The composition by category of Property, plant and equipment is as follows:
| Gross Book Value | Acumulated depreciation | Net Book Value | ||||||||||||||||||||||
| As of | As of | As of | As of | As of | As of | |||||||||||||||||||
| December 31, | December 31, | December 31, | December 31, | December 31, | December 31, | |||||||||||||||||||
| 2017 | 2016 | 2017 | 2016 | 2017 | 2016 | |||||||||||||||||||
| ThUS$ | ThUS$ | ThUS$ | ThUS$ | ThUS$ | ThUS$ | |||||||||||||||||||
| Construction in progress (*) | 556,822 | 470,065 | - | - | 556,822 | 470,065 | ||||||||||||||||||
| Land | 49,780 | 50,148 | - | - | 49,780 | 50,148 | ||||||||||||||||||
| Buildings | 190,552 | 190,771 | (66,004 | ) | (60,552 | ) | 124,548 | 130,219 | ||||||||||||||||
| Plant and equipment | 9,222,540 | 10,099,587 | (2,390,142 | ) | (2,350,045 | ) | 6,832,398 | 7,749,542 | ||||||||||||||||
| Own aircraft | 8,544,185 | 9,436,684 | (2,138,612 | ) | (2,123,025 | ) | 6,405,573 | 7,313,659 | ||||||||||||||||
| Other (**) | 678,355 | 662,903 | (251,530 | ) | (227,020 | ) | 426,825 | 435,883 | ||||||||||||||||
| Machinery | 39,084 | 39,246 | (29,296 | ) | (26,821 | ) | 9,788 | 12,425 | ||||||||||||||||
| Information technology equipment | 166,713 | 163,695 | (136,557 | ) | (123,981 | ) | 30,156 | 39,714 | ||||||||||||||||
| Fixed installations and accessories | 186,989 | 178,363 | (106,212 | ) | (94,451 | ) | 80,777 | 83,912 | ||||||||||||||||
| Motor vehicles | 70,290 | 96,808 | (58,812 | ) | (67,855 | ) | 11,478 | 28,953 | ||||||||||||||||
| Leasehold improvements | 186,679 | 192,100 | (102,454 | ) | (87,559 | ) | 84,225 | 104,541 | ||||||||||||||||
| Other property, plants and equipment | 3,640,838 | 3,005,981 | (1,355,475 | ) | (1,177,351 | ) | 2,285,363 | 1,828,630 | ||||||||||||||||
| Financial leasing aircraft | 3,551,041 | 2,905,556 | (1,328,421 | ) | (1,152,190 | ) | 2,222,620 | 1,753,366 | ||||||||||||||||
| Other | 89,797 | 100,425 | (27,054 | ) | (25,161 | ) | 62,743 | 75,264 | ||||||||||||||||
| Total | 14,310,287 | 14,486,764 | (4,244,952 | ) | (3,988,615 | ) | 10,065,335 | 10,498,149 | ||||||||||||||||
(*) As of December 31, 2017, includes pre-delivery payments to aircraft manufacturers for ThUS$ 543,720 (ThUS$ 434,250 as of December 31, 2016)
(**) Mainly considers rotable and tools.