Ndegi
Certainly the Spider Track is superior, BUT very expensive compared to Spot. For most pilots Spot is quite adequate and much more affordable.
By the way Spot does work while airborne, I have a friend who I have tracked crossing the Atlantic Ocean with Spot. There must be a problem with your unit or the way you are using it. Where do you mount the unit? It needs to be able to see the satellite so needs to be somewhere like the front window.