We’re not talking about the cockpit temps humans experience. Humans don’t sit in the panel. Hold your finger to the front of a Garmin on a 34° day after a 3hr flight and tell me you didn’t burn it. Same applies to a box that is cold-soaked in an aircraft that sat outside overnight at -45° (common winter overnight temps in Canada & Alaska).
Is that another way of saying the Garmin design in general and cooling in particular is so poor (especially given the low computing power involved) that it cannot cope with normal temperatures without becoming hazardous to the user? If yes, I agree. I don’t see how anybody is supposed to operate a “certified” electronics box that runs at 80C surface temp.
Re – cold soaked box, it will surely heat up a lot faster than the cockpit will. If it doesn’t, I don’t think it matters much. With -40C gloves on you’re unlikely to be able to operate it anyway.
At the bottom end, you have to be able to get into a certified aircraft, at say -30C (with the piston engine preheated, obviously, but that’s not the avionics mfg’s problem), switch everything on, and it has to basically work, within say 1 minute. I am sure there is a spec…
At the top end, you have to be able to get into a certified aircraft, at say +50C (hot summer day, etc), switch everything on, and it has to basically work.
With non-LCD products, neither is generally a problem. AHRS devices will take longer to reach the stabilised oven temperature when it’s cold but that doesn’t usually matter because you are doing other stuff.
The top end is easier to do but avionics life expectancy will be badly affected if there isn’t enough cooling. For example the back of the Aspen EFD-1000 is too hot to touch just sitting on a bench, dealer demo, in the open air! No idea how hot it gets when in the panel, and there is no avionics fan directing air to where that product is mounted (normally only the centre stack gets forced air).
The bottom end is OK (non-LCD) if you can obtain everything in industrial (automotive) temp range, which can sometimes be hard but is doable.
LCDs are probably the fun bit but I am out of date on that.
I wonder if such a low temp spec actually exists for certification (supposing for a minute you could operate modern avionics in -40C proof gloves and do a generally good job at flying).
If a spec covering cold soaked operations and requiring the product to be “on spec” the moment you turn it on does indeed exist I wonder how piston engine manufacturers got their products certified…
I learned to fly in central Canada and the flying club only shut down ops below -35 because the instructors would strike, not the aircraft/avionics. Airbus does/did their certification testing in northern Canada for just that reason – to “simulate” 
the certification requirements. BTW, training at -35 in a C152 is a student’s dream due to improved performance. But I guess that’s getting quite a bit off-topic.
modern hi-res and can have the availability assured for say 10-15 years
Forget it. Completely. The only thing that would survive over that time frame is the parallel interface to 5×7 pixel monochrome character LCDs.
You all have much too high expectations of your avionics. Most cockpit mount avionics is tested to somewhere between -15°C..55°C or -20°C..70°C
KSN 770 First in a Bonanza
Aircraft: F33
I came from the Garmin world, where I was not happy. My analogy would be the Garmin is the PC of integrated avionics, the Bendix King KSN770 is the Apple.
The user interface is far superior. The unit includes a full map background similar to ForeFlight with Sectionals, low and high altitude IFR enroute. There’s a second data base from Seattle Avionics (nee ASPEN) which includes all the nav data,plates, airport diagrams etc.The screen is large enough to be subdivided. Cut it vertically and you can show the FMS on the left and nav map/flight plan on the right or you can show terrain on the left at the same time the nav map is displayed on the right. You can adjust scale of the left and right sides independently. You can further subdivide the left side horizontally so you have 3 concurrently displayed screens.
Flight planning function is easier than Garmin. You enter the flight plan thru the FMS. You can display the FMS screen as shown in the photo I posted and modify the flight plan from it at any time. Controller sending you to another waypoint on an approach downstream from where you are? Just touch the waypoint he’s sending you to to highlight and push the joystick to enter, you’re now going to the new waypoint and the remainder of the approach will seqence normally.
I like the joystick control. It has several functions and is easy to control even in turbulence. It has a touch screen but like the 650 and 750 you can also access all functions via hard and soft keys. I’m still learning it but lets just say I flew a 430W for four years and never really felt like I got comfortable with it. There are just too many ways to get lost in the interface. I’ve flown the KSN 770 for about 20 hours now and I feel as good about it as I did the Garmin. The interface to the KI 525 HSI is and the STec 50 are excellent. Of course it’ll work with an Aspen too, and there is a relationship between King and Aspen since they used the Aspen STC’s for approval, but my humble opinion is the Aspen to too expensive for what you gain to replace a good HSI.
This is the whole setup. iPad w/ ForeFlight on a RAM yoke mount.
Split screen showing FMS on the left and MFD on the right. Note the flight plan/ approach is displayed at the top. Also note the standby freq GGG Approach is identified below the freq display. Note also the soft key on the left margin id’d as VTF, Vectors to Final. Push that if flying vectors and the whole sequence is shown and will start guidance automatically at the IAF.
Split screen showing Nav map on the MFD at the right side. We’re low enough now, 1500 AGL that towers are starting to show up, you can turn them off in settings if you want. Terrain map shown on the left note different scales on the two maps. You could subdivide the left side again and show traffic on another screen.
If I could comment on some older posts on this thread, we are buying all sorts of TFT displays for Automotive projects, and we have to support them for many years (spares). Automotive spec is -40 to +85.
As for waiting, if you switch on the standby gyro on a new Citation CJ2+ it takes 3 minutes to be usable. If you move before the 180 sec countdown has finished it starts again!
Neil wrote:
we are buying all sorts of TFT displays for Automotive projects
The question is what volumes. I’d be surprised if the volume wasn’t at least 100 times larger than typical avionics batch sizes.
Check out
https://Vimeo.com/133566388
