Air Traffic Bulletin

Issue 00-1 WINTER 1999 - 2000

Table of Contents: [Back]
High Altitude Turn Anticipation
Flight Data Block (FDB)/Target Markers
Say the Magic Words
I Can See Clearly but the Viz is Gone
Warning Areas and Offshore Airspace (Correction to Previously Published Article)
Controlled Flight into Terrain (CFIT) Avoidance (Correction to Previously Published Article)

High Altitude Turn Anticipation

/*ET/ In response to earlier reports of certain aircraft beginning to turn a significant distance from a fix, we have worked closely with Flight Standards (AFS) and industry representatives to determine the extent of the problem and what some of the solutions might be.

The reports and our research indicate that the problem involves Airbus aircraft; specifically, the A-319/320/321, making turns greater than 70 degrees above flight level (FL) 180. Additionally, we have learned that the A-330 also has the same characteristic. The root cause of the problem is these aircraft have been designed, for reasons of passenger comfort and aerodynamics, to make what we would consider shallow turns at altitude. We have verified that the aircraft will commence to turn as much as 15-20 miles from the fix. However, when these aircraft reach 5 miles laterally, they will hold that distance and the new track will parallel the original route until approaching the fix, at which time the aircraft will continue to complete the turn toward the next fix.

This article is intended to inform controllers working high-altitude sectors of the following information:

a. Airbus aircraft will begin to turn "early" for turns of greater than 70 degrees at or above FL 180.

b. The lateral displacement of the parallel track and the distance from the fix at the turn may exceed the procedural route width of 4 miles.

c. Reestablishment on the centerline of the follow-on route may be greater than what is expected from other type aircraft.

In addition to informing the controller work force, we will also be notifying those organizations responsible for procedure development to avoid establishing procedures and routes requiring large turns above FL 180.

We will continue working with AFS to review departure criteria and policy and effect changes where appropriate. Additionally, AFS intends to advise Airbus operators of this issue and will recommend their flight crews be made aware of this early turn characteristic. Further, AFS intends to advise manufacturers of the issue and the requirement to address the need to resolve this operational problem. Lastly, AFS will request the Aircraft Certification Service to assess its approval process of high-altitude turn algorithms. (ATP-100)

Flight Data Block (FDB)/Target Markers

/*ET/ FDB/target markers are a controller's primary means of tracking aircraft in today's radar environment. A radar controller's worst nightmare is to lose the radar display or to be deprived in some way of the identity of the aircraft that are operating within his/her airspace. The requirement to continuously maintain the identity of individual aircraft through target markers or the FDB has been in place since the advent of radar use in the air traffic control system. Regardless of the official requirement, common sense would dictate that the FDB be displayed until the aircraft is no longer within one's airspace. Yet today, a fair number of operational errors and deviations still occur due to the intentional premature removal of the FDB.

In May 1999 GENOT 9/25 was distributed to all field facilities to highlight this issue and prevent unnecessary errors. The GENOT requires FDB/target markers to be continuously displayed until the associated aircraft has left the sector airspace, the delegated airspace and all potential conflicts have been resolved, including point out aircraft. As a minimum, the FDB must display the aircraft ID and its altitude status.

However, on January 28, 2000, an en route ATCS in the western part of the country dropped the data block of an aircraft prior to its leaving the sector airspace. The ATCS forgot about the aircraft and descended another aircraft through it. The MD80 and the B737 missed each other by 500 feet and 3.5 NM. The following day, an en route ATCS in the midwest was given control for descent of a DC9 approaching the sector boundary southeast bound. The ATCS dropped the FDB of a westbound B727 when it crossed the sector boundary, forgot about it, and descended the DC9 through it. The aircraft passed 2.4 NM and 1,300 feet from each other. The GENOT was distributed last May in an effort to eliminate an unnecessary cause of separation loss.


Say the Magic Words.....

/*ET/ And you'll win no errors. (Apologies to Groucho Marx.) The rules for the application of visual separation between aircraft are simple enough, yet a handful of specialists still get caught in a loss of separation. The process of transferring the responsibility for separation between aircraft from the controller to the pilot is not complicated, but it does require some precise transfer of information on the controller's part.

