An aircraft is flying over the sea at FL 90

Question

ATPL - Airline Transport Pilot license - Meteorology - An aircraft is flying over the sea at FL 90

QuizVDS · Accepted Answer

The true altitude is 9100 feet

QuizVDS · Answer

Local QNH is unknown. What assumption, if any, can be made about the air mass in which the aircraft is flying ?

QuizVDS · Answer

There is insufficient information to make any assumption

QuizVDS · Answer

Its average temperature is the same as ISA

ATPL: An aircraft is flying over the sea at FL 90