"I'm afraid that's outside my expertise, Ms. Brass." A parka-clad Cook raised his voice over the omnipresent rattle and vibration. The gondola's tube-steel structural network, trussed deck, and exterior cladding of thin corrugated sheet metal were built for minimum weight rather than maximum quiet or shelter. Even during high summer the interior was cold and drafty at cruising height, and it would only get worse as they continued north.