734 hard landing @ Exeter
 

Happened this morning

https://cimg8.ibsrv.net/gimg/pprune....6a239a527.jpeg

That looks nasty !
I'd guess given the age of the aircraft it could well be written off.
At least it wasn't one of their new shiny -800s !

More photos on AvHerald:
Accident: West Atlantic B734 at Exeter on Jan 19th 2021, hard touchdown

A photo of the airframe post the accident here shows that the structure is no longer equally supported by the undercarriage. The cargo is still aboard as it is currently too dangerous to remove it.
https://samchui.com/2021/01/19/west-...a#.YAdUty3fWfB

At first glance, the photos appear to show that the LH inboard flap has dropped.

But look closer and it can be seen that it's not the flap that has moved, but the upper surface of the wing root that has been pushed up by the MLG trunnion trying to break through.

The fuselage damage on the port side looks as though it has been caused by the leg or its support structure breaking through the upper surface of the wing.

I am curios to know how many Gs are we talking about here

Would be interesting...Hard landing checks are carried out for any landing above (I think) 2,1 Gs, but a technician once mentioned to me that even a 3-4G landing (!) probably wouldn't cause major damage on the 737, longer versions being more critical than shorter ones. Would also be interesting as to what happened - weather doesn't look to bad / gusty... [EGTE 190220Z 23010KT 9000 -RA SCT012 BKN040 12/10 Q1009=] - source avherald.

We're a few miles south-west of Exeter and I can remember hearing the wind hitting the house during Monday night/Tuesday morning so 10 knots seems like a surprisingly low forecast. Looking at FR24 the ground speed on approach was varying fairly rapidly between 111 and 133 knots, so I'm guessing they were dealing with some reasonable gusts. Data also shows a VS of -1,024 FPM over the threshold, but the aircraft was apparently still airborne as it reached the intersection with the old RWY13/31.

That's a nasty thing to happen to anybody. Hope the crew are OK.

TGZ let us assume that the FR24 data does not give an accurate touch down point. I do not know if it does or not. But if it was accurate and they were still airborne at the intersection of the old RW31 then that was not the place to be in a 737. Let us see what more data provides...

Good point. I'm not familiar enough with either the inner workings of ADS-B or what internal processing FR24 do to their data to speculate on how accurate it might be. Thankfully whatever happened there was a safe outcome for the crew, if not the airframe.

Had to take the car to the garage this morning and could see CY on the apron as we drove past the airport - I swear the aircraft is actually tilting several degrees to the left.

It doesn't.

On closer examination of the data, that seems unlikely. Height over the piano keys (after adjusting for QNH and elevation) was about 40' AAL. There are two subsequent plot points after that, approaching the cross runway, but those indicate 100 feet lower, which is clearly impossible.

It wouldn't be altogether surprising if hitting the runway with enough force to drive the gear up through the wing had also done strange things to the Mode S air/ground logic.

Human factors, rather than bad weather, is my theory as to the main cause of this accident. The Circadian Rhythm at 02:00 in most humans demands deepest sleep, with lowest body temperature occurring at 04:30. This accident occurred close to the lowest point in the average person’s alertness cycle.

Nightstop, is this also valid when flying regularly on nights (as many of these crews do)? This is not a challenge but just a question.

Pistonprop:

This safety issue has been highlighted ad infinitum. Here is a FSF article on the subject. I’ve no connection with this Company or anyone involved whatsoever.

https://flightsafety.org/hf/hf_mar_apr99.pdf

This happened on the first night of what would be 5 nights of duty.
First night into the WOCL is the toughest. Incredibly difficult to rest for, weekend off with all the normal home triggers to get you up and going. And if you’ve got kids they’re not even at school at the moment if you’re trying to rest on a Monday. So I’d say human factors would be a very relevant area of mitigation.

