The widely believed story about red being the best colour for reading charts is true only at very low light levels. Above that you may as well use white.
Interesting but made irrelevant by the amount of light G1000 / Avidyne type instruments put out.
I stopped using red light in the airplane cockpit a long time ago. Red light makes it so difficult to read anything that you focus inordinate amount of your attention to a task that should be trivial, i.e. reading a chart. You introduce fatigue and is source of error especially for VFR charts that contain colors that are plain invisible in red light.
When I used to be into night cycling, I used to simply close one eye whenever I could see a car was on the way, to preserve the night vision in that eye.
The first person I’m aware of to try and ‘debunk’ the ‘red is best myth’ was an amateur astronomer who plainly didn’t understand basic physiology/physics. At the time it seemed to be gaining a lot of traction amongst astronomers, but searching for the original posts on google groups, I can’t find them any more and I get the impression his arguments have lost support. I’m not sure who wrote this article, but I don’t find it entirely convincing either.
If I understand this article correctly the line of argument goes:
1) red light at high levels is bad because it still stimulates the rods that enable night vision
2) red light at low levels causes incongruent rod and cone signals which are confusing to the visual system
3) maximally rod-stimulating light at a level high enough to stimulate the cones, is actually better because it stimulates causes cones and rods to provide a congruent visual input and it is comfortable at a level low enough that you can use it without destroying your night vision.
The problem here, it seems to me, is that I don’t see how a red light will stimulate the rod cells and cause them to lose dark adaptation, without also causing them to send a signal that is roughly congruent with the cone signal, albeit at a lower level.
That said, the retina is horrendously complicated with a lot of individual variability – e.g. in forms of colour vision, and also in the ratio of red:green (L:M) cones and if there were good evidence that some colour other than red actually worked better the onus would be on us to work out why that was. But as far as I’m aware, all the experiments done thus far have supported the idea that red is best. Given that this is something the military have a strong interest in, I would suspect that it will have been researched pretty thoroughly and that not all the research will be in the public domain.
made irrelevant by the amount of light G1000 / Avidyne type instruments put out.
Can’t they be sufficiently dimmed?
Interesting argument, KWLF. I don’t know enough to say anything.
One does often wonder along the lines of “I would suspect that it will have been researched pretty thoroughly” but sometimes one can get a surprise when one discovers something which really looks like it had not been researched, or if it was, the stuff is not easily found. Google especially is pretty good at losing stuff older than about 10 years. Usenet posts are retained better in some of the www sites which used to leech from usenet, than in google’s own “Groups” database which nowadays they try to prevent people discovering too easily (it rarely features in hits despite it’s vast size). In my previous business, 1978-1991, I designed something like 100 products and almost none of them google…
Sorry for the duplicate post… The first one didn’t seem to appear, so I more or less rewrote it.
I agree with you that not everything has been thoroughly researched. When I was in university with access to lots of journals I did do a literature survey – I had the notion of making an LED torch that would preserve night vision relatively well, yet still give you a degree of colour vision for reading ordinance survey maps. I did chat to a pilot at a party about adapting it for aviation charts too. I had some degree of success but my PhD thesis got in the way. By the time I’d finished it, tablets and GPSes with ‘night-modes’ were clearly going to take over, and it seemed like a good idea that arrived too late.
There certainly have been studies looking at this and many of them are available in the public domain. However a lot of them were relatively old and I would have had to send away for them. There were also a few references to military studies that I don’t think I could have accessed.
Where I could imagine there being an issue, though, is that until a decade ago it was quite acceptable to perform a study of this nature on 3-4 people on the assumption that what was true for one person would be true for everybody. It’s often a fairly good assumption, but we now know a lot more about inter-individual variability e.g. in the ratio of red:green cones and I can imagine that there may be people who find that red lights don’t work for them.
In the late 80ies / early 90ies, the US Navy came to the conclusion that there is no statistically significant difference in night adaptation between red light and low level white light at the same (perceived) brightness, and the US airforce decided to go back to white light.
Peter wrote:
Can’t they be sufficiently dimmed?
I haven’t found any commercial device like tablet or phone that could be dimmed sufficiently, and the GTN at least in my installation is still uncomfortably bright at max dimming.
The G1000 I fly with is too dim if I leave it on auto-brightness. I need to adjust the brightness manually to around 10% at night.
This was a big issue with most tablets I have tried. The Lenovo T2 does dim down nicely, as does the Samsung T700 / T705.
There is probably a significant difference between the technologies too. As I understand it on most devices even the black emits some light. But on (most) Samsung devices they use an amolded technology which doesn’t transmit any light for black. This should help reduce the light on an app that has a night mode for colours.
