heres another one guys:
You are flying over the sea at FL 250 and measure an outside temperature of -50°C. The pressure at sea level is 1023 hPa. What is your approximate true altitude calculated using normal vertical change in temperature with increase in height?
(a) 23230'
(B) 26770
(C)26230
(D) 23770
answer is D....can anyone enlighten me as to how to work out that exact figure?
thanks!