24left

Ooooh, I just realized I have my own "hard landing but parts intact" collector's item,

CZAMFlyer

It seems many people may still be confused due to a pair of similar events involving AC A320s, both in SFO: the taxiway C overflight and the landing on the runway after repeated tower instructions to go around.
We can also debate the term "accident investigation" as it relates to AC15's bum slide arrival.

24left

We can.

Someone else called it an accident. I was just along for the ride.


​​​​​​​

24left

It seems AC is sending emails. I know others who also just received this too.

Quote:

"Please accept my sincere regrets for your flight AC15 from Toronto to Hong Kong on December 10th, 2018. As I am sure you are aware the flight encountered wind shear on approach in Hong Kong. "

The email says a few other things and also thanks us for our understanding and support etc. An eCoupon was included, a gesture of goodwill.

Say what you will, but it was pro-active on AC's part.

jc94

tracon

Now 350ish oblivious passengers are going to find out things weren't as they seemed.

The weather sequences and photos are not indicative of wind shear.
Maybe mechanical turbulence from the maintenance hangars near the threshold.

24left

There is some interesting reading from the Hong Kong Weather Observatory in the subject of Terrain-induced wind shear at HKIA, including some nice charts/graphics:

"According to the Observatory's statistics, about 1 in 500 flights landing at or departing from the Hong Kong International Airport (HKIA) reported encountering significant windshear, whereas about 1 in 2,500 flights reported encountering significant turbulence. The majority of significant windshear events at HKIA could be associated with terrain disruption of airflow..."

https://www.weather.gov.hk/m/article...itle=ele_00457


And from the Royal Meteorological Society (including a nice map):

"At Hong Kong International Airport (HKIA) (Figure 1), significant low‐level wind shear is reported once in every 400–500 flights and could be due to terrain‐disrupted airflow (the majority of cases), sea breeze, thunderstorms and low‐level jets."

"....Most wind shear reported by pilots at HKIA has a magnitude of 15–25 kn, accounting for 97.7% of all the reports received so far (since the opening of HKIA in 1998, up to 2015). However, occasionally the reported wind shear magnitude can reach 30 kn or more (about 2.3% of all the wind shear reports)."

https://rmets.onlinelibrary.wiley.co....1002/met.1637


*****
Disclaimer: No, I am also not a weather expert, but considering I had a "different" experience on my AC 15 flight, and considering I've never had this experience in a lifetime of flying on AC, I'm curious.

@tracon
Can you offer enlightenment from your professional POV?

tracon

These aren't generally the METARs associated with wind shear.
What you see is steady wind, altimeter and temperature, no convective activity.
The weather is being taken every 30 minutes.
No special weather observations indicating an important change in conditions.

VHHH 110800Z 33014KT CAVOK 18/10 Q1020 NOSIG=
VHHH 110730Z 34013KT 9999 FEW040 18/10 Q1020 NOSIG=
VHHH 110700Z 33016KT 9999 FEW040 18/10 Q1020 NOSIG=
VHHH 110630Z 33012KT 9999 FEW040 18/10 Q1020 NOSIG=
VHHH 110600Z 34011KT 9999 FEW028 18/10 Q1020 NOSIG=
VHHH 110530Z 33011KT 9999 FEW028 18/10 Q1020 NOSIG=
VHHH 110500Z 33012KT 9999 FEW025 17/10 Q1020 NOSIG=
VHHH 110430Z 34013KT 9999 FEW025 17/10 Q1021 NOSIG=
VHHH 110400Z 34011KT 9999 FEW022 18/10 Q1021 NOSIG=
VHHH 110330Z 34012KT 9999 FEW022 17/11 Q1022 NOSIG=
VHHH 110300Z 34013KT 9999 FEW022 16/11 Q1022 NOSIG=


You may get wind shear going in/out of a strong jetstream.
There may be wind shear near thunderstorms.
Wind shear is the sudden change in speed/direction of wind.

The results of the FDR/CVR may prove me wrong as is often the case.
On the surface I don't see any evidence of windshear.

24left

Thanks so much for explaining this. Very cool.

YVRtoYYZ

Bit late to this thread. Winds at 330 mean that the winds are coming off the water (NW direction). There is no terrain that would cause mechanical/terrain-induced shear or turbulence. Given the met conditions, I don't see weather as being an issue per say. Instead, we have a runway configuration (07R) favouring tailwind operations. I was in the TG lounge watching ops on 07R 15:00 HK time onward on Dec 11, noticed the windsock direction and wondered why they weren't using 25L instead.

My gut feel is the aircraft carried too much speed on approach resulting from a quartering tailwind, flared too aggressively to bleed off the speed, encountered wake turbulence and struck the tail. Wake turbulence is always a possibility given that they were launching heavies one after the other (typical HKG).

Edit: I should note that the 07s are favoured runway ops in HKG due to traffic sequencing and terrain. The 25s take the flight into Macao (VMMC) approach profiles and becomes a nightmare for VHHK ACC to sequence and separate. Also, the heavies (especially B747Fs) have a poor climb profile and making the mandatory left turn at PRAWN at 5000ft to avoid VMMC airspace and terrain difficult.

24left

@YVRtoYYZ
Thanks so much for this post. Fascinating.

CZAMFlyer

No worries on the late arrival. At the risk of being the type of person who directs others to posts in which I've already stated something, I'll do exactly that. In post 3668 above, I commented on the photo taken just before landing and said the weather and sea state look benign with no visual indication of wind shear. My (edited soon after) remark also questions the likelihood of mechanical turbulence.

I wouldn't be surprised if this bears out to be true; it seems more plausible.

WaytoomuchEurope

This thread is fascinating to me. I can BS my way through any (business) presentation and I get paid to pretend to have some intelligence, but some of you folk in here have actual intelligence.

It's all Greek to me, but fascinating all the same.

sweden05

FlyerTalker70

737MAX?! Yikes, I'm on that bird to EDI from SWF on Jan 1!

Here's to hoping AC swaps this with a 763 with pods that don't deflate

-James