Boeing 747SR-146B SF incident near Anchorage, Alaska, December 5, 2004
On December 5, 2004 at about 6:00 pm local time, a Boeing 747SR-146B SF, registered JA8158, suffered minor damage in an incident near Anchorage, Alaska. It was flown under foreign airline rules (Part 129). No one was hurt; 3 people were on board or involved. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
The fatigue and subsequent fracture of a portion of the airplane's pressure bulkhead, which resulted in a rapid decompression during cruise flight.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- December 5, 2004 · about 6:00 pm local time
- Place
- Anchorage, Alaska · map
- Type
- Incident
- Injuries
- No one was hurt; 3 people were on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Boeing 747SR-146B SF · all 747SR-146B SFs on the register
- Registration
- JA8158 · no longer on the register · serial 22711
- Damage
- Minor damage
- Flight
- Flight · foreign airline rules (Part 129)
The NTSB's narrative final · quoted from the NTSB record
The 14 CFR Part 129 non-scheduled international cargo flight had a rapid decompression at 30,000 feet msl, and returned to the takeoff airport. An examination revealed an elliptical tear in the right side of the pressure bulkhead web separating the electronics service bay from the nose wheel well. The tear extended about 12-inches along a horizontal rivet line, with both ends of the torn skin turned downward approximately 80-90 degrees. The damaged area (STA 260-280, WL 160-170) was excised from the structure, and an examination of the fracture mechanism was conducted. The fracture examination disclosed that the web fracture was initiated by fatigue from multiple origins on the outboard web surface within the pressure vessel. Ten separate fatigue cracks propagated through the full web thickness before the onset of rapid ductile tearing. Each fatigue crack formed adjacent to a fastener hole common with the WL 170 beam, and was in line with the edge of the bonded strip doublers on the inboard surface (wheel well side). The web material met all the engineering specifications. At the time of the incident, the airplane had logged 58,185 flight hours, and 27,243 cycles/landings. Inspection criteria for the affected area is contained in a manufacturer's Service Bulletin and their Alert Revisions 1 thru 4. Following the examination of the incident airplane, Alert Revision 4 was amended to specify more frequent inspections of the affected area.
The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.
The factual record from the NTSB's investigation tables, in plain English
Pilot
- Certificate: foreign licence
- Ratings: multi-engine land; single-engine land; instructor: airplane multi-engine; instructor: airplane single-engine; instructor: instrument airplane; instrument: airplane
- Flight time: 17,678 hours in all; 4,370 in this make and model; 133 in the last 90 days; 69 in the last 30 days; 13,649 as pilot in command
- Medical certificate: Class 1
- Seat: left
- Injury: no injuries
Co-pilot
- Certificate: foreign licence
- Ratings: multi-engine land; single-engine land; instructor: airplane multi-engine; instructor: airplane single-engine; instrument: airplane
- Flight time: 5,673 hours in all; 2,584 in this make and model; 161 in the last 90 days; 46 in the last 30 days; 101 as pilot in command
- Medical certificate: Class 1
- Seat: rgt
- Injury: no injuries
Flight Engineer
- Certificate: foreign licence
- Seat: rear
- Injury: no injuries
The aircraft
- Airframe total time: 58,179 hours
- Last inspection: continuous airworthiness programme
- Maximum gross weight: 750,000 lb
- Seats: 13
- Landing gear: retractable
- Engine: General Electric CF6-50E2 (turbofan); 0 hours total
The flight
- Departed from: PANC Anchorage AK
- Destination: NRT Tokyo-Narita
- Flight plan: IFR
- A second pilot was aboard
Weather at the time
- Light: daylight
- Wind: from 030° at 5 knots
- Visibility: 7 statute miles
- Sky: broken clouds at 1,100 ft; scat at 400 ft
- Temperature: 12°F (-11°C), dew point 10°F (-12°C)
- Altimeter: 29.64 inHg
- Observation at 5:53 pm from PANC
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Crew | 3 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
The docket, the folder of records gathered during an investigation (maintenance records, photographs, witness statements, examinations), has not been read from the NTSB for this case yet; the list appears here once it has. Open the docket at the NTSB.
Everything on this page comes from the NTSB's public records. The narrative, probable cause and findings are the NTSB's own words; the coded tables behind the report are written out in plain English, with pilots' ages, home towns and medical details left out. The documents and photographs are the NTSB's docket, shown as the NTSB released them. This site's own text never names anyone involved. A preliminary report can change; the final report usually follows one to two years later, and the page is refreshed when it does.