The use of visual separation may be broken down into 4 parts:

1. POINT OUT the aircraft to the pilot. (Tell pilot where it is and what it is doing.)

2. VERIFY that the pilot sees the aircraft.

3. INSTRUCT the pilot to maintain visual separation from the aircraft.


Omitting any of the last 3 steps will result in a loss of separation if the aircraft closes to less than standard separation from each other. Even if the pilot later (or during the event) says he/she is maintaining visual separation, it will be too late for the controller to avoid an error. (AAT-200)

I Can See Clearly but the Viz is Gone

/*ET/ Visual separation, as a tool, had been available only to the terminal ATCS until recently when its use was expanded to include the en route ATCS. However, the use of visual separation is still restricted to aircraft operating below FL 180. In other words, visual separation cannot be used in Class A (formerly Positive Control) airspace. Instances of inappropriate use of visual separation began to appear in the system when terminal controllers attempted to apply visual separation in terminal airspace that extended above FL 180 by virtue of the fact that the airspace was delegated to the terminal facility on a permanent basis. In addition, En route specialists attempted to apply visual separation between aircraft operating at FL 180 and aircraft making a transition above or below FL 180. Neither of these applications is correct.

FAAO 7110.65, paragraph 7-2-1, Visual Separation, contributed to the terminal controller confusion because the "Terminal" paragraph did not indicate that the use of visual separation was prohibited in Class A airspace. During the interim awaiting the change to the order, GENOT 9/55 was disseminated to all field facilities to clarify the procedure. Frequently, the mistakes made by controllers in both options are due to the failure to instruct the pilot to maintain visual separation. (See the article above, "Say the Magic Words...") The other mistake that is made is attempting to use visual separation when one or both of the aircraft are still in transition from Class A airspace. (AAT-200)

Warning Areas and Offshore Airspace

(Correction to Previously Published Article)


/*E/ The following is a correction to the article titled "Warning Areas and Offshore Airspace" published in ATB 99-3. For your convenience we have re-printed the entire article, as it should have appeared, directly below this table.

Currently Published in ATB 99-3

Revision to ATB 99-3

According to FAAO 7400.2D, Procedures for Handling Airspace Matters, Offshore Airspace Areas are designated between the U.S. 12 NM territorial limit and the oceanic CTA/FIR boundary. There has been some confusion over whether this meant the CTA/FIR boundary closest to, or farthest from, the U.S. The correct interpretation is that Offshore Airspace Areas extend out to the CTA/FIR boundary closest to the U.S. in order to facilitate the use of domestic procedures. Within the CTA/FIR area itself, ICAO oceanic ATC procedures are used instead of domestic procedures.

According to FAAO 7400.2D, Procedures for Handling Airspace Matters, Offshore Airspace Areas may be designated for aircraft operations between the U.S. territorial limits and the oceanic CTA/FIR boundary and /or domestic point-to-point flights which operate in part over the high seas. These areas are established to permit the application of domestic air traffic control services. There has been some confusion over whether this meant the CTA/FIR boundary closest to, or farthest from, the U.S. The correct interpretation is that Offshore Airspace Areas may extend out to the U.S. CTA/FIR boundary. Within the CTA/FIR area itself, ICAO oceanic ATC procedures are used instead of domestic procedures.



Warning Areas and Offshore Airspace

/*E/ In February 1997, an Air National Guard F-16, operating in warning area airspace over the Atlantic Ocean, intercepted a Nations Air Boeing 727 (B-727) that was traversing the warning area on an IFR flight plan. The proximity of the F-16 activated the B-727's Traffic Alert and Collision Avoidance System (TCAS), requiring the B-727's flight crew to execute several maneuvers in response to the TCAS Resolution Advisories.

The National Transportation Safety Board investigated this incident and identified concerns in the areas of communications, coordination procedures, and responsibilities for the separation of aircraft transiting warning areas.

The FAA and the DOD also investigated the incident and conducted a joint review of procedures to determine if there is a need for additional guidance on the joint use of warning areas. The review found that existing letters of agreement (LOA) or memoranda of understanding (MOU) provide adequate guidance and procedures for the activation, deactivation, and joint use of warning areas, and that these procedures, when properly adhered to, are satisfactory. The FAA/DOD review group noted, however, that some confusion exists over the classification of offshore airspace, the status of warning areas, and the operating rules and separation standards that apply when nonparticipating aircraft transit a warning area.


