Northwest Airlines Boeing 747-227B incident
Boeing 747-227B and Air Wisconsin British Aerospace BAE 146-200 BAE 146-20 · Incident: near collision between aircraft during initial climb
Event
- NTSB case
- CHI88IA073
- 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
Aircraft 1 · Boeing 747-227B
- Aircraft type
- Boeing 747
- 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
- N635US
- Operator
- Northwest Airlines
- Onboard fatalities
- Unknown
- Route
- From not recordedTo Tokyo, JAPAN
- 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
- Initial climb
- 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
- Near collision between aircraft
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- None
Aircraft 2 · British Aerospace BAE 146-200 BAE 146-20
- Aircraft type
- British Aerospace BAE-146
- 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
- N602AW
- Operator
- Air Wisconsin
- Onboard fatalities
- Unknown
- Route
- From not recordedTo Appleton International Airport (ATW), Appleton, WI
- 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
- Initial climb
- 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
- Near collision between aircraft
- 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
- Atc personnel(supervisor) › Crew/group coordination, inadequate
- Control tower service › Inadequate
Approximate · Estimated position: the centre of Chicago, IL, the place the record names. Not the accident site.
NTSB narrative
NORTHWEST FLT 3 (BOEING 747, N635US) WAS CLRD TO TAKEOFF ON RWY 14R AT THE SAME TIME AIR WISCONSIN FLT 925 (BAE 146, N602AW) WAS CLRD TO TAKEOFF ON RWY 22L AT THE CHICAGO-O'HARE INTL ARPT. SUBSEQUENTLY, THE TWO ACFT PASSED WITH AN ESTIMATED 3000 TO 4000 FT SEPARATION. THIS OCCURRED AFTER THE TOWER SUPERVISOR HAD NOT ASSURED COORDINATION BETWEEN THE NORTH & SOUTH LOCAL CONTROL POSITIONS. AT THE TIME OF THE OPERATIONAL ERROR, THE TOWER SUPERVISOR WAS ACTING AS BOTH THE SUPERVISOR & THE TOWER CAB COORDINATOR.
Probable cause
FAILURE OF THE TOWER CAB SUPERVISOR TO ASSURE THAT COORDINATION BETWEEN THE SOUTH LOCAL CONTROLLER AND NORTH LOCAL CONTROLLER HAD BEEN COMPLETED. A FACTOR IS THE FAILURE OF FAA TOWER MANAGEMENT TO INSURE THERE WERE PERSONNEL MANNING THE CAB COORDINATOR POSITION.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record CHI88IA073
- Event ID
- 20001213X25026
- Case number
- CHI88IA073
- Dataset
- historical-pre2008
- Source SHA-256
- 89e2df6d848e7ab3b42e7d7c7a03ff403303057a26ca04c95b3ea67201c3ce74
Source notes (6)
- 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: 640c70738794593237b3081b56306eb84712315b862c5e6968a65e8d4fcb2b1d; retrieved 2026-09-18T19:27:08.226Z.
- The NTSB's operator name is blank for N635US; the operator shown is the name the NTSB's other records give its FAA operator code, NWAA.
- Corrected after a review of the NTSB narrative, which states these values explicitly: operator. The NTSB narrative names the operator: "AIR WISCONSIN FLT 925 (BAE 146, N602AW) WAS CLRD TO TAKEOFF ON RWY 22L"