On April 21st an Air Canada Boeing 787-9 flying from Vancouver to Hong Kong descended below the minimum sector altitude as it approached Hong Kong International’s runway 25L for landing. The tower issued a terrain warning, after which the crew corrected their flight path, re-intercepting the localizer and performing a safe landing. This event is the latest in a series of ILS-related incidents at the airport.
Incident details
The Air Canada aircraft involved was a Boeing 787-9 with registration C-FNOH. It was performing flight AC-2287, which departed on April 20th from Vancouver, BC (Canada) for Hong Kong International Airport.
The Aviation Herald reports that there were four crew onboard the aircraft, which was cleared for ILS approach to runway 25L. Shortly after passing waypoint LOTUS, the aircraft was observed overshooting the localizer and descending to 3900 feet, this is below the minimum sector altitude of 4300 feet. As a result, a terrain warning was issued and the crew corrected their flight path to re-intercept the localizer, continuing on to make a safe landing.
Days later, on April 24th, the Canadian Transportation Safety Board reported that the flight crew had reported a false capture of the ILS runway 25L. The Aviation Herald also reports that the operator, Air Canada, is conducting an internal assessment.
A series of similar incidents
This is just the latest in a string of similar occurrences involving Boeing 787 aircraft at Hong Kong International Airport. Simple Flying has made a note of these:
- October 19th, 2019: A second Virgin Atlantic 787-9 descended below its ‘minimum safe sector altitude’
- September 29th, 2019: A Virgin Atlantic 787-9 deviated from localizer and descended below minimum safe altitude.
- September 7th, 2019: An Etihad 787-9 veered off localizer and descended below safe height on ILS approach.
- July 18th, 2019: Ethiopian 787-8 experienced a loss of control on ILS approach.
Simple Flying has contacted Hong Kong’s Civil Aviation Department with a request for comment. No response was received at the time of publication.
As we had reported with Virgin Atlantic’s October incident, the four previous occurrences took place in the same vicinity – around waypoint RIVER. In this latest occurrence, the aircraft had just passed waypoint LOTUS – which is only 1.5 km from RIVER.
Interestingly, information was found on Hong Kong Aeronautical Information Services’ (AIS) website. It acknowledges the possibility of glide path (GP) signal interference that may arise:
10.6 Pilots are warned that during ILS CAT I operations RWY 07R and RWY 25L GP signals may be liable to interference from aircraft taxiing in the vicinity of the GP aerial. Pilots should therefore closely monitor their ILS approach profile and rate of descent.
The AIS webpage also states the following:
Pilots are reminded that use of the ILS signals outside of the following coverage areas may lead to false capture or reverse sense indications:
| RWY | LOC Coverage Area | GP Coverage Area |
|---|---|---|
| RWY 07L | Standard left of LOC course | Standard left and right of RWY centreline |
| 17 NM within 28° right of LOC course and 25 NM within 10° right of the LOC course | ||
| RWY 07R | 17 NM within 25° left of LOC course and 25 NM within 10° right of the LOC course | Standard left and right of RWY centreline |
| 17 NM within 19° right of LOC course and 25 NM within 10° right of the LOC course | ||
| RWY 25L | 17 NM within 28° left of LOC course and 25 NM within 10° left of the LOC course | 15 NM within 7° left of RWY centreline |
| Standard right of LOC course | Standard right of RWY centreline | |
| RWY 25R | Standard left of LOC course | Standard left of RWY centreline |
| Between 20 NM – 25 NM within 4° right of LOC course below 5 500 ft | 15 NM within 6° right of RWY centreline |
Conclusion
It is highly peculiar that this same type of occurrence is happening with the same type of aircraft around the same geographical location. There have been other aircraft types descending too low but the 787 seems to be more common. Without a doubt, this is on the Hong Kong Civil Aviation Department’s radar.
As commenters on previous articles have said, it is interesting that it is only the 787 not other similarly equipped aircraft. The possibility of specific receiver placement on the 787 in combination with Hong Kong’s terrain on certain approach vectors has been raised by several people as something worth investigating.
To all the pilots out there, let us know your thoughts in the comments on this latest occurrence and what could be done to solve the issue.