International Civil Aviation Organization (ICAO)

ICAO is an agency of the United Nations that originated from the signing of the Convention on International Civil Aviation in December 1944 (referred to as the Chicago Convention). This organization was formed to promote the safe and orderly development of international civil aviation. The Chicago Convention produced International Standards and Recommended Practices (SARP) aimed at standardizing international civil aviation operational practices and services. Currently, these SARP's are contained in 18 annexes to the Chicago Convention. In particular, Annex 2, Rules of the Air, and Annex 11, Air Traffic Services, are pertinent to this paper as they relate to civil aircraft operations, the establishment of airspace, and air traffic control (ATC) services in international airspace. Although not addressed in this paper, it should be noted that the SARP's are augmented by various ICAO documents containing Procedures for Air Navigation Services (PANS) that amplify the basic principles in the SARP's. Further, to supplement the worldwide procedures contained in the annexes and PANS, ICAO develops Regional Supplementary Procedures, which are part of the Air Navigation Plans agreed upon to meet the needs of specific geographical areas.

Two articles of the Chicago Convention also have a bearing on the subject of this paper:

Article 3:

Exempts state-owned aircraft (which includes military aircraft) from the provisions of Annex 11 and its Standards and Recommended Practices. (Note: As an ICAO Contracting State, the U.S. has agreed that its state aircraft will be operated in international airspace with due regard for the safety of civil aircraft.)

Article 12:

Obligates each ICAO Contracting State to adopt measures to insure that persons operating an aircraft within its territory shall comply with that state's air traffic rules; or with Annex 2, Rules of the Air, when operating over the high seas. The U.S. satisfied this responsibility through Title 14, Code of Federal Regulations (CFR) Part 91 which requires that operators of aircraft comply with U.S. operating rules when in the U.S., and that U.S.-registered aircraft comply with Annex 2 when over the high seas (see section 91.703). However, section 91.703 applies only to civil aircraft, and state aircraft operating outside the U.S. are only subject to the "due regard" provisions of Article 3 of the Convention.

Under ICAO agreements, the SARP's in Annex 11 apply to airspace under the jurisdiction of a contracting state which has accepted the responsibility of providing air traffic services over the high seas, or in airspace of undetermined sovereignty.

ATC Services

The U.S. has accepted responsibility for providing oceanic air traffic control services within Flight Information Regions (FIR) in a portion of the western half of the North Atlantic, most of the Gulf of Mexico, and a large portion of the North Pacific. Within these Control Area (CTA)/FIR's, the U.S. applies oceanic separation procedures consistent with ICAO regional procedures. These procedures are contained in FAAO 7110.65, Chapter 8, Oceanic/Offshore Procedures.

The FAA applies domestic ATC procedures within airspace over the U.S. and adjacent waters out to the 12 NM limit. In accordance with Annex 11, the FAA may also apply domestic ATC procedures within designated offshore controlled airspace (within areas of domestic radio navigational signal or ATC radar coverage) from the 12 NM limit outward to the inner (i.e., closest to the U.S.) CTA/FIR boundaries. ICAO agreements permit the application of domestic ATC procedures even though this is international airspace. (Note: Either domestic or ICAO procedures could be used in offshore controlled airspace depending on the extent of navigational signal or radar coverage in the area.)

U.S. Domestic Airspace Limit

Until December 1988, the U.S. territorial limit was set at 3 NM from the coast of the United States. On December 27, 1988, President Ronald Reagan signed Proclamation No. 5928 which extended the territorial sea of the United States out to 12 NM from the coast.

To accommodate the territorial extension, the FAA amended 14 CFR Parts 71 and 91 to extend controlled airspace (Class E and Class A), and the applicability of certain flight rules, to include the airspace overlying the waters between 3 and 12 NM from the U.S. coast. This FAA action was necessary for the U.S. to extend its domestic air traffic control authority and procedures over airspace that is no longer considered a part of the high seas; and to require operators to comply with FAA flight rules rather than ICAO Rules of the Air in that airspace.

The presidential proclamation also had an immediate impact on the status of a number of existing warning areas that were established based on the former 3 NM territorial limit. This warning area issue will be discussed later in this paper.

U.S. Domestic Airspace Classification

In 1993, the FAA reclassified U.S. airspace by adopting the airspace classes recommended by ICAO. Probably the most familiar feature of the airspace reclassification is the replacement of "old" terms such as "Positive Control Area," "Terminal Control Area," "Control Zone," etc., with ICAO letter classifications (Class A, B, C, D, etc.).

