[expatpat]

Not necessarily, I think. If the heat system to the cabin failed, the temperature in the cabin would drop very fast, epecially if the pressurization ws still operating. The outside air at 35,000 ft can be -50 degrees, easily.

[Nov3]

Not necessarily, I think. If the heat system to the cabin failed, the temperature in the cabin would drop very fast, epecially if the pressurization ws still operating.

IIRC The heat and pressure systems are inter-related - heat of compression - if the pressure system fails - no heat.