Gas turbine start architecture and a method for starting such a turbine

A gas turbine starting architecture (10;60) is used to start a gas turbine engine having at least a first spool (14;64). The architecture includes an electric power distribution bus (46;96), a motor (40;92), a compressor (38;90), a pneumatic distribution circuit (36;98), an air turbine starter (34;86), and a first tower shaft (32;82). The motor (40;92) converts electric power provided by the electric power distribution bus (46;96) to mechanical power. In turn, the mechanical power provided by the motor (40;92) is converted to pneumatic power by the compressor (38;90) for provision to a pneumatic distribution circuit (36;88). The air turbine starter (34;86) converts pneumatic power from the pneumatic distribution circuit (36;88) to mechanical power is provided via the first tower shaft(32;82) to the at least one spool (14;64) on the gas turbine engine.