I think it very much depends on the individual. To me, if properly rested previously (i.e. having had enough sleep during normal patterns), the first night is alright. But the second and third nights for me hurt more until the body clock at least adapts slightly.

The pics on AvHerald clearly show the aircraft is listing left, mainly due to the fact that the port main undercarriage has been pushed-up through the wing.

Local reports that the airframe is bent to the point that the ULD's could not be pushed off.

Other reports indicate that loaders were not allowed to board the aircraft with one of the main gears in an unstable state, for obvious reasons.

Not a good thing for West Atlantic loosing this hull after transferring so many aircraft to the spanish registry.

Along with being one of the very few cargo airlines to make pilots redundant late last year citing “Brexit “ ...

FDR traces from today's Final Report:

https://cimg9.ibsrv.net/gimg/pprune....1138d13a68.jpg

The report states the touchdown G was 3.5 which seems quite low for the damage that was caused.

From the report: "The maximum vertical acceleration recorded by the FDR on touchdown was 3.8g, at this point there was 3° of left roll. However, FDR sample rates and sensor locations are not ideally placed to determine peak forces on touch down."

The fact that the touchdown was sufficiently hard to deform the LH MLG beam would appear to support this.

I have read the report but a lot of other aeroplanes have touched down with a greater G with less damage.The report is a bit vague, perhaps the fdr data was poor, but it does mention a vertical rate in fpm on the wing box that exceeded the design tolerance Surely Boeing must have been able to work this into a G .It seems strange that it was not included. Reading the report it didn’t seem as factual or as well written as what we have come to expect from the AAIB and I have read a lot of them.

Thanks Dave for the info from the report. That was a fairly steady rate of shear throughout at a mild rate. Aircraft performance follows the attitude the pilots have placed the plane at... There is no obvious vertical flow occurring from a quick comparison of speed/attitude and derived VS. Crew would like to have those 30 seconds over again I guess. The cognitive load on a turbulent approach can get quite high, which is why the rules on stable conditions and the response to GPWS alerts is such an important input to the safe outcome of a busy little approach. A "pull up" in the flare is pretty much a good suggestion to the drivers. The 3.5 slope kind of sucks, that is going to always need a good stable finals to remain within reasonable limits for a heavy landing wieght, <900FPM or more for the stable slope....

stuff happens

p3:
"The commander recalled that as the aircraft crossed the threshold, at about 100 ft, the PF retarded the throttles, pitched the aircraft nose down, from about 5° nose up to 4° nose down, and then applied some power in the last few feet. During these final moments before the landing, there was another “SINK RATE” alert. The result was a hard landing. A “PULL UP” warning was also triggered by the GPWS, but it was not audible on the CVR."

Golly. Did he catch the #1 wire on the tailhook?

p9:
"There was no stated requirement in the OM for both pilots to monitor that the stable approach criteria were maintained below 500 ft, with the aim of delivering the aircraft to the point in space above the runway from which a flare manoeuvre will result in touchdown at the right speed and attitude, and within the touchdown zone. This is something other operators are known to have in their OM, with a requirement to conduct a GA if the stable approach criteria are not maintained to the landing".

An amendment to the FOM coming soon?

The OEM's FCTM for every type they make states a need to maintain stable flight path for the rest of the approach, an item that the report does note as well. If we are stable at 500' and inverted at 200' it is hard to justify the approach as being "stable" and consistent with the desired outcome of being able to reuse the plane and crew without rework or scrapping.

p16:
"The commander also stated that he felt it was too late for him to take control or call “go around” from about 100 ft RA."
That is pretty sad to see in writing coming from an experienced crew. Is there a magical figure where the plane suddenly doesn't do what it is supposed to? To save tire wear, we would routinely do a G/A at the start of a flare, in the flare (and at any point up to the selection of TRs) Years ago, the wisemen comment to the new 747 drivers is when all else fails, go wings level, 5 degrees nose up and all thrust that you can get... it may not be pretty but it is hard to hurt the plane in that condition, and it works for every Boeing other than maybe the 717 and 727. If we believe there is a latest point that we can do a go-around, then that needs to be dispelled. Presumably, the alternative is that at 100-RA we just give up as the outcome is preordained?

