S-92 Loss of control event - report
 

Just seen this. Not read it yet but saw a summary elsewhere. Looks interesting! https://www.nsia.no/Aviation/Published-reports/2024-03?pid=SHT-Report-ReportFile&attach=1

"The internal investigation team also wanted to listen to the cockpit voice recorder in order to better understand what had happened. In accordance with internal procedures, they asked for the pilots’ consent to do so. The pilots did not consent to this"

It appears a simple pre-departure brief between the crew would have avoided this whole incident, this is standard offshore procedure.

https://www.nsia.no/Aviation/Published-reports/2024-03

That pilot's refusal is typical of a culture prevalent in Norway where self belief and entitlement triumph over what is required. We hear more and more a unionised culture of doing as little as possible and scraping through proficiency checks in the simulator in Stavanger but due to union rules nothing can ever be done. A pure hierarchy based on time served. You don't have to be that capable, just get by on the day then sit back and collect the pay cheque until retirement. If only we had it that simple, now we aren't EASA so no more crossover. Just see it in passing across the median.

I wonder how much or little awareness Equinor and other oil companies have of the situation?

I've just read it and found it be 59 pages of very little real analysis or new facts, and a lot of ambiguity and contradiction. At one point the wind is said to be 42 kts, and another it was 33 kts. At one point the aircraft accelerated to 28 kts and another it is 35 kts - neither of which tally with the wind speeds. Then we start talking about Somatogravic illusion - really? This illusion requires a significant acceleration, and was first discovered during the early jet age in the late 1940s. By definition, a helicopter taking off into a 33 kts wind and accelerating to 35 kts is not in this regime! Actually, I don't think I have ever encountered truly rapid acceleration in a helicopter with the exception being when pointing very nose down (up to 90 degrees). However, the acceleration is mainly due to gravity and so you do not encounter the 'push in the back' required for SGI (and obviously done in good visual conditions - but the physics is the same).

Cyclic force trim release function - talk about groundhog day! Are we really having to discuss how to use the FTR in 2024? Almost a minute of no intervention or assistance by the captain? I know we can all be 'armchair critics' (or Monday morning quarterbacks), but I cannot get my head around this. The captain was an ex-military instructor, although that is almost irrelevant as any captain should intervene within a few seconds of a situation like this developing.

As for 'blowback' - give me a break! At least VRS was never mentioned at any point......

I find this extremely damming on many levels, and cannot fathom what kind of personal safety culture would lead to this decision. My own view would be to have as much information as possible in the report, to help prevent some other poor crew having the same - or worse! - happen to them, or even it happen again to the same crew. I know from my own experience, that the recollection of what was said and not said during an incident, are often not what the CVR reveals!

Disappointing on so many levels.

Let us be thankful for small blessings.
(Also: nice post).

Somotogravic Illusions can and will occur throughout all pilots' aviation careers when flight operations include instrument flight conditions, low vis operations and/or night flying.

The basic reason for this is that the human vestibular and other balance system sensors are not naturally trained for flight accelerations (we are not birds!).

Somogravic illusions can can result from gentle (and therefore imperceptible), medium or rapid accelerations, or attitude change in any of the 3 axis.

The vestibular sense organ is UNABLE to resolve the difference between an acceleration or attitude change without the input from some other sense organ.

Slow bank angle change, for example (less than about one degree per second), cannot even be perceived the vestibular system.

I thought that this reference and associated included references was interesting:

https://skybrary.aero/helicopter-som...usions-skyclip

And the Wiki coverage is comprehensive:
https://en.wikipedia.org/wiki/Sensor...ns_in_aviation

I believe you are mixing Somatagravic with Somatogyral. They are different, and the former is caused by linear acceleration in the longitudinal axis (can also be a deceleration). I have certainly encountered the latter - typically called ‘the leans’

Yes, 212man you are correct. I've didn't know that the two illusions of acceleration and movement came from two different parts of the vestibular organs (the two otoliths and the semi-circular canals).

