Northwest Airlines Flight 48
McDonnell Douglas DC-10-40 · Incident: airframe, component or system failure en route
From an unrecorded airport to Boston Logan International Airport (BOS)
Event
- NTSB case
- CHI93IA248
- Event typeAccident: someone killed or seriously injured, or the aircraft substantially damaged (NTSB definition). Incident: an occurrence that affected or could have affected safety, short of that. Glossary
- Incident
- InvestigationHow far the investigation had got when the record was published: preliminary, ongoing, final or completed. Unknown where the source does not say. Glossary
- Completed
- API-reported fatalities
- 0 · all aircraft and ground
- Ground fatalities
- 0
- OperationWhat kind of flying it was, grouped by the rules it flew under: airline (US Part 121), air taxi and commuter (Part 135), general aviation (Part 91 and similar), military or government. Glossary
- Airline
- WeatherVisual meteorological conditions (VMC): good enough to fly by looking outside. Instrument conditions (IMC): cloud or low visibility, flying by instruments. Glossary
- Visual Meteorological Cond
McDonnell Douglas DC-10-40
- Aircraft type
- McDonnell Douglas DC-10
- Category
- Airplane
- RegistrationThe aircraft's tail number, such as N12345 or G-ABCD. Registrations are reissued, so the same one years apart can be a different aircraft. Glossary
- N158US
- Operator
- Northwest Airlines
- Onboard fatalities
- Unknown
- Route
- From not recordedTo Boston Logan International Airport (BOS), Boston, MA
- Aircraft age
- Not recorded
- Flight rulesThe regulations the flight operated under: in the US, Part 91 (general aviation), Part 121 (airlines), Part 135 (air taxi and commuter) and others; for flights abroad, the NTSB's coarser commercial or non-commercial code. Glossary
- Part 121: Air Carrier
- Phase of flightThe stage of the flight when things started to go wrong: standing, taxi, takeoff, initial climb, en route, maneuvering, approach or landing. Glossary
- En route · climb to cruise
- First occurrenceThe single coded event the NTSB judges best describes what happened (records from 2008 on). Older records name the first occurrence in the sequence instead. Glossary
- Airframe, component or system failure
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- None
Cause areas
- Comm/nav equipment › Failure, partial
- Reason for occurrence undetermined
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
WHILE CLIMBING THROUGH 20,000 FEET THE #1 INS FAILED. THE GYRO OUTPUT VARIED AS THE GYRO TUMBLED, WHICH PRODUCED A BANK ANGLE SIGNAL. THE FAILURE MODE ALLOWED THE BANK ANGLE INFORMATION TO BE TRANSMITTED TO THE YAW FLIGHT GUIDANCE COMPUTER, ALLOWING THE ATTITUDE MONITORING AND SWITCHING UNIT TO MOVE THE LOWER RUDDER HYDRAULIC ACTUATOR, CAUSING THE LOWER RUDDER TO MOVE.
Probable cause
the failure of a navigation system (#1 INS) for reason or reasons undetermined.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record CHI93IA248
- Event ID
- 20001211X12828
- Case number
- CHI93IA248
- Dataset
- historical-pre2008
- Source SHA-256
- 89e2df6d848e7ab3b42e7d7c7a03ff403303057a26ca04c95b3ea67201c3ce74
Source notes (5)
- Unreviewed is an editorial label, not an investigation status. API-sourced is not report-checked or human-reviewed. Explicit event totals are used without summing aircraft injury tables; onboard allocation is withheld. Unknown values remain unknown. The operation category is mapped from the NTSB-reported FAR part and has not been reviewed.
- Filled from the NTSB case API where the bulk record had no value: investigation status, damage. Values present in the bulk record are kept.
- The date is the local date, which is the same as the UTC date the NTSB stores.
- API snapshot SHA-256: def0adef12e156c50db388996bbd55498ccc160b7747826ae0532e05c7e93f5c; retrieved 2026-09-18T18:33:30.884Z.
- The NTSB's operator name is blank for N158US; the operator shown is the name the NTSB's other records give its FAA operator code, NWAA.