Offshore Airspace

Also in 1993, the FAA issued the "Offshore Airspace Reconfiguration" rule which supplemented the domestic airspace reclassification effort. In part, the Offshore rule redesignated certain "additional control areas," over international waters, as "Offshore Airspace Areas." This part of the rule provided for the designation of Class A or Class E airspace, in international airspace, within areas of domestic radio navigational signal or ATC radar coverage, and within which domestic ATC procedures are applied.

According to FAAO 7400.2D, Procedures for Handling Airspace Matters, Offshore Airspace Areas may be designated for aircraft operations between the U.S. territorial limits and the oceanic CTA/FIR boundary and/or domestic point-to-point flights which operate in part over the high seas. These areas are established to permit the application of domestic air traffic control services. There has been some confusion over whether this meant the CTA/FIR boundary closest to, or farthest from, the U.S. The correct interpretation is that Offshore Airspace Areas may extend out to the U.S. CTA/FIR boundary. Within the CTA/FIR area itself, ICAO oceanic ATC procedures are used instead of domestic procedures.

As mentioned above, Offshore Airspace Areas are still international airspace, but under ICAO agreements, the FAA may apply domestic ATC separation procedures in those areas. It is important to reiterate that state aircraft are subject only to the "due regard" provisions of the Chicago Convention when operating beyond 12 NM from the U.S. coast.

DOD Policies Regarding Operations in International Airspace

Military aircraft are considered to be "state" aircraft and, as such, the DOD may elect to conduct certain operations in international airspace under "due regard" instead of ICAO flight procedures.

DOD policies regarding the use of ICAO procedures and military operations over the high seas are stated in DOD Flight Information Publication (FLIP), General Planning, Chapter 6, International Civil Aviation Organization; and Chapter 7, Operations and Firings Over the High Seas. These policies are summarized in the following excerpts from the FLIP, General Planning:

- The airspace beyond the territorial sea is considered international airspace where the permission of the coastal state is not required for overflight or related military operations. Military aircraft operating in international airspace are not legally subject to the jurisdiction or control of air traffic control authorities of a foreign country.

- Although ICAO rules and procedures are binding upon civil aviation only, military aircraft are expected to avoid conflicting with national regulations. Normally, routine point-to-point and navigation flights shall follow ICAO flight procedures.

- It is the policy of the DOD that all United States military aircraft and firings shall operate with due regard for the safety of all air and surface traffic. When practical and compatible with the mission, U.S. military operations on the high seas shall observe ICAO flight procedures.

- Operations not conducted under ICAO flight procedures are conducted under the "Due Regard" or "operational" prerogative of military aircraft, subject to one or more ... conditions ... [which] ... provide for a level of safety equivalent to that normally given by ICAO ATC agencies. Flight under these provisions shall be regarded as deviations from normally accepted operating procedures and shall not be undertaken routinely.

For more information about pilot responsibilities when operating under "due regard," refer to the "Terms of Reference" section in FAAO 7110.65L, Chapter 1; or FLIP, General Planning.

Warning Areas

A warning area is one of the six types of special use airspace (SUA) areas. Warning areas contain activities that may be hazardous to nonparticipating aircraft. These areas may contain a wide variety of aircraft and non-aircraft activities, such as: aerial gunnery, bombing, aircraft carrier operations, surface and subsurface operations, naval gunfire, missiles, etc. Although warning areas may contain hazards similar to those found in a restricted area, the U.S. does not have the authority to prohibit flight by nonparticipating aircraft in international airspace. Therefore, warning areas are designated to alert nonparticipating aircraft to the potential danger.

To more fully understand the current status of warning areas, it is necessary to review the changes that have occurred since 1988.

Originally, warning areas were only designated over international waters, (beyond the former 3 NM limit). When the President extended the territorial sea out to 12 NM, the airspace between 3 and 12 NM from the coast was no longer considered international airspace. This immediately caused many existing warning areas to lie partly within domestic airspace instead of being located totally within international airspace, as called for by the warning area establishment criteria. The issue was further complicated by the FAA's extension of controlled airspace (Class E and Class A), and Part 91 operating rules out to 12 NM, because this would have prohibited the DOD from conducting hazardous activities in that 3 to 12 NM segment without either an exemption to the regulations, or the designation of another type of SUA. This situation would have adversely impacted military training and/or prevented access by nonparticipating aircraft to airspace where they have freely operated for years.

To allow the continuation of ongoing military activity in the existing warning area segments between 3 and 12 NM, and to preserve the right of nonparticipating aircraft to fly through these areas, the FAA issued Special Federal Aviation Regulation No. 53 (SFAR 53).

