilot in command (contributing factor)
  - aircraft performance,climb capability - exceeded
  - stall - inadvertent, pilot in command (cause)
- In flight collision with object, descent - uncontrolled
  - object - tree(s)

## Analysis

THE PILOT DID NOT GET A LANDING GEAR DOWN AND LOCKED INDICATION AFTER BEING CLEARED TO LAND.  DURING THE GO AROUND, THE PILOT ATTEMPTED TO TURN TO AVOID BUILDINGS AND THE AIRPLANE STALLED AND CRASHED INVERTED INTO A TREE.  THERE WAS NO EVIDENCE OF HYDRAULIC FLUID LEAKAGE.  FUNCTIONAL TESTING OF

## Aircraft

- Registration: [N9711X](https://openairdocs.org/deregistered/N9711X-1992-01-30), registration cancelled 1992-01-30, S/N 21058011 (OpenAirDocs)
- Reported make and model: CESSNA 210B
- Registry model: [Cessna 210B](https://openairdocs.org/model/cessna-210b) (registry code 2073410) (OpenAirDocs)
- Category: Airplane
- Serial number: 21058011
- Engines: CONTINENTAL IO-470S-1B 260 horsepower reciprocating
- Damage: Destroyed
- Flight: Personal, Part 91
- Operator: Muller, Francis J.
- Registered owner: Muller, Francis J.
- Departed: MLF, MILFORD, UT
- Airport: ASE, Aspen-Pitkin C. Sardy Fie, runway 15, 7,003 × 100 ft, asphalt

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 50; private; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 3, valid medical--w/ waivers/lim; flight hours: 602 total, 165 in this make and model, 15 in the last 90 days, 6 in the last 30 days, 6 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 350° at 8 knots
- Visibility: 20 statute miles
- Lowest ceiling: 6,000 ft broken
- Temperature: -0 °F, dew point -0 °F

## 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 19910801031149A](https://openairdocs.org/incident/19910801031149A), Aug 1, 1991: Cessna 210B, Aspen, CO, Destroyed. Unsafe gear on approach. Began belated go around. Unable climb. Stalled. Hydraulic reservoir empty. No leaks noted.

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.