routes are routinely defined by just 4 segments: departure point (lat/long), first en route grid waypoint, last en
route grid waypoint prior to approach procedure, and destination point (lat/long). There are over 4,000 possible
offshore landing sites. Upon reaching the waypoint prior to the destination, the pilot may execute an Offshore
Standard Approach Procedure (OSAP), a Helicopter En Route Descent Areas (HEDA) approach, or an Airborne
Radar Approach (ARA). For more information on these helicopter instrument procedures, refer to FAA AC
90-80B, Approval of Offshore Standard Approach Procedures, Airborne Radar Approaches, and Helicopter En
Route Descent Areas, on the FAA website http://www.faa.gov under Advisory Circulars. The return flight plan
is just the reverse with the requested stand-alone GPS approach contained in the remarks section.
1. The large number (over 300) of waypoints in the grid system makes it difficult to assign phonetically
pronounceable names to the waypoints that would be meaningful to pilots and controllers. A unique naming
system was adopted that enables pilots and controllers to derive the fix position from the name. The five-letter
names are derived as follows:
(a) The waypoints are divided into sets of 3 columns each. A three-letter identifier, identifying a
geographical area or a NAVAID to the north, represents each set.
(b) Each column in a set is named after its position, i.e., left (L), center (C), and right (R).
(c) The rows of the grid are named alphabetically from north to south, starting with A for the northern
most row.
EXAMPLE-
LCHRC would be pronounced "Lake Charles Romeo Charlie." The waypoint is in the right-hand column of the Lake
Charles VOR set, in row C (third south from the northern most row).

2. In December 2009, significant improvements to the Gulf of Mexico grid system were realized with the
introduction of ATC separation services using ADS-B. In cooperation with the oil and gas services industry,
HSAC and Helicopter Association International (HAI), the FAA installed an infrastructure of ADS-B ground
stations, weather stations (AWOS) and VHF remote communication outlets (RCO) throughout a large area of
the Gulf of Mexico. This infrastructure allows the FAA"s Houston ARTCC to provide "domestic-like" air traffic
control service in the offshore area beyond 12nm from the coastline to hundreds of miles offshore to aircraft
equipped with ADS-B. Properly equipped aircraft can now be authorized to receive more direct routing,
domestic en route separation minimnd real time flight following. Operators who do not have authorization
to receive ATC separation services using ADS-B, will continue to use the low altitude grid system and receive
procedural separation from Houston ARTCC. Non-ADS-B equipped aircraft also benefit from improved VHF
communication and expanded weather information coverage.
3. Three requirements must be met for operators to file IFR flight plans utilizing the grid:
(a) The helicopter must be equipped for IFR operations and equipped with IFR approved GPS
navigational units.
(b) The operator must obtain prior written approval from the appropriate Flight Standards District Office
through a Letter of Authorization or Operations Specification, as appropriate.
(c) The operator must be a signatory to the Houston ARTCC Letter of Agreement.
4. Operators who wish to benefit from ADS-B based ATC separation services must meet the following
additional requirements:
(a) The Operator"s installed ADS-B Out equipment must meet the performance requirements of one of
the following FAA Technical Standard Orders (TSO), or later revisions: TSO-C154c, Universal Access
Transceiver (UAT) Automatic Dependent Surveillance-Broadcast (ADS-B) Equipment, or TSO-C166b,
Extended Squitter Automatic Dependent Surveillance-Broadcast (ADS-B) and Traffic Information.
(b) Flight crews must comply with the procedures prescribed in the Houston ARTCC Letter of
Agreement dated December 17, 2009, or later.

10-1-6

Helicopter IFR Operations