Brownsville/South Padre Airport
Aircraft Accident/Incident Report

Brownsville, Texas 78521
Wednesday, April 29, 1998 21:00 CDT

NTSB Narrative Summary Released at Completion of Accident

While taxiing to takeoff, all four occupants of the DC-8 freighter became short of breath. They donned oxygen masks, and the flight returned to the ramp. Cargo included 960 pounds of dry ice (solid carbon dioxide) in 198 separate 4.85-pound blocks, used as a refrigerant for frozen shrimp. Sublimation of dry ice to the gaseous state occurs constantly. When the carbon dioxide (CO2) gas concentration reaches 0.5% shortness of breath may occur, at 2%, depth of respiration increases, and above 4%, breathing becomes rapid and very deep. At sea level and 70 degrees F (incident conditions were 23 feet msl and 66 degrees F), 0.4 pounds of CO2 gas in the cockpit of a DC-8 produces a 0.5% concentration and 3.3 pounds produces a 4% concentration. In 10 minutes, at sublimation rates of 1% and 14% per hour, 960 pounds of dry ice produces 1.6 and 22.4 pounds of CO2 gas, respectively. The 1% sublimation rate is commonly used when calculating amounts of dry ice that can safely be carried on aircraft; however, it was determined for bulk shipments of dry ice and may not be applicable to dry ice used as a refrigerant. The 14% rate was determined using a single 5 pound block of ice.

NTSB Probable Cause Narrative

The flightcrew experienced physical impairment resulting from an accumulation in the cockpit of carbon dioxide fumes produced by dry ice, a hazardous material, carried in the main cargo compartment.

Event Information

Type of Event Incident
Event Date 4/29/1998
Event Day of the Week Wednesday
Time of Event 2100
Event Time Zone Central Daylight Time
Event State TEXAS
Event Country --
Zipcode of the event site 78521
Event Date Year 1998
Event Date Month 4
MidAir Collision Indicator No
On Ground Collision occurred ? No
Event Location Latitude --
Event Location Longitude --
Event Location Nearest Airport ID BRO
Indicates whether the acc/inc occurred off or on an airport On Airport
Distance from airport in statute miles --
Degrees magnetic from airport --
Airport Elevation 23
Weather Briefing Completeness Unknown
Investigator's weather source Weather Observation Facility
Time of the weather observation 2056 Central Daylight Time
Direction of event from weather observation facility (degrees) 0
Weather Observation Facility ID BRO
Elevation of weather observation facility 23
Distance of event from weather observation facility (units?) 0
Time Zone of the weather observation CDT
Lighting Conditions Night/Bright
Lowest Ceiling Height 0
Lowest Non-Ceiling Height 0
Sky/Lowest/Cloud Conditions Clear
Sky Condition for Lowest Ceiling None
Visibility Runway Visual Range (Feet) 0
Visibility Runway Visual Value (Statute Miles) 0
Visibility (Statute Miles) 10
Air Temperature at event time (in degrees celsius) 19
Dew Point at event time (in degress fahrenheit) 15
Wind Direction (degrees magnetic) 50
Variable Wind Indicator Unknown
Wind Speed (knots) 5
Wind Velocity Indicator Unknown
Wind Gust Indicator Not Gusting
Wind Gust (knots) 0
Altimeter Setting at event time (in. Hg) 30
Density Altitude (feet) --
Intensity of Precipitation Unknown
METAR weather report --
Event Highest Injury Minor
On Ground, Fatal Injuries 0
On Ground, Minor Injuries 0
On Ground, Serious Injuries 0
Injury Total Fatal --
Injury Total Minor 4
Injury Total None --
Injury Total Serious --
Injury Total All 4
Investigating Agency NTSB
NTSB Docket Number (internal use) 5006
NTSB Notification Source --
NTSB Notification Date Apr 30 1998 12:00AM
NTSB Notification Time 930
Fiche Number and/or location -used to find docket information IMAGE
Date of most recent change to record Feb 23 2001 1:55PM
User who most recently changed record dbo
Basic weather conditions Visual Meteorological Cond
FAA District Office --

Aircraft Involved

Aircraft #1

Aircraft Registration Number N507DC
NTSB Number FTW98IA196
Missing Aircraft Indicator N
Federal Aviation Reg. Part Part 121: Air Carrier
Type of Flight Plan filed IFR
Flight plan Was Activated? --
Damage None
Aircraft Fire None
Aircraft Explosion None
Aircraft Manufacturer's Full Name Douglas
Aircraft Model DC-8-51
Aircraft Series Identifier DC-8-51
Aircraft Serial Number 45855
Certified Max Gross Weight 315000
Aircraft Category Airplane
Aircraft Registration Class U.S. Registered/U.S. Soil
Aircraft is a homebuilt? No
Flight Crew Seats --
Cabin Crew Seats --
Passenger Seats --
Total number of seats on the aircraft 4
Number of Engines 4
Fixed gear or retractable gear Retractable
Aircraft, Type of Last Inspection Continuous Airworthiness
Date of Last Inspection Apr 28 1998 12:00AM
Airframe hours since last inspection 7
Airframe Hours 3636
ELT Installed Yes
ELT Activated No
ELT Aided Location of Event Site Unknown
ELT Type --
Aircraft Owner Street Address PO BOX 524236
Aircraft Owner City MIAMI
Aircraft Owner State FL
Aircraft Owner Country
Aircraft Owner Zipcode 33152
Operator is an individual? --
Operator Same as Owner? No
Operator Is Doing Business As --
Operator Address Same as Owner? No
Operator Street Address 4600 NW 36TH ST, BLDG 22
Operator City MIAMI
Operator State FL
Operator Country
Operator Zip code 33122
Operator Code FXLA
Owner has at least one certificate Yes - certificate holder
Other Operator of large aircraft? No
Certified for Part 133 or 137 Operation Unknown
Operator Certificate Number --
Indicates whether an air carrier operation was scheduled or not Non-scheduled
Indicates Domestic or International Flight Domestic
Operator carrying Pax/Cargo/Mail Cargo
Type of Flying (Per_Bus / Primary) Unknown
Second Pilot on Board Yes
Departure Point Same as Event Yes
Departure Airport Code BRO
Departure City
Departure State
Departure Country
Departure Time 0
Departure Time Zone
Destination Same as Local Flt --
Destination Airport Code LRD
Destination City LAREDO
Destination State TX
Destination Country
Specific Phase of Flight --
Report sent to ICAO? --
Evacuation occurred --
Date of most recent change to record Feb 23 2001 1:55PM
User who most recently changed record dbo
Since inspection or accident --
Event Location Runway Number and Location 0
Runway Length --
Runway Width --
Sight Seeing flight No
Air Medical Flight No
Medical Flight --