# NTSB Incident OPS18IA015
> **BOEING 747** · 2018-06-21 · Chicago, IL, USA · NONE
## Event
- **NTSB number:** OPS18IA015
- **Event ID:** 20180622X92612
- **Type:** Incident
- **Date:** 2018-06-21
- **Location:** Chicago, IL, USA
- **Coordinates:** 41.969444, -87.918609
## Injuries
- **Highest injury:** NONE
- **Fatal:** 0
- **Serious:** 0
- **Minor:** 0
- **Uninjured:** 4
- **Total aboard:** 4
## Aircraft
- **Make:** BOEING
- **Model:** 747
- **Registration:** B-18711
- **FAR Part:** NUSC
- **Engines:** —
- **Damage:** —
## Conditions
- **Light:** DAYL
- **Weather:** IMC
## Probable cause

Interference with the localizer signal resulting in a Multipath condition experienced by CAL5148 while conducting an ILS CAT III (autoland) approach. This condition resulted in a runway excursion and subsequent go-around. The interference was most likely caused by a previous departure flying through the ILS critical area while departing the same runway.

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*Source: [NTSB CAROL](https://data.ntsb.gov/carol-main-public/basic-search?source=ntsb&type=event&ntsb_number=OPS18IA015) · AI Analytics · CC0 1.0*