It was observed that the initial ignition energy influences the flame deflagration characteristics of methane explosions. This distinct behavior has been noticed by a number of scholars, and in our laboratory scale explosion chamber recently. However, the flame traveling behavior has not been adequately clarified in industrial scale flame deflagration tube (FDT). This experimental work investigates methane flame deflagration and varied initial ignition in a large scale FDT (30 m long) facilitated at University of Newcastle, Australia, to comprehensively investigate methane flame deflagration behavior. The initial ignition energy was delivered by three alternative chemical ignitors' energies, which were 1, 5, and 10 kJ. The results of the study revealed the notable influences of the initial ignition energies on the flame deflagrations, over pressure rises, and pressure wave velocities along the FDT. When the initial ignition energy was increased from 1 kJ to 10 kJ, the maximum over pressure rises increased by 45% and 56%, respectively, for the 7.5% and 9.5% methane concentrations. For a 9.5% methane concentration, the increased ignition energy enhanced the pressure wave velocity from 130 m.s(-1) to 359 m.s(-1) and enhanced the flame deflagration velocity from 105 m.s(-1) to 179 m.s(-1).