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NTSB Report
July 10, 1991 · Air Tractor AT-401 · N4538K
Calexico, CA
Overview
Report Status
Probable Cause
Event Type
Accident
Date
July 10, 1991
Injury Outcomes
1 injury (1 minor injury)
Location
Calexico, CA
Aircraft
Air Tractor AT-401
Tail Number
N4538K
Operator
Frontier Ag Service
Injuries
Minor
Aircraft Damage
Destroyed
NTSB Number
LAX91LA302
THE INVESTIGATION REVEALED THAT DURING THE DAY ON JULY 9TH, WORKERS FROM THE IMPERIAL COUNTY IRRIGATION DISTRICT ERECTED A LARGE CAUTION SIGN ON THE DEPARTURE RUNWAY ABOUT ONE THIRD OF THE WAY FROM THE START. THAT NIGHT THE PILOT ARRIVED AT THE AIRPORT FOR HIS NIGHT SPRAY RUN AND HE WAS UNAWARE OF THE NEWLY PLACED SIGN. AFTER LOADING THE CHEMICALS TO BE SPRAYED ON BOARD THE AIRCRAFT, THE PILOT TOOK OFF AND THE AIRCRAFT STRUCK THE SIGN WITH THE LEFT SPRAY BOOM. THE BOOM WAS TORN LOOSE FROM THE STRUCTURE, HOWEVER, DID NOT SEPARATE TOTALLY AND BEGAN TO FLAP IN THE AIRSTREAM AS CHEMICALS POURED FROM THE HOPPER. THE PILOT TURNED THE AIRCRAFT TO RETURN TO THE AIRSTRIP AS HE REACHED FOR THE EMERGENCY SHUTOFF VALVE TO STOP THE FLOW OF CHEMICALS. AS THE AIRCRAFT NEARED THE AIRSTRIP, IT COLLIDED WITH A STACK OF HAY BALES RECENTLY ERECTED NEAR THE RUNWAY.
NTSB Probable Cause
THE ERECTION OF A CONSTRUCTION SIGN ON AN ACTIVE RUNWAY BY COUNTY WORKERS WITHOUT NOTIFYING THE AIRPORT OPERATORS, AND, THE INABILITY OF THE PILOT TO DETECT THE PRESENCE OF THE SIGN DURING THE DARK NIGHT TAKEOFF.
Full Narrative
THE INVESTIGATION REVEALED THAT DURING THE DAY ON JULY 9TH, WORKERS FROM THE IMPERIAL COUNTY IRRIGATION DISTRICT ERECTED A LARGE CAUTION SIGN ON THE DEPARTURE RUNWAY ABOUT ONE THIRD OF THE WAY FROM THE START. THAT NIGHT THE PILOT ARRIVED AT THE AIRPORT FOR HIS NIGHT SPRAY RUN AND HE WAS UNAWARE OF THE NEWLY PLACED SIGN. AFTER LOADING THE CHEMICALS TO BE SPRAYED ON BOARD THE AIRCRAFT, THE PILOT TOOK OFF AND THE AIRCRAFT STRUCK THE SIGN WITH THE LEFT SPRAY BOOM. THE BOOM WAS TORN LOOSE FROM THE STRUCTURE, HOWEVER, DID NOT SEPARATE TOTALLY AND BEGAN TO FLAP IN THE AIRSTREAM AS CHEMICALS POURED FROM THE HOPPER. THE PILOT TURNED THE AIRCRAFT TO RETURN TO THE AIRSTRIP AS HE REACHED FOR THE EMERGENCY SHUTOFF VALVE TO STOP THE FLOW OF CHEMICALS. AS THE AIRCRAFT NEARED THE AIRSTRIP, IT COLLIDED WITH A STACK OF HAY BALES RECENTLY ERECTED NEAR THE RUNWAY.
Flight
Event TypeAccident
Event Time23:30 PDT
Nearest Airport0nm
Runway0
Flight Plan FiledNone
Aircraft FireNo
Aircraft ExplosionNo
Aircraft
AircraftAir Tractor AT-401
Tail NumberN4538K
Aircraft CategoryAir
DamageDestroyed
OperatorFrontier Ag Service
Operating RulePart 137
Engines1
Engine TypeReciprocating
Engine DetailsP&W · R-1340 · Reciprocating · 600
Seats1
People & Injuries
Injury Summary1 injury (1 minor injury)
Fatal0
Serious0
Minor1
Uninjured0
Total1
Crew 1Age 55 · Second Class
Conditions
ConditionsVMC
LightDark Night
Wind250° @ 6 kt
Visibility30 sm
CeilingNone
Temperature / Dew Point0 C
Altimeter0
Weather SourceWIT