Flying height from photo and map scale

The photo scale is found from a map distance, and then the flying height from $S = f/(H-h)$.

Step 1: Ground length of PQ

Map scale 1:50 000, so PQ on the ground:

$$PQ_{ground} = 6\ \text{cm}\times 50\,000 = 300\,000\ \text{cm} = 3000\ \text{m}$$

Step 2: Photo scale

$$S = \frac{\text{photo distance}}{\text{ground distance}} = \frac{0.20\ \text{m}}{3000\ \text{m}} = \frac{1}{15\,000}$$

Step 3: Flying height

$$S = \frac{f}{H-h}\ \Rightarrow\ H - h = f\times 15\,000 = 0.24\times 15\,000 = 3600\ \text{m}$$ $$H = 3600 + 350 = 3950\ \text{m}$$

Answer: The photo scale is 1:15 000 and the flying height of the aircraft is 3950 m above datum (3600 m above the average ground).