The Tevatron at Fermilab is the only collider in the world today with sufficient center-of-mass energy to produce top quarks. One remarkable characteristic of the top quark is its huge mass, Mtop ~ 180 GeV/c2, that makes it easily the heaviest particle in the Standard Model. The Run II of the Tevatron is now underway and one of the highest priorities of its physics program is an accurate measurement of Mtop. Indeed, a precise determination of this fundamental parameter of the Standard Model can be used to predict the Higgs boson mass that still eludes detection to date. In this talk I will present a preliminary measurement of the top quark mass using data collected by the CDF Run II detector. It will be demonstrated that the understanding of the jet energy scale is a determining factor in the precision of the top quark mass measurement, and an improved calibration using in situ W boson hadronic decays will be presented.