I've been thinking about this for the few days that this has been discussed in here and the other thread. Rather than a spreadsheet, or dedicated E6B function, I'd rather have many of these features built into iFly. Density altitude could automatically calculated based on the weather report for the field, ADS-B, or other automatic inputs, and displayed on the airport information popup, and/or as an added insturment. If any of the information is missing, the field would have some indicator (????), clicking on it would prompt the user to input the necessary information.
Sunrise/sunset, Moonrise/set and phase I'd rather to see included in the airport information popup as well.
Knowing things like runway requirements I'd think could be included in the aircraft performance section where we can currently either accept standard performance figures for our aircraft, or enter specific values. If this was included I'd suggest some way to alert users if one of these values was outside our performance limitations. For example, when we looked at the airport information popup, the runway length might be flashing orange or red, indicating that there is some concern with the runway length as indicated by information known to iFly.
The problem I see with the spreadsheet, or E6B Plus type features is that those that regularly use such things likely already have dedicated apps, as well as the knowledge to use them. Therefore making their inclusion in iFly rather redundant and still likely not to be used by those that currently don't already have that knowledge or equipment.
In my case, I fly a C172 mostly in the midwest. Because nearly every runway around here is at least twice as long as needed for a C172, I rarely give a thought to these things. However, if/when I fly out west, I'd likely try to use the E6B Plus feature, but on approach to a high altitude airport is probably the wrong time to be trying to punch numbers into a screen suction cupped to my windshield. Seeing a red flashing runway length value would probably get my attention and I may be able to click on a nearby airport who's runway length was NOT flashing red.
Yes, I should have known this all in my pre-flight planning, but then I wouldn't need it in an active way in iFly. The problem is, we don't know, what we don't know. and other than trying to get my Skyhawk to 13K, I've never really experienced critical effects of density altitude.