# NTSB DEN92FA020: Grumman American AA-5A, N9991U, Monte Vista, CO, December 25, 1991

- Type: NTSB accident investigation
- Classification: Accident · Fatal · Field investigation · Final report
- Date: December 25, 1991, 14:30 local (21:30 UTC)
- Place: Monte Vista, CO
- Coordinates: 37.56998, -106.13932 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=37.5700&lon=-106.1393&mi=10
- Phase of flight: [Initial climb](https://openairdocs.org/ntsb-phases/350) (OpenAirDocs' grouping)
- Highest injury: Fatal
- Injuries: 3 fatal
- Status: Completed, report April 23, 1993
- Report: Approved by Office Director
- NTSB case key (mKey): 18143
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DEN92FA020
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/18143/pdf
- Page: https://openairdocs.org/ntsb/DEN92FA020

## Probable cause

AN INADVERTENT STALL BY THE PILOT IN COMMAND AT AN ALTITUDE INSUFFICIENT TO EFFECT RECOVERY.  FACTORS WERE:  AIRCRAFT GROSS WEIGHT ABOVE MAXIMUM; PHYSICAL IMPAIRMENT OF THE PILOT; LACK OF TOTAL EXPERIENCE; LACK OF RECENT EXPERIENCE; AND LACK OF EXPERIENCE IN TYPE.

## Sequence of events

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

- Loss of control - in flight, takeoff - initial climb
  - stall - inadvertent, pilot in command (cause)
  - physical impairment(carbon monoxide), pilot in command (contributing factor)
  - aircraft weight and balance - exceeded, pilot in command (contributing factor)
  - lack of total experience, pilot in command (contributing factor)
  - lack of total experience in type of aircraft, pilot in command (contributing factor)
  - lack of recent experience in kind of aircraft, pilot in command (contributing factor)
- In flight collision with terrain/water, descent - uncontrolled
  - terrain condition - open field
  - terrain condition - frozen

## Analysis

WHILE ON A POST TAKEOFF CROSSWIND CLIMB, THE PILOT INADVERTENTLY STALLED THE AIRCRAFT AT A LOW ALTITUDE.  THE AIRCRAFT IMPACTED VERTICALLY IN A FROZEN OPEN FIELD.  INVESTIGATION REVEALED THE AIRCRAFT TO BE 90 POUNDS OVER MAXIMUM GROSS WEIGHT; THE PILOT TO BE SUFFERING FROM PHYSICAL IMPAIRMENT DUE TO CARBON MONOXIDE POISONING; THE PILOT TO BE LOW IN TOTAL EXPERIENCE, EXPERIENCE IN TYPE; AND RECENT EXPERIENCE.  TOXICOLOGY TESTS REVEALED 16% CARBOXYHEMOGLOBIN IN THE PILOT'S BLOOD.  PASSENGER TEST RESULTS WERE NEGATIVE.  THAT SATURATION LEVEL CAN CAUSE DEGRADATION IN JUDGMENT AND PERFORMANCE.  THE PILOT WAS A MECHANIC AND HAD BEEN EXPOSED TO RUNNING ENGINES IN A NON-VENTILATED SHOP THE DAY/EVENING PRIOR TO THE ACCIDENT.

## Aircraft

- Registration: [N9991U](https://openairdocs.org/deregistered/N9991U-1992-04-21), registration cancelled 1992-04-21, S/N AA5A0391 (OpenAirDocs)
- Reported make and model: GRUMMAN AMERICAN AA-5A
- Registry model: [Grumman American Avn. AA-5A](https://openairdocs.org/model/grumman-american-avn-aa-5a) (registry code 3960106) (OpenAirDocs)
- Category: Airplane
- Serial number: AA5A0391
- Airframe hours: 3702
- Engines: LYCOMING O-320-E2G 150 horsepower reciprocating
- Damage: Destroyed
- Flight: Personal, Part 91
- Operator: Fred Schrotenboer, doing business as San Luis Valley Aviation
- Registered owner: Fred Schrotenboer
- Airworthiness certificate: Standard, Normal
- Last inspection: 100 hour, November 7, 1991, 39 hours before

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 37; private; airplane ratings: single-engine land; medical: class 3, valid medical--no waivers/lim.; seat: left; toxicology performed; flight hours: 83 total, 2 in this make and model, 49 as pilot in command, 2 in the last 90 days

## Weather

- Conditions: Visual (VMC), Day
- Wind: 190° at 5 knots
- Visibility: 60 statute miles
- Lowest ceiling: none
- Temperature: 10 °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 19911225057239A](https://openairdocs.org/incident/19911225057239A), Dec 25, 1991: Gulstm AA5A, Monte Vista, CO, Destroyed, 3 fatal. Indicates stall on climbout. Over gross weight. Pilot high level carbon monoxide. Possibly from work as auto mechanic

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.