Air Traffic Bulletin

Issue 99-1 Winter 1998-99

Table of Contents: [Back]
Altimeter Setting
ASOS/ATIS Interface - Closing Message
The Authority for Closing an Airport
US Airways' New Aircraft/Nonprecision Approaches
Visual Separation
    Phraseology Trap

Altimeter Setting

/*F/ There have been instances where pilots who have contacted an AFSS for local airport advisory services have been directed to the local AWOS/ASOS to retrieve the current altimeter setting. FAAO 7110.10, Paragraph 4-4-2b-3a, outlines the information that a controller shall provide the pilot when issuing an airport advisory. Facilities issuing an airport advisory shall provide the current altimeter setting, unless the scheduled air carriers or aircraft operators have requested the omission in writing.

FAAO 7110.10, Paragraph 4-3-5, outlines the information that pilots shall receive during routine radio contacts. If the aircraft is operating below 18,000 feet MSL, issue current altimeter setting obtained from direct reading instruments or received from weather reporting stations. Use the setting for the location nearest the position of the aircraft.

Aircraft arriving or departing from a non-towered airport which has a commissioned ASOS/AWOS, with ground-to-air capability shall be advised to monitor the ASOS/AWOS frequency for the current altimeter. This requirement is deleted if the pilot states, on initial contact, that he/she has the automated weather.

Controllers are responsible for following these procedures and should review these paragraphs as appropriate. (ATO-300)

ASOS/ATIS Interface - Closing Message

/*T/ (Part-time locations with ATIS and ASOS only) Edition 98-6 of the Air Traffic Bulletin, dated Fall 1998, contained an article by ARW-200 which explained the ASOS/ATIS interface. The DME Corporation has delivered to the FAA the first 25 interface units for installation and will deliver 50 units each month until all part-time ASOS/ATIS equipped facilities have the interface.

During the procedures evaluation phase, evaluation facilities were asked to record a new closing message each evening when the facility closed and cancel the message when the facility reopened. Air Traffic has determined that the closing message is static information and may be left on the 90-second ASOS remarks window until any part of the information changes. A pilot calling the ASOS phone line during the day will hear the static closing message but it will not be broadcast until the facility closes. This will simplify the closing ATIS requirement to activating the interface and ensuring that the ASOS is in the 1-minute observation mode. (ATO-120)

The Authority for Closing an Airport

/*TE/ Customer feedback received by one of our regional offices concerned the use of the word "closed" with regard to an airport when the airport was not actually closed, but may have been below approach minimums or had implemented ground holds due to weather or traffic saturation in the area. It is important to remember that ATC personnel do not have the authority to determine if an airport is closed or not. Controllers should not issue any control instructions implying the airport is closed unless the appropriate airport authority has declared the airport closed. (ATO-120)

US Airways' New Aircraft/Nonprecision Approaches

/*TE/ US Airways (USA) has made a significant corporate commitment to purchase approximately 400 Airbus aircraft over the next several years. The new A-319/320/321/330 aircraft will be delivered with the latest flight management system (FMS) and navigational technologies. The elimination of nonprecision approaches was the number one priority from the operations panel during the Secretary of Transportation's Safety Summit held in New Orleans in December 1995. USA has made an operational decision that the new Airbus aircraft will not fly nonprecision approaches and they have received operations specifications approval to conduct three dimensional (3D) RNAV approaches to every runway serviced by an ILS, localizer only, and back course approach. It is important that we in Air Traffic be supportive of USA's efforts to take advantage of the technology they are purchasing with the A320 fleet.

The program is virtually transparent and, in effect, mirrors Phase 3 of the GPS overlay program except that the standard instrument approach procedures being overlaid are to be used as specials by USA's Airbus aircraft instead of public use. The four conditions where USA pilots will request clearance for the RNAV approach are: (1) the ILS is out, (2) the glideslope is out, (3) the runway in use is serviced by a localizer only or a back course approach, or (4) for validation, demonstration, or proficiency purposes. It is important to note that the flight crew will always initiate the request and our controllers will simply respond to the pilot's request for a special in accordance with FAAO 7110.65, paragraph 4-8-1. USA has furnished our facilities (CLT, PHL, RDU, SEA, and TPA) at the first five primary airports with copies of the special instrument approach procedures and the program officially began February 1.

At our request, USA has developed a video outlining the program from a controller's perspective. Distribution will be to each of the regional operations branches, each terminal facility where the aircraft will operate either as a primary airport or as a weather alternate, and the ARTCC's servicing those airports. (ATO-120)

Visual Separation

/*E/ The use of visual separation in the en route environment has evolved over the last several years. It is now possible to use this tool in several different ways. It can be used to separate aircraft on visual approaches and to separate passing aircraft on opposite courses; however, the majority of controllers use the tool that allows separation in the en route phase, below flight level (FL) 180.

Several recent incidents and errors in the system involve the misapplication of visual separation rules. This bulletin will reiterate the rules of visual separation in the en route environment below FL 180. It is important to note that no changes have been made, this is only a review of current procedures. FAAO 7110.65, Air Traffic Control, paragraph 7-2-1, VISUAL SEPARATION, states:

"Aircraft may be separated by visual means, as provided in this paragraph, when other approved separation is assured before and after the application of visual separation. To ensure that other separation will exist, consider aircraft performance, wake turbulence, closure rate, routes of flight, and known weather conditions. Reported weather conditions must allow the aircraft to remain within sight until other separation exists. Do not apply visual separation between successive departures when departure routes and/or aircraft performance preclude maintaining separation."

