CHI98GA025 · Aerospatiale AS350B
Illinios State Police Aerospatiale AS350B · Accident: in flight collision with terrain/water while maneuvering
From Chicago Midway International Airport (MDW) to C18
Event
- NTSB case
- CHI98GA025
- 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
- Accident
- 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
- 2 · 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
- General aviation
- 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
Aerospatiale AS350B
- Aircraft type
- Aerospatiale AS350
- Category
- Helicopter
- 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
- N911RR
- Operator
- Illinios State Police
- Onboard fatalities
- Unknown
- Route
- From Chicago Midway International Airport (MDW), Chicago, ILTo C18
- 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 91: General Aviation
- 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
- Maneuvering
- 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
- In flight collision with terrain/water
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- Destroyed
Cause areas
- Pilot in command(cfi) › Clearance, misjudged
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
A witness reported that he was watching the helicopter traveling in an easterly direction flying low above the building when it circled back in a westerly direction somewhere around the east end of the runway. While heading west above the runway it looked like it was getting ready to land. He said that when the helicopter was about 5 to 10 feet above the ground he turned his back getting into his car. He heard an explosion and then a second explosion and when he turned around he saw the flames from above the truck which was parked between the airport and his car. He said he then took a few steps to the east and then saw the helicopter in flames. The helicopter was destroyed on impact with the terrain and a post-crash-fire alongside runway 09/27. A post accident examination of the helicopter disclosed no evidence of any pre-existing anomaly with the helicopter or the engine.
Probable cause
the pilot in command misjudged the clearance with the terrain during a dark night maneuvering approach to a runway. A related factor was the dark night conditions.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record CHI98GA025
- Event ID
- 20001208X08960
- Case number
- CHI98GA025
- Dataset
- historical-pre2008
- Source SHA-256
- 89e2df6d848e7ab3b42e7d7c7a03ff403303057a26ca04c95b3ea67201c3ce74
Source notes (4)
- 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. 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: 105dcc4c3ed8b20ec1397d68e6061cad9fbf456c5a27cf465175f760453431b5; retrieved 2026-09-20T22:46:20.278Z.