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6/17/21 

AIM 

(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

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) Equip-

ment, 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. 

NOTE

 

The unique ADS

B architecture in the Gulf of Mexico 

depends upon reception of an aircraft’s Mode C in addition 
to the other message elements described in 14 CFR 91.227. 
Flight crews must be made aware that loss of Mode C also 
means that ATC will not receive the aircraft’s ADS

signal. 

5. 

FAA/AIS publishes the grid system way-

points on the IFR Gulf of Mexico Vertical Flight 
Reference Chart. A commercial equivalent is also 
available. The chart is updated annually and is 
available from an FAA approved print 
provider 

or 

FAA 

directly, website address: 

http://www.faa.gov/air_traffic/flight_info/aeronav. 

Helicopter IFR Operations 

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