As you said, the first is described as Somatogravic and the second Somatogyral. In my years of aviation I have never discriminated between the two!

In the absence of strong visual and other sensory inputs both sensors of the vestibular organs may be involved in false orientation/spatial awareness.

As I understand it, the somatogravic illusion ( the feeling of pitching nose up when experiencing a liner acceleration forward) was well documented by carrier pilots being steam launched and why they used to do the launch 'hands-off' to prevent them pushing nose down into the sea.

They would certainly experience it in night or DVE conditions, not so much with a good horizon, as the visual imagery will be given precedent by the brain I think. I think the early military jets (Canberra etc) were prone to it doing missed approaches in IMC, until it was better understood, but that's from memory.

212: showing my age….but, does the commercial pilot community teach helicopter instrument take-offs? Or for that matter, does the military?

It's not part of the UK CAA CPL or IR, but it is definitely part of any offshore line training/type rating training/LPC/OPC Sim training. This is bread and butter stuff for an offshore operation.

If the PF had ever been taught IFTOs it certainly wasn't apparent from this incident - 25 degrees nose up!!!

The transition from visual hover to instrument scan needs to be instant - ask anyone who has done night deck departures from a warship when you start around 50' or less above the water.

The PF clearly wasn't looking at the AI during the departure - select and hold an accelerative attitude, how difficult is that?

If they want to avoid this type of incident then give the crews NVG - no more flying into black holes, especially not with a 900' cloudbase and 7000m vis, they would have had a visible horizon on goggles, especially since the lights of the rig were all behind them.

I agree the sections on somatogravic illusions and blowback are just padding and wholly irrelevant to the accident. The 'pitch up' they refer to regarding blowback (flapback) happens at the onset of ETL, not at 40 kts and a gentle hover taxi forward will not feel like a pitch up either.

Neither pilot was doing their job very well that night and I am amazed they managed to avoid the water.

we have been here before:

https://www.gov.uk/aaib-reports/aaib...d-aw139-g-lbal

https://wvmetronews.com/wp-content/u...nal-report.pdf

Why bother to install a CVR if it can only be referenced in an incident where both crew are deceased?

I was investigating a ditching incident where I suspected there was a systemic problem and so wanted to review the CVR for the crew's last 4 landings. Nope, that's not allowed.

There must have been some fantastic history of abuse in Europe for the unions to have their backs up on this.

Not an offshore type so please excuse my ignorance. What’s Vmini for this type? Surely on a pitch black night rolling off the side of a deck over water it’s effectively IMC whilst below Vmini? Are AFCS functions used to mitigate such departures?

Minimum coupling speed for the IAS is 55knts.

​​​​​ATT (long term attitude hold) is available as the basic flight mode without trim release depressed. It is good but slow to react (like the whole machine) through the trim controls.

I've done a handful of blackhole landings and departures on decks and moving decks, not many but it's a challenge.

As the PM you need to be on top of your game.

Vmini is 50 KIAS. Your point is valid and has been the topic of conversations before. However, bear in mind that from a certification standpoint Vmini is considered for steady state flight. During an offshore take off, using a positive accelerative attitude (we always used -10 absolute, not delta) you will reach and pass 50 kts rapidly. Even more so with 33 kts of wind!

The correct sequence should be - establish the stable hover with FTR depressed, then release when established. Pull pitch to climb vertically, depress FTR passing TDP to set the accelerative attitude, then release and monitor the acceleration and no sink. Company SOPs might then include using GA mode passing 55 KIAS, to establish a Vy climb at 750 ft/min. In turbulent conditions it may be necessary to make minor cyclic inputs in the initial climb, but at night I’d suggest doing that against the force, and not use the FTR.

In some types (eg EC155) you would not need to use the Force Trim Release at all. It has "follow up trim", making such departures very easy.

Exactly, and the inbuilt transition from 'follow up trim' to 'cruise mode' actually raises the nose, and sets an attitude that should achieve Vy. In my response I was trying to keep it S-92 based, and address the questions about Vmini.