Determination of the primary energy by surface arrays (like AGASA) through estimators (instead of total size), taken as densities at 600 m from the shower axis, needs a special procedure for inclined cascades when the maximum is close to the array (less than 2-3 radiation lengths above). According to the cascade theory and the simulations with the CORSIKA code above 10 EeV the exponential function used for /rho(600) conversion from inclined to vertical showers is no longer valid. As follows from simulations at energies near to 100 EeV, the density at 600 m for zenith angles 25-35 exceeds by 10% the vertical density, whereas it was assumed to be 30% lower in the previous treatments. Such treatments generate an artificial increase in the estimation of the primary cosmic ray energy. The primary spectrum reconstructed by an appropriate procedure for inclined showers confirms GZK prediction and eliminates the divergence between measurements at ultra-high energies
