Flying Inside the Box

What did we do before Google Earth?  Did we have paper charts and maps of stuff like roads and fields and stuff?  Did we have scales to everything when printers and copiers changed the size of everything?  I don't remember.  I have a vague recollection of considerably more work.

Our Jackson box is shown above, parallel to runway 6/24, which puts it perfectly over swampland but makes it a bit of a bugger to fly because it isn't square with all the wonderful section lines here in Michigan.  And runway 14/32 isn't quite orthogonal to it either.  Runway 32 was extended since this photo; the threshold of 14 is now just west of the middle of the box.  It can be hard to keep flight lines parallel to the box edges when not in a position to clearly see 6/24 from the air.

Runway 14/32 is closed during the competition, but 6/24 stays open for business at all times.

Combine Google Earth with a site like Calculate distance, bearing and more between Latitude/Longitude points (and there are many others, but this one did exactly what I needed) and laying out a box is really painless.  The site calculates distance between points specified by Lat/Long, and also gives the bearing between points and extrapolates points from known positions, given distance and bearing.  All the equations and code are explained also for those who need it, but I just used the plug and play features.

This box is exactly where our box was positioned last year, but I wanted to check it and re-plot it.

A competition aerobatic box is 3300' square (which is a smidgen over one square kilometer).  The east corner is positioned so that the box will sit northwest of runway 6/24 and west of the buildings between the runway and I-94 to the north, with at least a 164' buffer zone from edges of the aerobatic box to runway and buildings.

I set the east corner where it was last year.  The Lat/Long was obtained with a Google Earth marker; I projected the 3300' line parallel to the runway to obtain the south corner, defining the "front" of the box (SE edge).  Then adding 90 degrees to the bearing and projecting north and west corners was painless.  The website gives mid-points between lat/longs automatically, so the middle is easy to find.  I simply typed the Lat/Longs into Google Earth markers, took the screen shot into MS-Paint and threw the box lines in.  Nothing very sophisticated but this is all the FAA needs for depiction and is quite accurate.

We'll use a GPS when we place the box markers out in the fields, and the box will be within a few feet of a perfect size.  From the air it looks very nice and square, however cockeyed to the rest of Michigan as we know it.

The box goes to 3500 AGL, or almost exactly 4500 MSL at Jackson.  The lower limit depends on category, and the Unlimited base is only 328' AGL.  Since the box crosses I-94 just a little, there's a small wedge cut out of the north corner over I-94 which might only affect an Unlimited flight where the base is kept at 500' AGL.  The base for Advanced is 800' AGL and higher for other categories, so they are not affected.

We have line judges at the east and south corners, watching the SW and NE edges as well as the front edge along the runway.  The judges sit safely clear of 6/24 on the south side, almost box center and parallel to the front edge of the box.

So this picture will go in with the 7711-2 form, some pilot procedures documentation, and a page or two of IAC standards, and we'll see what the FAA folks need, if anything else, to approved this year's competition box.  It will be nice to have things in place early.