SFAR 53 established regulatory warning areas between 3 and 12 NM from the coast. The SFAR used the terms "warning area" to identify these regulatory warning areas, and "nonregulatory warning area" to indicate those areas beyond 12 NM, located entirely over international waters.

SFAR 53 specifically stated that Part 91, Subpart B, applies within the regulatory warning areas. However, the SFAR further stipulated that pilots of participating aircraft, operating in a warning area with the approval of the using agency, may deviate from the rules of Part 91, Subpart B, to the extent that the rules are not compatible with the mission. Nonregulatory warning areas were not affected by the SFAR.

The SFAR was intended to be an interim measure with the sole purpose of enabling the continuation of military training activity, and maintaining the right of nonparticipating aircraft to fly through those portions of warning areas located between 3 and 12 NM from the coast, while a permanent solution was developed.

After the presidential proclamation was issued, the DOD adjusted the boundaries of numerous warning areas outward to 12 NM. However, DOD requirements called for certain warning areas to remain at 3 NM. The FAA then faced the dilemma of how to accommodate DOD's requirements between 3 and 12 NM from the coast without taking action that would impose an undue burden on nonparticipating aircraft (e.g., fish spotters, etc.) which had flown in the 3 to 12 NM offshore portion of warning areas for decades.

Following considerable study of this issue, the FAA decided that the best solution was to adopt a new definition of warning areas that incorporated the provisions of SFAR 53 and combined the SFAR 53 definitions in a single term. The FAA implemented this decision by issuing the "Definitions of Special Use Airspace" rule which codified all SUA definitions, including warning areas, and incorporated them into 14 CFR Part 1. This rule consolidated the SFAR 53 definitions of "warning area" and "nonregulatory warning area," into a single term that applies in both domestic airspace (located between 3 and 12 NM from the U.S. coast), as well as international airspace, beyond the 12 NM limit. The FAA determined that the combined definition is appropriate since the procedures that apply to the two warning areas are the same. This new definition, which became effective when SFAR 53 expired on January 15, 1996, reads as follows:

"Warning area: A warning area is airspace of defined dimensions, extending from 3 nautical miles outward from the coast of the United States, that contains activity that may be hazardous to nonparticipating aircraft. The purpose of such warning areas is to warn nonparticipating pilots of the potential danger. A warning area may be located over domestic or international waters or both."

The effect of this change is that existing warning areas may continue to be located in domestic airspace, beginning 3 NM from the U.S. coast. The DOD may continue to conduct hazardous activities there, and nonparticipating pilots are warned about the presence of hazards, but are not prevented from entering the area. Furthermore, Part 91, Subpart B, does apply in that portion of warning areas between 3 and 12 NM from the coast; but, when the warning area is active, participating pilots may deviate from the rules to the extent that they are not compatible with the mission.

Joint Use of Warning Areas

It is FAA policy that all SUA, including warning areas, should be made available for use by nonparticipating aircraft when all or part of the airspace is not needed by the using agency, provided there is no derogation to the using agency's mission.

Notwithstanding the above, the FAA will not route nonparticipating IFR aircraft through an active warning area unless provided for in an LOA. Otherwise, FAA will clear nonparticipating aircraft via routing which will provide approved separation from the airspace.

To initiate joint use of a warning area, an LOA is executed between the controlling agency and the using agency. These LOA's are prepared on a site-specific basis in order to accommodate the unique circumstances of each particular location. The LOA provides for the activation and deactivation of the warning area and defines the conditions under which nonparticipating aircraft may be authorized to operate within or through the area. The incident described at the beginning of this article highlights the importance of the LOA in ensuring the efficiency and safety of joint use of warning areas. It is most important that the LOA clearly define the conditions, the procedures, and the separation to be applied when a nonparticipating aircraft is transiting the area.


So what, then, does all this mean for daily operations? A number of questions have been asked regarding the status of warning areas and the operating rules that apply to them.

We have seen that warning areas may now exist over both domestic and international waters. The rules that apply to warning areas depend on whether the area lies within domestic or international airspace. Class A and Class E airspace and Part 91 flight rules apply within warning area airspace located between 3 and 12 NM from the coast. However, a military pilot operating in an active warning area in this segment may deviate from Part 91 to the extent that the rules are not compatible with the mission. Section 91.703 incorporates international operating rules for aircraft operations conducted beyond 12 NM from the coast. But, those operating rules only apply to civil aircraft. In a warning area (or other airspace) outside of 12 NM from the coast, military pilots are only subject to the "due regard" provisions of Article 3 of the Chicago Convention.

