8/15/19 3/15/07 1/30/20 AIM  7110.65R CHG 2 AIM 6. Helicopter Route Charts. A three − color chart series which shows current aeronautical information useful to helicopter pilots navigating in areas with high concentrations of helicopter activity. Information depicted includes helicopter routes  four classes of heliports with associated frequency and lighting capabilities  NAVAIDs  and obstructions. In addition  pictorial symbols  roads  and easily identified geographical features are portrayed. Helicopter charts have a longer life span than other chart products and may be current for several years. Helicopter Route Charts are updated as requested by the FAA. Scale 1 inch = 1.71 nm/1:125 000. 34 x 30 inches folded to 5 x 10 inches. Revised biannually. (See FIG 9 − 1 − 4.) 1. IFR En Route Low Altitude Charts (Conterminous U.S. and Alaska). En route low altitude charts provide aeronautical information for navigation under IFR conditions below 18 000 feet MSL. This four − color chart series includes airways; limits of controlled airspace; VHF NAVAIDs with frequency  identification  channel  geographic coor- dinates; airports with terminal air/ground communications; minimum en route and obstruction clearance altitudes; airway distances; reporting points; special use airspace; and military training routes. Scales vary from 1 inch = 5nm to 1 inch = 20 nm. 50 x 20 inches folded to 5 x 10 inches. Charts revised every 56 days.  Area charts  show congested terminal areas at a large scale. They are included with subscriptions to any conterminous U.S. Set Low (Full set  East or West sets). (See FIG 9 − 1 − 5 and FIG 9 − 1 − 6.) b. IFR Navigation Charts. FIG 9 − 1 − 4 Helicopter Route Charts Types of Charts Available 9 − 1 − 4