# NTSB ATL91LA122: Learjet 23, N500FM, Columbia, TN, July 2, 1991

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: July 2, 1991, 18:56 local (23:56 UTC)
- Place: Columbia, TN
- Coordinates: 35.619609, -87.039344 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=35.6196&lon=-87.0393&mi=10
- Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 2 uninjured
- Status: Completed, report July 13, 1993
- Report: Approved by Office Director
- NTSB case key (mKey): 8427
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ATL91LA122
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/8427/pdf
- Page: https://openairdocs.org/ntsb/ATL91LA122

## Probable cause

THE PILOT'S PREMATURE DECISION TO TURN OFF THE ANTI-SKID DURING LANDING ROLL.  FACTORS TO THIS ACCIDENT WERE HYDROPLANING CONDITIONS.

## Sequence of events

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

- On ground/water encounter with terrain/water, landing - roll
  - terrain condition - ground
  - landing gear,anti-skid brake system
  - procedures/directives - discontinued, pilot in command (cause)
  - planning/decision - premature, pilot in command (cause)
  - aircraft performance,hydroplaning condition (contributing factor)

## Analysis

THE PILOT HAD COMPUTED LANDING PERFORMANCE INFORMATION FOR A LANDING ON A WET RUNWAY WITH ANTI-SKID; SUFFICIENT RUNWAY SURFACE WAS AVAILABLE. TOUCHDOWN WAS NORMAL, HOWEVER DURING THE BRAKING PROCESS, THE AIRPLANE STARTED TO FISHTAIL AND THE PILOT BELIEVED THAT THE ANTI-SKID SYSTEM HAD FAILED.  THEREFORE, THE PILOT TURNED THE ANTI-SKID SYSTEM OFF AND CONTINUED THE ROLLOUT WITH NORMAL BRAKING.  THE AIRPLANE WENT OFF THE DEPARTURE END OF RUNWAY 05 AND SUSTAINED SUBSTANTIAL DAMAGE.  PERFORMANCE DATA INDICATED MORE RUNWAY SURFACE WAS REQUIRED FOR A SAFE LANDING ON A WET RUNWAY WITHOUT ANTI-SKID ASSISTANCE.  THE BRAKING SEQUENCE OF EVENTS DESCRIBED BY THE PILOT RESEMBLED DYNAMIC HYDROPLANING WHERE THERE WAS A COMPLETE LOSS OF BRAKING EFFECTIVENESS RATHER THAN AN ANTI-SKID MALFUNCTION.  AN EXAMINATION OF THE AIRPLANE FAILED TO DISCLOSE ANY MECHANICAL PROBLEMS.

## Aircraft

- Registration: [N500FM](https://openairdocs.org/deregistered/N500FM-1999-06-14), registration cancelled 1999-06-14, S/N 088 (OpenAirDocs)
- Reported make and model: LEARJET 23
- Registry model: [Learjet 23](https://openairdocs.org/model/learjet-23) (registry code 5170102) (OpenAirDocs)
- Category: Airplane
- Serial number: 23-088
- Airframe hours: 13594
- Engines: GE CJ610-4 2850 lbs thrust turbo jet
- Damage: Substantial damage
- Flight: Part 135
- Operator: Connie Kalitta Services, Inc.
- Registered owner: Connie Kalitta Services, Inc.
- Airworthiness certificate: Standard, Normal
- Last inspection: AAIP, June 10, 1991, 43 hours before
- Departed: YNG, YOUNGTOWN, OH
- Flight plan: IFR
- Airport: Maury County, runway 5, 5,009 × 75 ft, asphalt

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 28; airline transport, flight instructor; airplane ratings: multi-engine land; instrument ratings: airplane; medical: class 1, valid medical--w/ waivers/lim; seat: left; flight hours: 4,964 total, 4,039 in this make and model, 4,039 as pilot in command, 285 in the last 90 days, 77 in the last 30 days, 2 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 290° at 4 knots
- Visibility: 10 statute miles
- Lowest ceiling: none
- Altimeter: 29.00 inHg
- Observed at: MRC, 1 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 19910702026029A](https://openairdocs.org/incident/19910702026029A), Jul 2, 1991: Lear 23LEAR, Columbia/Mt Ple, TN, Substantial damage. Overran wet runway on landing roll. No mechanical. Hydroplaning possible.

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.

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