Aside from filling the crack with concrete patching compound with a latex additive, there isn't any major long term fix you can do on this as a DIY
It's from the 70s? It looks like asphalt. That's a really good lifetime, even if there is no car traffic on it, the weather would eventually have made things worse.
these are "real" planes there just not "big" planes
the issue is small electric and some of the bigger aerobatic birds with small wheels dont like the crack and you end up with only 1/2 the runway to work with
the big issue that stops any of this is making sure the crack doesnt come back
again one wants to spend the money only to have teh crack come back in 2 years
Which is why any fix applied just to the crack will never last long term. You don't build a house starting with the roof first, you build the basement upon firm ground. If the ground isn't firm, you dig down until it is.
As stated by others DYI repairs are going to only last a short time. That section needs to be cut out and then a new base install properly before the asphalt is applied. Overall considering the age it actually looks quite good.
Be glad you have any runway at all. This is our R/C aircraft field - »goo.gl/maps/7Txq
And what's with all the fencing at your field?
sarcasm It's so the TSA can do proper screening. How pray tell can you have any security without a fence?! Didn't you see the 2" high screeners in the grass? /sarcasm
Have you thought about making a sheet metal "plate" to cover the crack? If you get a strip of 16-18Ga galvanized steel about 8" wide and however long and lay it over the crack and fasten it down with a good calk the planes should roll over it with no issue. The 8" of course would straddle the crack, 4" on either side, and since 8' is a common length, 5 pieces should cover the 40' width.
Sheet metal should be strong enough for any reasonable load, except full size aircraft. This method would have the advantage of allowing the crack to expand and contract due to temperature changes on the pavement.
I have a similar crack in my driveway where two sections of pavement join. Over the years I have tried everything I can think of to repair and stabilize the crack. No luck. Of course since I drive cars over my pavement, a sheet metal bridge would not work.
If 0.059" is too big a bump, go with 22 or 24 ga. It does not have to support any serious weight, just stay flat.
Heck, I bet there is more than 1/16" in surface imperfections on the asphalt on the good part of the runway.
It may be possible to get the shop that shears it to hit it with a sander and break the edge so it has a little more lead in and smoother on the tires.