Boeing 747 B-18711

Summary

On 21 June 2018 at about 14:58 local time, a Boeing 747 registered B-18711, operated by China Airlines Ltd, was involved in an incident near Chicago, Illinois, United States. 4 people were on board and nobody was injured. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

21 June 2018 at 14:58

Classification

Incident

Location

Chicago, Illinois, United States

Nearest airport

Chicago O'Hare Intl Airport (KORD)

Coordinates

41.9694, -87.9186

Aircraft

Boeing 747

Registration

B-18711

Category

Airplane

Operator

China Airlines Ltd

Operating rule

Non-U.S., Commercial

Purpose of flight

Unknown

Phase of flight

Not recorded

Route

Anchorage → Chicago

Aircraft damage

Not recorded

Weather

IMC

Light

Day

NTSB number

OPS18IA015

Nobody was injured.

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.

Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.

Read the full NTSB narrative

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).

Quoted verbatim from the NTSB record.