Odd optical effect at altitude

[Hokulea]

Dear all,

Please forgive this intrusion from a non-pilot; I am a professional astronomer who works on a large 14,000 ft mountain in the Pacific and would like to ask a question about an optical effect I and some other colleagues have observed.

While working at the summit one evening I noticed a moving light to the east just below the horizon. I watched it for a while and although it was generally heading in a northerly direction, I noticed it was moving in an extremely unpredictable manner, sometimes vertically, sometimes even apparently reversing course. All these movements would last for a few seconds and were of the order 1 to 5 degrees.

I checked the flight schedules for the local inter-island airlines and this coincided with a regularly scheduled flight climbing to its cruise altitude but still below my own altitude. I'm fairly confident this was an airliner rather than a military jet and that I was seeing some optical effect probably caused by air turbulence. Incidentally, the distance to the aircraft would be between about 40 to 60 miles if it was flying the normal route.

I am very familiar with the effects of atmospheric turbulence on objects above the horizon (in fact it's part of my job) and have not seen anything like this before. I have, however, now noticed this same effect several times at the same location on aircraft which are below or very close to my horizon.

Before I take this from idle curiosity to thinking about researching the phenomenon a little more objectively, I thought I might ask others that work at altitude (such as the pilot community) whether you have also seen a similar thing? I have been unable to find any literature describing this effect, although I haven't done a full search yet, but it may well be a commonplace observation made by pilots that I'm simply not aware of. This, of course, may also be a physiological effect caused by altitude (we do not use supplementary oxygen) or a simple optical illusion due to having few if any visual references, so any observations by pilots, whether positive or negative, would be very helpful.

If anyone wishes to check my credentials (and to make sure I'm not just an oxygen-deprived loon or some UFO nut!) please feel free to PM me, I will provide details on request and why this may turn out to be a useful research project. Many thanks in advance and if you have questions I will of course respond as quickly as I can.

[PaperTiger]

Terrestrial refraction ?
http://mintaka.sdsu.edu/GF/explain/atmos_refr/terrestrial.html

[BOAC]

There is a well-known phenomonen where when looking at a single light source in an otherwise fairly empty visual field, the light 'apppears' to jump around. I think it is called 'autokinetic motion'. Try a 'Google' on it - it has been the cause of many UFO reports in its time......of course, that doesn't mean...........................:eek:

[easy307]

Cylinder of O2 at 14000ft.

And cut back on the shandy.

[Bullethead]

G'day Rainboe,

What you've just described is called autokinesis,

http://en.wikipedia.org/wiki/Autokinesis

and it occurs when there are no other objects visible.

I don't think that our friend Hokulea is experiencing this as his object appears below the horizon, which must be visible or how would he know this.

Regards,
BH.

[Hokulea]

All,

I appreciate all the replies so far, they have been very helpful, and apologies for any thread drift I introduce below:

PaperTiger: thanks for the link on terrestrial refraction. As you might expect I'm more than familiar with astronomical refraction but woefully behind on the mechanisms behind terrestrial refraction. I did actually wonder if this was some effect similar to a mirage so will follow this up if the effect turns out to be real rather than physiological.

BOAC (+ Rainboe & BH): never heard of "autokinetic motion" or "autokinesis" and am sure no one I work with has either. Thanks for the pointer, I think this is the likely explanation.

Easy: believe it or not, the current rules don't allow me to take a swig of O2 at the summit! If I do I'm considered too ill to remain at 14,000 ft and will be summarily transported down to where an O2 cylinder isn't needed. Oh, and shandy is prohibited at the summit for anyone who works there...

Rainboe: I can confirm that a blast of oxygen at 14,000ft has an absolutely stunning effect, wish we were allowed to do it these days. You don't even need to have problems with the altitude, the additional oxygen has a spectacular effect even if you're fully acclimatized. It's one thing that disappoints visitors to the summit, the sky doesn't look that great even on dark and clear nights, but go down to the residence and visitor centre at 9000 ft and the sky is, frankly, mind-blowing. Even with a whole lot more atmosphere above you.

BH: thanks for the autokinesis link, that's a great starting point. As for not being able to see the horizon, your assumption is correct. I do, however, have 11 years experience of the summit and even on the dark nights can make out some of the other observatory structures if I'm dark-adapted, so know where the horizon is, at least to a few degrees. They are not in my line of sight though when I see the aircraft (from where I usually go out to check the weather that is) and so then have few if any visual clues, but do have a good idea where the horizon ought to be. As for the wikipedia article, it says a stationary light. A quick back of the fag packet calculation suggests I see the aircraft move at around 4-5 degrees per minute on average (neglecting the random motion), so that's quite slow and imagine it might be as good as a stationary light.

I've persuaded a photographer friend/colleague to help me determine whether reality matches perception in this case although that won't happen for a month or two. In the meantime, thanks again for your help, and if any of you lot are fortunate to visit the Big Island, I'm sure I can organize a free tour of the summit as a thank you.

[john_tullamarine]

... I am staggered that a bloke who needs good vision .... is prevented from using supplemental oxygen to brighten up the visual field.

Any pilot who has had a chamber run or even a 100% suck on the mask at top of descent during night operations knows what I am talking about .... all of a sudden you can see a million things which previously were invisible ...

Maybe you need to get the top man into a chamber so he/she gets to see what you folk are missing out on ...

[Hokulea]

John,

It's a bit of a misconception that astronomers need good vision, at least these days. It's definitely a very helpful thing but these days just about all astronomical research and observing is done via a computer, and some of it is completely automated. Sometimes you don't even need an astronomer there to make sure it all makes sense although you wish you did when you look at the data 6 months later...

The O2 thing is one of these silly rules that the bureaucrats love, it lessens the chance of a lawsuit but makes life more miserable for everyone else, or at least there's less fun...

