Digital Obstacle File

Image:Digital obstacle file for Alabama.jpg

The Digital Obstacle File (DOF) describes all known obstacles of interest to aviation users in the United States, with limited coverage of the Pacific Ocean, the Caribbean, Canada and Mexico. The obstacles are assigned unique numerical identifiers and accuracy codes.

{{cite web

| url = https://nfdc.faa.gov/tod/public/TOD_DOF.html

| archive-url = https://web.archive.org/web/20130215101026/https://nfdc.faa.gov/tod/public/TOD_DOF.html

| url-status = dead

| archive-date = February 15, 2013

| title = Digital Obstacle File

| accessdate = July 25, 2012

| publisher = Federal Aviation Administration

}}

These downloadable products are available at least 21 days prior to their effective date. Data updates (also known as "chart updates") are coordinated over 56-day cycles.{{cite web|url=http://www.fedpubs.com/service/so_56day.htm|title=Standing Orders for 56-Day Cycle Aeronautical Publications and Charts|accessdate=September 17, 2009}} There are six to seven of these updates per year. Editions will be listed by year and 56-day cycle number; for example, Edition 200801 was the first 56-day cycle of 2008 (i.e. February 14, 2008).