Thus, may a military pilot operate VFR, above FL 180, in an active warning area within 12 NM from the coast? The answer is "Yes," if mission requirements dictate. Would this violate the requirements for operating in Class A airspace? Answer: "No," again, because the pilot may deviate from the rules if they are incompatible with the mission.

This, then, leads to the question of what separation standards apply to a nonparticipating aircraft while it is transiting a warning area (regardless of whether transit occurs in a segment of the warning area that is within or outside the 12 NM limit). Keeping in mind that the pilot of a participating aircraft operating in a warning area may deviate from Part 91 rules and/or operate under "due regard," as appropriate, the LOA that governs joint use of a warning area becomes a critical element in ensuring a safe operation.

Ordinarily, military activities in an active warning area could be expected to occur without restraint. However, where joint use is agreed to by the FAA and DOD, it may be necessary for the LOA to include provisions for ATC to temporarily impose some restrictions on those activities so that joint use transit of an active warning area can be conducted safely. The methods for achieving this are agreed to by the using and controlling agencies and incorporated into the LOA.

Whenever a nonparticipating IFR aircraft is transiting an active warning area under joint use procedures, it should be afforded approved domestic IFR separation, in accordance with FAAO 7110.65, from all participating aircraft. The using and controlling agencies should include in the LOA whatever provisions are necessary to accomplish this. For example, the LOA could provide for:

- The controlling agency to issue restrictions to the military aircraft that will ensure approved IFR separation is maintained from the nonparticipating traffic.

- The creation of lateral and/or vertical internal subdivisions of the area to facilitate joint use and provide the required separation from warning area activities.

In any case, the LOA should leave no gray areas as to the procedures, conditions, and the separation standards that will be applied while a nonparticipant is in the warning area. Whenever the using agency's mission requirements or other circumstances preclude compliance with the LOA procedures, joint use, obviously, must be terminated until such time as the agreed-upon procedures can be met.

(Note: The above discussion applies to activities conducted in warning areas. In the case of military operations conducted in airspace that is both beyond the 12 NM limit and outside a designated warning area, there are no "joint use" LOA's covering those operations, and the military activity is subject solely to "due regard" provisions.)


Positive action in applying warning area joint use procedures should prevent a recurrence of incidents such as the one described above. Real time joint use of warning areas has been conducted safely for many years. A clear, specific LOA, combined with thorough knowledge of LOA requirements by all concerned, will ensure that joint use remains an effective and safe air traffic management tool.



1. FAA Order 7400.2D, "Procedures for Handling Airspace Matters."
2. FAA Order 7400.9F, "Airspace Designations and Reporting Points."
3. FAA Order 7110.65L, "Air Traffic Control."
4. FAA Order 7610.4.1, "Special Military Operations."
5. DOD Flight Information Publication (FLIP), General Planning, Chapter 6, "International Civil Aviation Organization," and Chapter 7, "Operations and Filings Over the High Seas."
6. Executive Order 10854, "Extension of the Application of the Federal Aviation Act of 1958," November 27, 1959.
7. Advance Notice of Proposed Rulemaking, "Controlled Airspace Designations in International Airspace" (50 FR 30798), July 29, 1985.
8. Presidential Proclamation No. 5928, "Territorial Sea of the United States,"
December 27, 1988.
9. Final Rule, "Applicability of Federal Aviation Regulations in Airspace Overlying the Waters Between 3 and 12 Nautical Miles from the United States Coast" (54 FR 264),
January 4, 1989.
10. Special Federal Aviation Regulation (SFAR) No. 53, "Establishment of Warning Areas in the Airspace Overlying the Waters Between 3 and 12 Nautical Miles from the United States Coast," January 4, 1989.
11. Final Rule, "Airspace Reclassification," (56 FR 65638), December 17, 1991.
12. Final Rule, "Offshore Airspace Reconfiguration," (58 FR 12128), March 2. 1993.
13. Final Rule, "Definitions of Special Use Airspace," (61 FR 2080), January 24, 1996.
14. Title 14, Code of Federal Regulations (CFR), parts 1, 71, and 91.
15. Annex II to the Convention on International Civil Aviation, International
Standards and Recommended Practices, Air Traffic Services. (ATA-400/ATP-130)

