Airport

Cost	$20,000,000
Inputs	20x jet fuel, 20x energy
Outputs	$1,000
Production interval	Variable (1:00 - 0:30)

Airports have a variable production interval which changes depending on how many total airports you have built in the current region.

Production Interval Table

Airports in region	Production interval
1	00:30
2	00:31
3	00:31
4	00:32
5	00:32
6	00:33
7	00:33
8	00:34
9	00:34
10	00:35
11	00:36
12	00:36
13	00:37
14	00:38
15	00:38
16	00:39
17	00:40
18	00:41
19	00:41
20	00:42
21	00:43
22	00:44
23	00:45
24	00:46
25	00:47
26	00:49
27	00:50
28	00:52
29	00:54
30+	01:00