Why start a coup when you don't control the air force or other important elements in the army? I suppose this was a desperate, final stand against Erdogan but it only ended up helping him become more powerful.
Also, the purges he made in the army a few years back seem to have come to fruition, they are probably why only parts of the army were involved in the coup.
I'm surprised that some of the posters here wanted the coup to succeed. It was not supported by the opposition or the Kurds, I doubt it would've led to a better Turkey had it succeeded.