Controlled Flight into Terrain (CFIT) Avoidance

(Correction to Previously Published Article)


/*ET/ An error was inadvertently made in ATB 99-3, in the article entitled Controlled Flight Into Terrain (CFIT) Avoidance. On Page 3 of the ATB, the article misstates the procedures outlined in FAA Order 7110.65, paragraph 5-9-1(a) (1), Vectors to Final Approach Course. With the correction highlighted, the paragraph should read as follows:

1. When the reported ceiling is at least 500 feet above the MVA/MIA and the visibility is at least 3 miles, aircraft may be vectored closer than 2 miles outside of the approach gate but no closer than the approach gate.

The entire article with the correction inserted follows:

/*ET/ During the fall of 1997, the Commercial Aviation Safety Team, a combined organization of the Federal Aviation Administration (FAA), National Aeronautics and Space Administration, Air Line Pilots Association, Air Transport Association, and airplane and engine manufacturers dedicated to working together to improve aviation safety, chartered a team to look at CFIT accidents. The team developed strategies and interventions to minimize the occurrence of CFIT. The results were nine project areas; one of them is air traffic control.

The following provides a review of the current handbook paragraphs associated with assisting flight crews with situation awareness, safety alerts, minimum safe altitude alerts, and on-the-job training (OJT).

Facility managers need to emphasize the controller's responsibility to assist the flight crew in situation awareness. FAAO 7110.65, Para 2-1-6, Safety Alert, states: "Issue a safety alert to an aircraft if you are aware the aircraft is in a position/attitude which, in your judgement, places it in unsafe proximity to terrain, obstructions, or other aircraft. Once the pilot informs you action is being taken to resolve the situation, you may discontinue the issuance of further alerts. Do not assume that because someone else has responsibility for the aircraft that the unsafe situation has been observed and the safety alert issued; inform the appropriate controller."

Para 2-1-6a states: "Terrain/Obstruction Alert - Immediately issue/initiate an alert to an aircraft if you are aware the aircraft is at an altitude which, in your judgement, places it in unsafe proximity to terrain/obstructions. Issue the alert as follows:


(identification) LOW ALTITUDE ALERT,


THE (as appropriate) MEA/MVA/MOCA/MIA IN YOUR AREA IS (altitude), ..."

Para 5-1-10, Deviation Advisories, states: "Inform an aircraft when it is observed in a position and on a track which will obviously cause the aircraft to deviate from its protected airspace area. If necessary, assist the aircraft to return to the assigned protected airspace."

The issuance of a safety alert is a first priority. Recognition of situations of unsafe proximity may result from minimum safe altitude warning/E-MSAW/LAAS, Mode C, Conflict/Mode C, intruder alert, or pilot report. Once the alert is issued, it is solely the pilot's prerogative to determine what course of action, if any, will be taken.

With more aircraft equipped with flight management systems, we need to use all available tools to establish aircraft position. Do not fixate on just distance measuring equipment (DME). FAAO 7110.65, Para 2-5-3, NAVAID Fixes, states: "Describe fixes determined by reference to a radial/localizer/azimuth and distance from a very high frequency onmidirectional range (VOR)-DME/VOR collocated with tactical air navigation (TACAN)/TACAN/Instrument Lan-ding System (ILS)-DME or Microwave Landing System (MLS) as follows:

a. When a fix is not named, state the name of the navigational aid followed by a specified radial/localizer/azimuth and state the distance in miles followed by the phrase 'mile fix.'

b. When a fix is charted on a standard instrument departure, standard terminal arrival route, en route chart, or approach plate, state the name of the fix.

c. Use specific terms to describe a fix. Do not use expressions such as 'passing Victor Twelve' or 'passing J Eleven.' "

During the process of reviewing accident data, the need for stabilized vertical guidance approaches became evident. When available and practical, clear aircraft for approaches with vertical guidance (ILS). FAAO 7110.65, Para 4-8-1, Approach Clearance, states: "Clear aircraft for 'standard' or 'special' instrument approach procedures only." Paragraph 4-8-1 goes on to state, "An aircraft conducting an ILS/MLS approach when the glideslope/glidepath is reported out of service shall be advised at the time an approach clearance is issued. Standard Instrument Approach Procedures shall commence at an Initial Approach Fix, or an Intermediate Approach Fix if there is not an Initial Approach Fix. Where adequate radar coverage exists, radar facilities may vector aircraft to the final approach course in accordance with Para 5-9-1, Vectors to Final Approach Course."