[Rainboe]

Can you explain why you're not allowed to take a blast of O2? Sounds strange. I'd be out there doing it all the time!

Can I ask you a few questions about the place? I gather all you have up there is a duty astronomer and a few maintenance people. Is it rather boring? And night shifts only! You have a base down at the coast to chill out? How far is the drive to get up there, and is it precarious? I've been up the Eiger in Switzerland and was amazed at how short of breath I was at 10,500', so how does 14,000' hit you? Any other effects? Bad sleep (gasping for breath), dreams, appetite, taste etc.?

[perkin]

Rainboe - if you give it a bit of time (maybe up to a week for Europeean mountain ranges (Caucasus excepted) depending on your basic fitness and physiology) you'll acclimatise properly and will then experience little or no adverse effects on your breathing. It took me a night sleeping at about 10000ft until I got to this stage - presumably my body was able to adapt to the reduced oxygen whilst in a resting state. Suffered before this, then after a night up high I was skipping about at up to 14000ft like a mountain gaot! Its actually a deeply unpleasant experience venturing down into the lower valleys after you've spent a long time at high altitude - it feels like you're suffocating in the dense humid air!

[Rainboe]

'Tis this bit I didn't understand the reason for:
Easy: believe it or not, the current rules don't allow me to take a swig of O2 at the summit! If I do I'm considered too ill to remain at 14,000 ft and will be summarily transported down to where an O2 cylinder isn't needed. Oh, and shandy is prohibited at the summit for anyone who works there...

I see about the shandy- it does that to me down at sea level, but the O2.......

[perkin]

Ahhh, I think in this particular instance its essentially meaning that by needing a shot of oxygen, that is evidence that someone is suffering from acute mountain sickness (which could result in pulmonary or cerebral oedema, frequently fatal if untreated by oxygen and immediate descent) and must therefore descend immediately...Presumably they don't supply recreational oxygen!! Its possible that by driving up from sea level to 14000ft someone could develop AMS as a quick drive doesnt allow sufficient time for the body to acclimatise, hence the emergency supplies of oxygen at the summit.

I guess its the same as your emergency O2 supply on the flight deck - if you used it, it would indicate some sort of problem to warrant doing so...the result is in effect the same thing - you'd descend to a safe altitude...

[Rainboe]

Some have been known to use it after a heavy night. What does Hokulea say?

[Hokulea]

Perkin has it pretty much spot on, both on the effects of being at altitude and why we're not allowed supplementary O2 unless there's a medical emergency, and at that point we're rushing them down to lower altitude/hospital anyway. In addition, we've been told that taking supplementary O2 could possibly mask the symptoms of acute mountain sickness, namely shortness of breath and shallow breathing at rest (more specifically, both symptoms of high altitude pulmonary edema, HAPE - you don't want to get that, I can assure you!). It's rare, but on a couple of occasions I have had to take people straight from the summit to hospital at sea level, and I'll admit it's a frightening experience, for both the victim and the helper. Unfortunately we can't lose altitude as quickly as you guys!

On the other hand there is a study that shows supplementary O2 at altitude is beneficial (I can dig out the reference if you're interested), but I do have to go by our SOPs or I get a little more than a smack on the wrist.

Rainboe, as to your questions in #10, and at the risk of some further thread drift (sorry!), there are a dozen observatories at the summit and they all operate a little differently. In general though, at night you have a telescope operator and an astronomer or two who are either visitors or staff (or both). During the day the technical crews will be up for a variety of reasons.

The shifts can be long, up to 13 hrs, and yes, it can be boring. It's approx a 30 min drive from the residence at 9000ft and we can't stay more than 14 hrs above that altitude in any 24 hr period. Half the road between the residence and the summit is unpaved and steep and is certainly treacherous. There have been several fatalities over the years, mostly tourists, but I've seen some rather nasty accidents involving observatory vehicles as well.

As for staying at altitude, we acclimatize at 9000 ft the night before but the first night at the summit is always unpleasant although usually it's just tiredness. It gets better quickly though. Personally, I have trouble sleeping at 9000 ft and yes, I get some rather vivid dreams! I get the very occasional mild headache, but that's invariably because I've forgotten to stay hydrated, and get breathless only when I've forgotten where I am and ran up the stairs! Oh, and something that gets everyone without exception - you become stupid - but fortunately no one sees the difference with me...

We have a base at sea level and in fact spend most of the time there. It's about a 50 minute drive from there to the residence on paved roads.

I've mentioned a lot of the bad things about the job, the good things outnumber them significantly so don't get the wrong impression. The sunsets and sunrises are something else (although I'm sure you guys get just as good views of them), the shadow of the mountain at sunrise is particularly awesome, and making discoveries most nights, or helping people make them, is a feeling that's hard to describe!

[Hokulea]

All,

Apologies for re-opening an old thread but thought those that contributed might be interested in the result of a simple experiment we did recently.

A colleague and myself took an old non-digital SLR camera to the summit and took some long-exposure photos on a dark moonless evening when a local inter-island flight was due to appear. Neither of us could see a clear horizon but we both saw the aircraft's beacon, roughly when it was expected. Both of us agreed that the flashing light was doing some "weird" things to the naked eye although we didn't agree in which direction the light appeared to deviate - big clue.

I've just got the developed pictures back and the relevant one shows that the beacon's path is rather straight. Actually, it's slightly curved, I can't put a straight line through the path, but there are no large deviations that both of us were convinced we saw with the naked eye.

Therefore, I think that what I and others have experienced is autokinesis or something very similar. Whatever it is, it does seem to be a physiological effect.

I would like to thank all of you for pointing me in the right direction for something that has bothered me for some time! I am very grateful.