Is there a statement in their OM for both pilots not to crash? Or to keep their eyes open during landing? Or to keep breathing continuously? FML

Fascinating that an 18-page report contains no explanation of why the co-pilot could not land the aircraft. This was the ‘cause’ of the accident (AAIB purpose: ‘…to improve aviation safety by determining the circumstances and causes of air accidents and serious incidents, and promoting action to prevent reoccurrence’) and deserved exploration.

Especially from (4), I'd say, the pitch input is lagging behind what is needed to get a stable descent rate. Not completely anti-cyclic, but the corrections are sufficiently delayed and being too big, making it impossible to dampen the inherent GS deviations. Which in turn suggests a lagging brain, which in turn might suggest fatigue.

A Go-Around and next landing may have suffered from the same problem, fatigue doesn't go away.

That's a tad unfair on the AAIB. While it doesn't specifically use what the NTSB terms "probable cause" and "contributory factors", the section in the report labelled "Conclusions" is pretty unambiguous:

Without the ability to get inside the heads of the crew, what more would you like to have seen?

It is a nasty little technique.... it has remained around from the MD80 and B727 which could benefit from an initial flare and then a slight de-flare. The risks on the method are enormous, Doing an analysis of what the wheels sink rate does in a de-flare gives zero comfort as a procedure to avoid a hard landing. forward stick may help a P51 or T6 wheel landing to plant the gear, but otherwise is high risk.

Dave, some exploration at least as to why an experienced but possibly borderline-competent pilot was not able to land an aircraft. Fatigue? Insufficient cues? Distraction? Fundamentally unsound technique? There’s simply no effort to explain it. The AAIB costs somewhere around £8M a year, and really should be doing a lot better than that.

Text book example of why you should go around when an approach becomes unstable. Interesting how many hours the co-pilot had; 19,000 with 5,000 on the 737. The captain had 15,000 with 9,000 on the aircraft. I also wonder why the co-pilot did both landings, particularly in somewhat challenging conditions at an airfield the company later designated captain‘s only for landing. The captain had only flown 25 hours in the last 3 months so presumably could have used the practice. Middle of the night, Covid impact on currency, company disruption potentially also distracting the crew, made for a number of holes in the Swiss cheese.

Looking at the experience levels I wonder if these were two Captains flying together perhaps, although not mentioned in the report. Seems strange that a pilot with that experience and time in the company would still be an f/o, when you consider that 3000 to 4000 hrs is a typical experience for 737 Captains at some low cost carriers.

In my airline you get two shots at command and then you’re out of the process. Having many hours doesn’t automatically mean you are suitable to be a captain. If anything, having such high hours as an FO often tells a story in itself.

Perhaps the report in question goes a long way to explaining that. . . . . .

The bulk of the FO’s hours were most likely obtained elsewhere - accumulating those kinds of hours at an operator like WA is impossible. The norm I believe was 1 week on/1 week off with no more than 2-3 sectors a night.

For me, the report did not really drill into the underlying reasons for the accident. Given that this report was 18 months in the making, I thought that it would be very detailed. The NTSB reports like to track the history of the pilots in their earlier career, through their recruitment into the airline and their detailed training history within the airline. Failed checks and commands etc are fair game.

My own unfortunate experience is that airlines have a dirty little secret of a group of poor pilots. How big this group is depends on sound recruitment, training and a plan of how to deal with those who are not able to meet standards. The slightly steep, Exeter, approach should not be a very challenging one, especially for a 19000 hour pilot. I'd bet that these pilots had a long history of poor performance dating over many years and various airlines. How they were recruited and why the airline did not act over the FO remains a mystery. What can we learn from such a mystery?