Boeing 747 incident near Chicago, Illinois, June 21, 2018
On June 21, 2018 at about 2:58 pm local time, a Boeing 747, registered B18711, was involved in an incident during landing (aborted after touchdown) near Chicago, Illinois (Chicago O'Hare Intl Airport). It was a flight of an unrecorded kind under non-U.S. commercial rules. No one was hurt; 4 people were on board or involved. The weather was instrument conditions (cloud, fog or low visibility).
The NTSB's probable cause their words, unchanged
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.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- June 21, 2018 · about 2:58 pm local time
- Place
- Chicago, Illinois · Chicago O'Hare Intl Airport · map
- Type
- Incident
- Injuries
- No one was hurt; 4 people were on board or involved.
- Weather
- instrument conditions (cloud, fog or low visibility)
- Aircraft
- Boeing 747 · all 747s on the register
- Registration
- B18711 · no longer on the register · serial Foreign
- Damage
- Not recorded
- Flight
- Flight of an unrecorded kind · non-U.S. commercial rules
The NTSB's narrative final · quoted from the NTSB record
CAL5148 was conducting an ILS autoland approach to runway 10R. Instrument meteorological conditions prevailed at the time of the incident, with an overcast ceiling of 600 feet above ground level (agl), and visibility of 2 and 1/2 miles with moderate rain. These conditions required protection of the ILS critical area by ATC which they did according to FAA Order JO 7110.65, Air Traffic Control. ATC issues control instructions to protect ILS critical areas and avoid signal interference from vehicle traffic and taxiing aircraft when the reported weather is a ceiling of less than 800 feet or visibility of less than 2 miles. However, this restriction does not include consideration for preceding arriving or departing aircraft. While a previously departed aircraft was airborne and over the ILS critical area, CAL5148 experienced localizer deviations while on short final. In math modelling analysis of this event conducted by the FAA; the results were consistent with the localizer deviations determined from CAL5148 flight data recorder (FDR) data. Specifically, the modelling indicated the deviation beginning at 1/4 mile from threshold would lead the aircraft to turn left to continue to follow the localizer course line during an autoland approach. The FAA National Resource Engineer for Navigation who performed the modelling wrote “I am 90% confident that the location of departing ENY3544 caused sufficient Multipath (signal deflection) to produce a fly left indication to arriving CAL5148.” “Multipath” is a term used to describe the distortion of the radiated signal which is caused by the signal being deflected off either stationary or moving objects such as aircraft or vehicles in the localizer or glide slope critical area(s).
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
What happened, in order
- Runway excursion during landing
- Miscellaneous/other during landing
- Miscellaneous/other during landing (aborted after touchdown) defining event
The NTSB's findings
- cause Environmental issues › Operating environment › Approach aid coverage/avail › Localizer › Effect on equipment
The aircraft
- Landing gear: fixed
- Operator: China Airlines LTD
The flight
- Departed from: ANC Anchorage AK
- Destination: KORD Chicago IL
- Flight plan: IFR
- Runway 10L, 13,000 ft by 150 ft
- A second pilot was aboard
Weather at the time
- Light: daylight
- Wind: from 060° at 12 knots
- Visibility: 2.5 statute miles
- Sky: overcast at 600 ft
- Temperature: 66°F (19°C), dew point 64°F (18°C)
- Altimeter: 29.78 inHg
- Observation at 2:51 pm from KORD
Weather report (METAR): METAR KORD 211451Z 06012KT 2 ½SM RA BR OVC006 19/18 A2978 RMK AO2 LTG DSNT E SLP080 P0025 60056 T01890178 58001=
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight crew | 4 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
The NTSB has not released the docket for this case yet. The docket, the folder of records gathered during an investigation (maintenance records, photographs, witness statements, examinations), is usually released when the investigation is nearly complete, and the list here is refreshed when it appears. Check 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.