In the Hercules world GTC would mean Gas Turbine Compressor. Small gas turbine engine that produces nothing but compressed air, and noise. A lot of noise. Compressed air is used for engine starting, air conditioning in the ground, and spinning an Generator via an air turbine motor. No idea what it would mean in the context of a 737.
Forgot to add: the GTC I'm talking about is a part of the airplane, vs the ground support cart plhought is describing. Although the turbine is essentially the same Garrett turbine in the carts.
Last edited by A Squared; 7th Aug 2016 at 17:15.