Turning off the terrain feature on the MFD (G1000) helps. And yes, the general level needs to be turned down manually for best night vision. It is done via the MENU button but only the PFD works for this. You need to know it to find it. On the Avidyne this is much simpler and more intuitive since screen dimming has its own hard wired buttons.
After having turned the light down manually you will usually forget to reset it to automatic after flight, so that the next pilot, who in all probability will fly in daylight, will wonder why the G1000 has gone black, and even if he recognises why, he will have a tough time resetting it with clues only from a dark screen in daylight.
Actually I need to turn the brightness UP rather than down at night on the G1000, and although I have not flown at night for a little while, IIRC the G1000 goes back to auto-brightness when you recycle it.
Actually I need to turn the brightness UP rather than down at night on the G1000, and although I have not flown at night for a little while, IIRC the G1000 goes back to auto-brightness when you recycle it.
Yes. In the 510/and Meridian there is a separate display brightness control. If you don’t adjust at night the auto brightness makes it almost back.
tomjnx wrote:
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.
Thanks for that really interesting link re. the navy – I couldn’t glean much from the airforce one.
I would point out that the navy conclusions were that red lights weren’t beneficial for submariners – hikers, astronomers etc… will be performing different visual tasks and so their findings, which were quite specific, won’t be generally applicable.
kwlf wrote:
will be performing different visual tasks
Why are the tasks we need to perform so different? We also need to recognize low contrast objects low on the horizon (terrain features). The other tasks, like recognizing the lit runway, or another aircraft are typically far above the mesotopic threshold (at least in a SEP), so quite easy.
I’m quite open to the idea that improvement in night vision gained by using a red light wouldn’t be useful to pilots – and probably the more sophisticated your aircraft, the less necessary it is. I have very little night flying experience myself so no real expertise. Arguably the 10 seconds to re-adapt could be too long for pilots, as things happen more quickly in aircraft than submarines. And you might expect to be able to see the lights on other aircraft more distantly if you use a red light because they’ll first appear as point sources below the mesopic threshold, becoming mesopic then photopic as they grow closer. But I can see that the rest is probably moot.
Hikers, on the other hand, need to recognise features such as a path or cliff edge, that might be defined by the contrast between one bit of ground and another, rather than the contrast between the sea and the sky (or the ground and the sky). And astronomers are looking specifically for point light sources – which is the sort of task where, according to the navy article, red-light adaptation has been proven to be advantageous. So whether a red light is beneficial is going to be very task-specific.
Funny coincidence! On my breadboard I have a circuit with RGB LEDs, a microcontroller and two rotary encoders with which I can adjust color/hue over the entire visible spectrum and brightness. The aim is to build an astronomy flashlight. I am waiting for some parts in the mail and then I am going to assemble and field test that thing. In astronomy, dark adaptation is much more important than in the cockpit. One really needs 30 minutes for full adaptation and one second of light can ruin that. I always found reading (star) maps under red light very difficult – for my eyes it is almost impossible to focus in dim red light – and will do some experiments with my “rainbow lamp”, clear nights permitting.
In the cockpit of a (civilian) aircraft it does not matter much. As others have said, the screens are so bright even at lowest intensity that no real dark adaptation will be achieved (*). Therefore the aircraft manufacturers have dumped the red lights decades ago.
* Just look outside the cockpit window at night with the lowest level of instrument lighting and count the visible stars. Hardly more than a few dozen, even in the stratosphere. After half an hour in your back garden, you can see 1000-2000 in a clear night.
My idea was to use a combination of a deep-red LED, a yellow/orange LED and a blue LED. The red LED would be the brightest – for good visual acuity. The yellow/orange LED would provide a degree of discrimination along the red-green axis, and the blue LED would provide a little discrimination along the blue-yellow axis, all the while whilst stimulating the rod system minimally. I had a multispectral illuminator to hand, that I’d made for other purposes. The idea wasn’t to make the colours look normal, but to provide a degree of colour information, whilst preserving night vision.
My recollection is that it worked – kind-of. It was very dependent on the maps, so would work for an ordinance survey map, but not for a colour photocopy. Another problem – again my recollection is dim – was that at least some of the blue LEDs caused the paper to fluoresce. One of the issues with looking at maps in red light is that you can’t see the red danger areas. With my light source you could… But they didn’t ‘pop out’ at you in the way that they usually do.
For the photopic regime, you can use a combination of red, green and blue lights in essentially any balance, and you still retain colour perception once you’ve adapted to the light. It doesn’t matter if you make the red light source 10 x brighter than normal – you might perceive that there’s a red cast to the light, but provided you have some green and blue light, you can still discriminate colour. I’m not aware of anybody testing this in the same way in the mesopic regime – not that I’ve looked – and would anticipate that if the green and blue lights are very dim, colour vision might fail. But in retrospect I can see that using a blended combination of RGB lights as you’re proposing might actually be the most practical proposition. I’d be interested to hear how it goes.
If I were to invent any night-vision gadget, it might be a pair of glasses that blacked out one eye instantly, if exposed to bright light, akin to some welding goggles that only blacken when you make an arc.
kwlf wrote:
I’d be interested to hear how it goes.
I will keep you informed once I have tested it. Just tonight I talked with a fellow amateur astronomer who is a biologist in real life. He was also interested in a variable color light because he thinks it could help him with microscopy, enhancing different colour contrasts. So I will make two of these “rainbow lights” for completely different purposes.
… it might be a pair of glasses that blacked out one eye instantly …
Quite a few astronomers do it that way, not with these instant LCD welding goggles, but with a pirate-style eye patch with which they preserve night vision for one eye all the time. I have tried that, but it gives me headaches and nausea if my eyes are illuminated in such an asymmetric way.
Long time no see… but finally my prototype “adaptive night vision lamp” is finished. The housing I bought was a tad on the small side, so a lot of tinkering was required to fit everything inside.
This picture shows the finished (so to say) lamp attached to a table using a photo clamp and a “magic arm”.
All this stuff is inside:
The lamp itself consits of 6 RGB LEDs that can be tuned to every colour of the rainbow. Additionally, the brightness and saturation (from “pure colour” to white) can be set. It is controlled by two rotary encorders with “click” function. One for ON/OFF and brightness, the other one for colour/hue and saturation, selectable by clicking the knob. Pressing the ON/OFF knob for long will store the current setting as default for the next power-up.
Additionally I added a 10W white LED (sufficient for a car headlight using the proper reflectors…) for white lighting. Astronomers need that for setting up their equipment during dusk and for locating parts that get dropped into high grass…
In order to prevent the bright white light to be turned on accidentally, I use a key switch for that.
Power supply is by XLR plug. 6V to 15V are acceptable with the voltage regulators and resistors I use, but the white LED will only work between 10V and 14V. A voltage sensing circuit makes sure that nothing goes wrong (during tests I fried two LEDs and one microcontroller, but now it should be OK…).
The heart of it all is an ATMEGA 328P microcontroller. I use an “Arduino Nano” board, because from eBay China than can be bought for 2 Euros, less than the chip alone would cost here. It comes with a voltage regulator (not stong enough for all the LEDs, so an external one is used here) and an USB interface that is very handy for quickly changing the software. And the “Arduino” software is quite easy to develop (C/C++) and runs on my Macintosh.
I know, Peter can make better PCBs than I, but mine are more colorful 
Over the next few weeks, I will try out on the telescope which colour and brightness works best with my night vision and let you know in due time.
