oculogravic and somatogravic illusions

[sarabande]

an AAIB report indicates how your body and eyes can be deceived as to the real horizon.


More flighty than boaty, but there are some interesting comments relating to the effects of gravity and acceleration/deceleration forces on the human brain - perhaps relevant to seasickness or those other occasions when the boat appears to be tilting when you know it cannot possibly be so, or the way the land moves when you come ashore after a couple of days.


http://www.aaib.gov.uk/cms_resources.cfm?file=/1-2011 G-REDU Appendices.pdf

The details are in Appendices A and B

 

[AntarcticPilot]

an AAIB report indicates how your body and eyes can be deceived as to the real horizon.


More flighty than boaty, but there are some interesting comments relating to the effects of gravity and acceleration/deceleration forces on the human brain - perhaps relevant to seasickness or those other occasions when the boat appears to be tilting when you know it cannot possibly be so, or the way the land moves when you come ashore after a couple of days.


http://www.aaib.gov.uk/cms_resources.cfm?file=/1-2011 G-REDU Appendices.pdf

The details are in Appendices A and B

Makes sense. I am sure we have all felt a bit strange when the train next to us in a railway station has pulled off, and we think we're moving - but there are no acceleration forces! Perceptions from different systems mis-match, so we feel momentarily disoriented.

I have had an occasion when I got a similar feeling in a sailing context, but I'm not sure of the detailed causes!

I had sailed out of Rhu, first day on a charter, and fairly out of practise; at that time I hadn't sailed for several years. This was at a period when I was not sailing regularly, but just occasionally chartering. The geography of the Clyde region was familar to me; it was the favoured stamping ground of my family when I was a boy.

On exiting the Gare Loch, I got completely disoriented regarding the relationship between what I was seeing and the chart. This is unusual for me; I have a strong sense of direction, and maps and charts have been my profession for years. I was OK until I realized that Loch Long (our destination) wasn't where I thought it was! But when I realized the mis-match between my internal orientation and the external one, I felt very odd for a few minutes, simiular to the railway station illusion.

It has never happened since, but just once was enough.

 

[KellysEye]

Certainly pilots can get disoriented if there isn't a horizon and they are too busy to look at the artificial horizon. I saw the Neil Williams, the Eurpoean aerobatics champion, crash at Biggin Hill because of that. And I remember Jane and I staggering along the dock, trying to balance, after long passages.

However Appendix B says: 'By I-20s the descent rate was 980ft/min and this descent continued until the point of impact, the rate increasing gradually to 1380ft/min at impact'. I being the time in seconds before impact.

Incredible.

 

[Halo]

I get these .... usually after the second bottle of red.

 

[skyflyer]

I saw the Neil Williams, the Eurpoean aerobatics champion, crash at Biggin Hill because of that

???

The aircraft lower wing spar attachment bolt failed and the wing started to fold upwards. Williams, realising what had happened, rolled inverted so that the stress was taken instead by the upper attachment bolt (now lower, because of being inverted), so locking the wing in place.

He then flew an inverted circuit to land, rolling upright at the last moment.

A truly inspired piece of flying

story here

 

[Plevier]

???

The aircraft lower wing spar attachment bolt failed and the wing started to fold upwards. Williams, realising what had happened, rolled inverted so that the stress was taken instead by the upper attachment bolt (now lower, because of being inverted), so locking the wing in place.

He then flew an inverted circuit to land, rolling upright at the last moment.

A truly inspired piece of flying

story here

Inspired flying indeed but that was at Hullavington not Biggin Hill.
Williams did crash at Biggin Hill but in a Stampe. I don't know the cause.
Commentator John Blake who died recently said "He's taken it behind the hangar... and left it there!"

 

[skyflyer]

haha, thanks for the correction - I had blurred the two incidents in my mind. I stand corrected (again )