FAAO 7110.65 further covers the use of visual separation in the en route area. Paragraph 7-2-lb, EN ROUTE, states:

"You may use visual separation in conjunction with visual approach procedures. Visual separation may also be used up to but not including FL 180 when the following conditions are met:

1. Direct communication is maintained with one of the aircraft involved and there is an ability to communicate with the other.

2. A pilot sees another aircraft and is instructed to maintain visual separation from it as follows:

(a) Tell the pilot about the other aircraft including position, direction, and unless it is obvious, the other aircraft's intentions.

(b) Obtain acknowledgment from the pilot that the other aircraft is in sight.

(c) Instruct the pilot to maintain visual separation from that aircraft.

(d) Advise the pilot if the radar targets appear likely to converge.

(e) If the aircraft are on converging courses, inform the other aircraft of the traffic and that visual separation is being applied.

(f) Advise the pilots if either aircraft is a heavy.

(g) Traffic advisories and wake turbulence cautionary advisories shall be issued in accordance with para 2-1-20, WAKE TURBULENCE CAUTIONARY ADVISORIES, and para 2-1-21, TRAFFIC ADVISORIES."

Please pay special attention to the lines above in bold face, "Visual separation may also be used up to but not including FL 180..." Several of the incidents mentioned have been due to the fact that controllers are not ensuring this portion of the procedure.

It is suggested that specialists review these paragraphs from time to time. Think about the most common instances in which you use visual separation. Review your methods and procedures and ensure that they are in conformance with FAAO 7110.65. Also, remember no changes have been made; this is just a refresher on visual separation procedures. (ATO-110)


The primary purpose of the ATC system is to prevent a collision between aircraft operating in the system and to organize and expedite the flow of traffic.

The provision of additional services is not optional on the part of the controller, but rather is required when the work situation permits.

Give first priority to separating aircraft and issuing safety alerts as required in this (7110.65) order.

Those three statements sum up the heart and soul of air traffic control. When I was a developmental, my instructors would point out that there are requirements which must be met that are contained in FAAO 7110.65. There were also requirements that were of "moral responsibility" and not specifically written down anywhere. The old-timers valued both responsibilities equally and took great pride in their ability to provide superlative service to all who operated in their areas of jurisdiction. For example, if an aircraft called ready for taxi from a non-movement area, the pilot would be informed of any known hazards, such as other traffic observed or known to be moving in the area, or of what appeared to be a pothole in the taxi street.

What the old-timers called "moral responsibility" really was "additional service." For the most part, the newer folks are doing the same thing; providing first-rate service, but every once in a while, someone fails for one reason or another to provide some simple information which could make the difference between an incident or a smooth operation. It gets back to breaking links in the error or accident chain.

Recently, two aircraft collided at night on a taxiway. If the controller had warned either one of the pilots that another aircraft was operating in the vicinity, it is possible that a link in the accident chain could have been broken and the collision avoided. The controller had information that neither pilot had, but the controller chose not to provide that additional service. What a shame! Should the pilots have been more vigilant? Absolutely! But that is not the point. The point is that information could have and should have been shared, but wasn't.

FAAO 7110.65 is quite specific regarding separation standards for aircraft on final approach to the runway, runways themselves, and during the en route phase of flight. There are no standards of separation to be applied to nonmovement areas or taxiways. So, if aircraft collide in the traffic pattern or on ramp or taxiway surfaces, is it a controller's fault? No, but remember the first sentence in 7110.65 Chapter 2, paragraph 2-1-1 ATC SERVICE? "The primary purpose of the ATC system is to prevent a collision between aircraft operating in the system and to organize and expedite the flow of traffic." Does this mean that controllers are expected to provide separation services to aircraft on nonmovement areas? No, it does not. What it means is this; you have the big picture for the most part. Your workstation is on an elevated platform with panoramic windows giving you the opportunity to see possible hazards which those at ground level may not be able to see in time to prevent an incident.

The pilot is required to avoid mishaps by using the "see and avoid" method whether on the ground or in the air. You can facilitate by sharing information. That action will satisfy the responsibilities required of you by FAAO 7110.65. So whether you call it "additional services" or an unwritten "moral responsibility," make the effort to share information that may be helpful to the pilot. Break a link!     

Phraseology Trap

Is the failure to use standard phraseology a nitpicky item? The use of nonstandard phraseology can be a subtle trap for you. Here is how one ATCS got caught in the trap and received an operational deviation for his trouble.

ATCS A: "Hey Motle, Ripper on the 05."
ATCS B: "Yeah."
ATCS A: "Can you take him at FL330 or should I leave him at FL310?"
ATCS B: "I can't take him at FL330."
ATCS A: "Okay, BB."
ATCS A thought that controller B said, "I can take him at FL330." If you think about it, you can see that it would be very easy to misunderstand whether the controller said "can" or "can't." If standard phraseology had been used, would the misunderstanding have occurred? Compare the following conversation with the first example.
ATCS A: "Motle, Ripper on the 05, APREQ."
ATCS B: "Motle."
ATCS A: "Will you accept NWA 465 climbing to FL330 or FL310?"
ATCS B: "Unable NWA 465 at FL330, maintain FL310."
ATCS A: "NWA 465 at FL310, BB."


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