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AIM

10/12/17

10−1−6

Helicopter IFR Operations

than that published in the procedure, until canceling

IFR.

(c) IFR obstruction clearance areas are not

applied to the VFR segment between the MAP and

the landing site. Obstacle or terrain avoidance from

the MAP to the landing site is the responsibility of the

pilot.

(d) Upon reaching the MAP defined on the

approach procedure, or as soon as practicable after

reaching the MAP, the pilot advises ATC whether

proceeding VFR and canceling IFR, or complying

with the missed approach instructions. See para-

graph 5−1−15, Canceling IFR Flight Plan.

(e) If the visual segment penetrates Class B,

C, or D airspace, pilots are responsible for obtaining

a Special VFR clearance, when required.

10−1−4. The Gulf of Mexico Grid System

a. On October 8, 1998, the Southwest Regional

Office of the FAA, with assistance from the

Helicopter Safety Advisory Conference (HSAC),

implemented the world’s first Instrument Flight

Rules (IFR) Grid System in the Gulf of Mexico. This

navigational route structure is completely indepen-

dent of ground−based navigation aids (NAVAIDs)

and was designed to facilitate helicopter IFR

operations to offshore destinations. The Grid System

is defined by over 300 offshore waypoints located 20

minutes apart (latitude and longitude). Flight plan

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 Circu-

lars. 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 Interna-

tional (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 minima and 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: