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? Wrong solutions to Questions 1 and 2 on page 196 of Vol. 1

Werner Strauss created the topic: ? Wrong solutions to Questions 1 and 2 on page 196 of Vol. 1

Hello fellow self study people
Calculating ISA temperature is:
15 - (2 x elevation in thousands). The solutions to both question 1 and 2 on page 196 shows
1. Elevation is 5000 feet. In solution in the book the following is used
15 - 2 x 5.09

2. Elevation 1800 and solution states:
15 - 2 x 1.5

bobtait replied the topic: ? Wrong solutions to Questions 1 and 2 on page 196 of Vol. 1

To find the density height you must first correct for non-standard QNH. The QNH given is 1010hPa. That gives a pressure height of 5090ft (based on an approximate pressure lapse rate of 1hPa for each 30 feet of height increase) .

To find the density height we must first find the ISA temperature at that pressure height (based on an approximate temperature lapse rate of 2° for each 1000ft of pressure height increase). The pressure lapse rate and the temperature lapse rate are both approximations so, when calculating the ISA temperature, it is reasonable to round the pressure height to the nearest 500ft (there's no point in talking about fractions of one degree).

The steps are demonstrated clearly on page 194 & 195 of Volume 1.