# NTSB CHI91MA224: Learjet 23, N959SC, Detroit, MI, July 23, 1991

- Type: NTSB accident investigation
- Classification: Accident · Fatal · Major investigation · Final report
- Date: July 22, 1991, 21:15 local (Jul 23, 1991, 01:15 UTC)
- Place: Detroit, MI
- Coordinates: 42.399517, -83.000015 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=42.3995&lon=-83.0000&mi=10
- Phase of flight: [Takeoff](https://openairdocs.org/ntsb-phases/300) (OpenAirDocs' grouping)
- Highest injury: Fatal
- Injuries: 3 fatal
- Status: Completed, report September 11, 1992
- Report: Approved by Office Director
- NTSB case key (mKey): 15196
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CHI91MA224
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/15196/pdf
- Page: https://openairdocs.org/ntsb/CHI91MA224

## Probable cause

IMPROPER PREFLIGHT BY THE PILOT, HIS FAILURE TO ABORT THE TAKEOFF WHILE THERE WAS SUFFICIENT RUNWAY REMAINING, AND HIS FAILURE TO ASSURE THAT THE AIRCRAFT ATTAINED SUFFICIENT AIRSPEED FOR LIFT-OFF AND CLIMB.  FACTORS RELATED TO THE ACCIDENT WERE:  THE PILOT'S FAILURE TO ASSURE THE AIRCRAFT WAS WITHIN ITS MAXIMUM WEIGHT LIMITATION, HIS IMPROPER USE OF THE PARKING BRAKE, AND INSUFFICIENT INFORMATION IN THE PILOT OPERATING HANDBOOK CONCERNING THE AIRCRAFT PARKING BRAKE.

## Sequence of events

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

- Loss of control - in flight, takeoff
  - aircraft preflight - inadequate, pilot in command (cause)
  - aircraft weight and balance - improper, pilot in command (contributing factor)
  - aircraft manuals,system information - inadequate (contributing factor)
  - parking brakes - improper use of, pilot in command (contributing factor)
  - information insufficient, manufacturer (contributing factor)
  - aborted takeoff - not performed, pilot in command (cause)
  - lift-off - premature, pilot in command (cause)
  - stall/mush
- In flight collision with object, takeoff
  - object - tree(s) (contributing factor)
- In flight collision with terrain/water, descent - uncontrolled

## Analysis

A LINEMAN NOTED PARKING BRAKE (P/B) WAS SET BFR FLT. PLTS BGN TKOF ON 5147' RWY WITH 10 KT X-WND. A WITNESS SAID ACFT ROTATED FOR TKOF ABT 4500' DWN RWY & LIFTED OFF ABT 50' LTR. RPRTDLY, IT RMND LOW & SLOW (20-60 FT AGL) AFTER LIFT-OFF, THEN BANKED (ROCKED) LEFT & RIGHT IN NOSE HI ATTITUDE, SETTLED, HIT TREES & CRASHED ABT 200' BYD RWY. ONE PERSON SAID ACFT WENT OUT OF CTL BFR IMPACT; ANOTHER SAID IT WAS 'IN OR ON THE EDGE OF STALLED FLIGHT.'  EXAM SHOWED ROTATIONAL DMG OCCURRED IN BOTH ENGS DRG IMPACT. THE BRAKING SYS HAD EVIDENCE THAT P/B CTL VLV WAS PARTIALLY ON; BRAKE TORQUE TUBE CONTAINED HEAT BLUEING. ON THIS EARLY MODEL (LEARJET 23/SN: 23-45A), P/B HAD TO BE RLSD BY DEPRESSING BRAKE PEDALS 1ST; PLT HANDBOOK DID NOT ADDRESS THIS. ON LTR MODELS (SN: 23-050 & UP), P/B NEEDED ONLY TO BE MOVED 'OFF.'  INV SHOWED LEFT SEAT PLT HAD TRNG IN LATER MODELS (LEARJET 24/25); BUT ONLY A BIENNIAL FLT REVIEW WAS NOTED IN THE MODEL 23. COMPANY DISPATCHER SAID NO TRNG WOULD HAVE BEEN PERFORMED ON ACDNT FLT (WITH PSGR ABOARD). ACFT WAS ABT 430 LBS OVR MAX WT LMT.

## Aircraft

- Registration: [N959SC](https://openairdocs.org/deregistered/N959SC-2013-06-11), registration cancelled 2013-06-11, S/N 045A (OpenAirDocs)
- Reported make and model: LEARJET 23
- Registry model: [Learjet 23](https://openairdocs.org/model/learjet-23) (registry code 5170102) (OpenAirDocs)
- Registry engine: [GE CJ610-SER series](https://openairdocs.org/engine/ge-cj610-ser-series) (registry code 30006, turbo-jet) (OpenAirDocs)
- Category: Airplane
- Serial number: 23-045A
- Engines: GE CJ-610-4 2850 lbs thrust turbo jet
- Damage: Destroyed
- Fire: On-Ground
- Flight: Positioning, Part 91
- Operator: Jetstream International, Inc.
- Departed: DET
- Destination: MDW, CHICAGO, IL
- Flight plan: IFR
- Airport: DET, Detroit City, runway 33, 5,147 × 100 ft, asphalt

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 43; commercial, airline transport; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 1, valid medical--no waivers/lim.; toxicology performed; flight hours: 9,000 total, 2,600 in this make and model

## Weather

- Conditions: Visual (VMC), Dusk
- Wind: 240° at 10 knots
- Visibility: 7 statute miles
- Lowest ceiling: 10,000 ft overcast
- Temperature: -0 °F, dew point -0 °F
- Observed at: DET, 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 19910722029029A](https://openairdocs.org/incident/19910722029029A), Jul 22, 1991: Lear 23LEAR, Detroit, MI, Destroyed, 3 fatal. Over gross and parking brake not fully released. Used all runway. Lifted nose high. Hit trees. Needed longer runway

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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