Except for vectors for visual approaches, vector arriving aircraft to intercept the final approach course:

a. At least 2 miles outside of the approach gate unless one of the following exists:

1. When the reported ceiling is at least 500 feet above the MVA/MIA and the visibility is at least 3 miles, aircraft may be vectored closer than 2 miles outside of the approach gate but no closer than the approach gate.

2. If specifically requested by the pilot, aircraft may be vectored to intercept the final approach course inside the approach gate but no closer than the final approach fix.

b. For a precision approach, at an altitude not above the glideslope/glidepath or below the minimum glideslope intercept altitude specified on the APC.

c. For a non-precision approach, at an altitude which will allow descent in accordance with the published procedure.

Para 5-9-4c. Approach clearance except when conducting a radar approach. Issue approach clearance only after the aircraft is:

1. Established on a segment of a published route or instrument approach procedure, or

2. Assigned an altitude to maintain until the aircraft is established on a segment of a published route or instrument approach procedure.



In some of the accidents reviewed, OJT was being conducted and may have contributed to the accidents. All OJT instructors are reminded to maintain control and vigilance on the position.

In some cases, non-rated controllers were operating a position unsupervised. FAAO 7220.1, Certification and Rating Procedures, Para 50b, states: "The individual may perform duties as a controller only at those sectors or positions at which they are qualified; otherwise, they are in training under the direct supervision of a controller qualified at the position being worked." (ATP-110)



What do the following scenarios have in common?

Scenario A: Aircraft #1 was northbound level at FL 180. Aircraft #2 was 10 miles north of aircraft #1's position and was southbound, level at FL 190. Aircraft #2 requested lower and the controller issued a descent clearance to aircraft #2. The aircraft passed each other with less than 1-mile lateral and less than 1,000 feet vertical separation.

Scenario B: Aircraft #1's climb was stopped at FL 290 to allow two aircraft at FL 310 to cross its flight path. The first aircraft at FL 310 was issued a climb clearance. After the first aircraft had vacated FL 310, the controller issued aircraft #1 a climb to FL 310. Too late, the controller realized that the second aircraft at FL 310 was in the way, and despite efforts to correct the situation, separation was lost.

The preceding scenarios are representative of a growing number of controller errors attributed to failing to notice what is literally right in front of one's face. That is, the data block is clearly present, yet is ignored or overlooked. This phenomenon seems to stem from a form of 'tunnel vision' coupled with poor scan technique. The end result is poor traffic awareness and, sometimes, a loss of separation.

Tunnel vision is often associated with a controller focusing attention on one particular event to the extent that events taking place in another area of the controller's jurisdiction go unnoticed. Tunnel vision is also involved in situations where the controller is focused on the intended plan of action and the desire to execute the action. In such situations, no notice is taken of other aircraft in the immediate vicinity of the aircraft on which the controller is focused or other aircraft downfield from the aircraft that should be recognized as a separation threat.

Because the traffic picture is constantly changing, each control decision must be based upon information obtained from the aircraft's recent past, present, and future position. The importance of maintaining an accurate picture of the traffic situation cannot be understated. Air traffic control has been described by some as the ultimate video game. However, it is best compared to a game of strategy, such as chess rather than a video game. In many fast moving video games, the picture changes rapidly, but the player reacts to the situation in rapid-fire fashion. Full evaluation of each action is rarely accomplished with this method. If air traffic control is approached in this manner, the results are often identical to the errors discussed in this article.

However, in a game of chess, even though the player must also react to the movement of his/her opponent's chess pieces, there is one clear difference. The chess player's move must be plotted and carefully considered in relation to the other pieces on the board. The effect of the present action as well as its future effect must be taken into consideration in order to gain success in this game. Obviously, chess-like considerations must be made at a far more rapid pace than that of a regulation chess match. The chess-like strategy approach is a significant element in keeping an accurate picture of one's traffic. Competent scanning patterns flow naturally from this approach.

The incidence of mistakes can be reduced if the tools of the trade are also incorporated into the equation. Note pads, flight progress strips, flight data blocks, and the like are excellent methods of storing temporary data or reference information rather than relying completely on short-term memory recall. Before issuing control instructions, check for the consequences. To error or not to error, that is the question. (AAT-200)


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