Flight Path Above

I love to look at the great blue sky in sunny days. And I often see aeroplanes flying across, sometimes not one but few at the same time. Ipoh is not a bright spot in aviation map because the city's airport only serves very limited flights (probably just one or two). However, the sky above Ipoh seems to be busy with many commercial jets passing by. Even if I don't see it directly, the passed by aeroplane would draw lines in the sky just like the photo below.