Using Auto ISO - and the Aviation environment.

I've always stayed away from auto ISO settings on my DSLRs.  There are some things that still draw me back to the 35mm days.  Could be I also didn't totally understand what limits or controls I could set.
I'm getting better at exploring higher ISOs than the 100, 200 and 800 that I was used to back in the day.  At the air races, I started one day at ISO 800.  Who was that guy?
I've gone through the total priority cycle.  That is I started at AUTO, then went to PRIORITY, tried SPEED and did a lot of time in MANUAL.  I'm most comfortable in PRIORITY.
The great part about the modes is they really allow you to shoot in AUTO with restrictions.  We'd all like to shoot MANUAL, just to say we can.  I can.  But I've missed shots.  And I don't want to say I shoot AUTO.
But command of the camera, the ability to modify the camera settings, quickly if necessary, to suit our situation is what we're going after.
When I'm shooting the model trains, I use MANUAL.  Simple reason is I have plenty of time and the environment never changes.  It's indoors.  The subject doesn't make any unexpected moves.  I get to review the shots.  If I need to re-take any images, it is doable.
When I'm shooting landscape, I use APERTURE PRIORITY.  I've found that I'm getting my best results with aperture settings higher than f/11 and more in the range of f/5.  Again the environment isn't changing too much or too fast.  I generally have an idea of what the speed is going to be and as long as it is over 1/250 I'm OK.  (1/250 will cover my 18-200 lens at max reach for simple speed guidelines.)
At the start of 2018 that was good enough for me.  Ah, the simple life.
In 2018 I had an 'expanding' year.  I found the fun of wildlife (Birds and Birds in Flight) and air races/shows.  While I've flirted with both subjects in the past, this year was time to up the game.
For the wildlife and BIF I shot MANUAL and APERTURE.  I missed too many shots (1) with MANUAL.  APERTURE was fine, but I think think I over planned and may not have had the best combination of APERTURE and ISO to get the best colors I could.  Area for improvement.
For aircraft in motion, both flight and ground operations, I have to get better.  I got lucky this year, but could have been much better.  Aircraft to me is probably the most difficult to get right because the action happens so fast, and the environment could change quickly and dramatically.  The subject moves from a cloud background to blue sky, then fly low over the ground.  No time to change stops and speed.  Oh yea, and there's a prop blur limitation.  Not that this is a problem, but a challenge.  
I need to solve the aviation environment.  If I can do that, all other environments will be controllable as well.
For the Aviation issue, the Exposure Triangle:
I need to shoot with SPEED priority.  If the subject were only jets, than speed is not a limiting issue.  But with props on both on fixed wing and helicopters, speed is the primary consideration.  From what I've seen, prop aircraft in flight should be less than 1/1000 sec and on the ground start at 1/80 sec and slower.  That takes care of the shutter speed side.
Aperture control is a personal thing with me.  As mentioned earlier, I like a nice open lens.  I'm a firm believer in reducing as much diffraction as possible.  I'd like to keep some control.  Shooting an aircraft in flight doesn't require a lot of DOF, especially if shooting with a sky background.  Unless there are multiple subjects.  I found f/5 and f/6 to do real well.  I'd like to set it and forget it.  That takes care of the aperture side.
Remaining is the ISO side.  Most cameras come with SPEED and APERTURE priorities.  There isn't a ISO priority.  Or is there?  Apparently with my Nikons, you can set the ISO to float with the SPEED and APERTURE fixed.  Why didn't I think of that?
I've found out that if you sent the camera mode to MANUAL and the ISO to AUTO, the ISO will float.  It is about that simple.  I can maintain some control over the ISO with the ISO - AUTO settings.
I think this will be a very cool setup for the aviation situations.  With the use of the command dials, I can change SPEED and APERTURE as I normally would in MANUAL.  Quickly.  And that completes the triangle.
This will be an awesome tool.  Will be looking forward to trying this out.
Another tool I'm looking to use is a neutral Density Filter.  I have a variable NDF, not a real good one.  I'd like to keep the filter at one piece of glass, but buying multiple filters is $$$$s.  First thing I need to do is get comfortable with the filter I have.  I have all winter, and when the snow hit the ground there will be lots of light to work with.  I also need to read more reviews.  If I do go with single, fixed filters, I need to figure out which one or ones to get.
Fortunately have time to work some of this out.  But not as much time as I thought.  The air races are in September.  However, I've committed to an air show in South Carolina in late April - about the time I'll need to thaw out from the Michigan winter.