The Air Traffic Controller Perspective

INTRODUCTION

ASAP #22399 Event Narrative

[DATE]. [CALLSIGN], [TAIL #], [WING] assigned C-17 operating local training sortie departing [LOCATION], destination Sabre AAF [Army Airfield]. at FL230 approaching waypoint NEGEE [point along an established military training route], aircrew requested pilot’s discretion unlimited descent to Minimum Vectoring Altitude [MVA]. The sortie is being conducted in accordance with Integrated Mission Sortie [IMS] training requirements which place additional emphasis on tactical employment. The unrestricted descent accommodates exercise of tactical penetration descent capabilities. Aircrew received clearance to descend, however significant traffic in the vicinity resulted in an amended clearance to level off at 11,000 feet. The crew deconfigured from tactical descent configuration and, as the descent rate decreased, received a TCAS RA [Traffic Collision Avoidance System Resolution Advisory] due to aircraft passing at 10,000 feet. Visual contact was maintained with the other aircraft, clearance was maintained, and a subsequent descent to 10,000 MSL [mean sea level] was directed once traffic was clear. The PF [pilot flying] disconnected the autothrottles for the tactical descent, and once the aircraft leveled at 10,000 feet, did not recognize that throttles were at idle and airspeed was bleeding off. PF recognized the thrust deficient condition as the aircraft entered ALPHA mode which lowers the nose to maintain airspeed and prevent entering a stall condition at the expense of altitude. The PF added power to regain airspeed but descended to approximately 9,600 feet. ATC [air traffic control] queried the crew, we acknowledged the deviation and responded that we were promptly returning to our assigned altitude of 10,000 feet. The altitude deviation occurred as a result of the PF failure to recognize thrust deficient condition and correct prior to altitude deviation. Causal factors include task saturation and loss of SA [situational awareness]. This was precipitated by a TCAS RA, and unexpected deconfiguration from rapid descent. The altitude deviation was promptly recognized and corrected.

ASAP #22399 Submitter’s Suggestions

I do not believe ATC was fully aware of what we were planning to do and there was a number of other aircraft operating in the vicinity which presented a conflict to our intended flight path. Prior coordination with ATC to ensure clear understanding of our capabilities and intent could have prevented the conflict. We may need to alter our flight plan route to remain clear of other air traffic. We may need to perform a cruise descent which is more conducive to IFR [instrument flight rules] operations. Either way, we should have a clear understanding between ATC and crews that we are transitioning from the enroute structure to low-level.

When investigating this Aviation Safety Action Program (ASAP), I learned that ATC did not fully comprehend the C-17’s rapid tactical descent profile. The C-17’s descent rate astounded Federal Aviation Administration (FAA) controllers. Although the crew did receive clearance for the descent, ATC did not anticipate how fast the crew would descend; thus, ATC subsequently amended the clearance to 11,000 feet due to traffic that was not originally anticipated to be a factor. Additionally, analysis of the event also revealed that traffic was a factor in the ATC sector in which the event occurred. Although ATC was trying to accommodate the crew’s requested clearance, ATC was also trying to deconflict the C-17’s descent profile with other traffic in the area.

After reviewing the event, I concluded the ASAP submitter’s suggestions were accurate: “I do not believe ATC was fully aware of what we were planning to do … Prior coordination with ATC to ensure clear understanding of our capabilities and intent could have prevented the conflict.†Later, in an email exchange with the ASAP submitter, the pilot went on to say:

Due to growing emphasis on tactical training, we are starting to fly in unfamiliar airspace. It is worth noting the entry point for this particular MTR [military training route] is only 14 miles from [Airfield]’s Class C airspace. Our pre-mission planning failed to consider the impact of our tactical descent on arriving and departing aircraft … I have had great success reaching out directly to the ATC facility and coordinating in advance what we wish to do. I have yet to encounter a facility unwilling to work out some way to facilitate our request and that direct coordination really goes a long way. Most importantly, ensuring a clear understanding on both the crew and controller’s part of what precisely is going to happen.

Around the same time that I was working on this ASAP analysis, our military ATC experts in Air Mobility Command’s (AMC) A3AP, ATC Ops & Procedures Branch, were collaborating with military ATC controllers at the wing level, analyzing a TCAS RA event reported via another ASAP. As part of their recommended actions, the military controllers invited the military pilot involved in the TCAS RA event to visit their local Radar Approach Control (RAPCON) to provide a pilot perspective, while witnessing the ATC challenges of working with the numerous visual flight rules (VFR) of aircraft within their airspace.

Our ATC experts and ASAP #22399 highlighted a vital lesson for all pilots: We do not always understand and appreciate the ATC perspective. Despite working together daily and sharing standardized procedures and communications, we (pilots) frequently do not analyze events through the view of the ATC controller.

The A3TO, Op RAMS Branch, and A3AP, ATC Ops & Procedures Branch, decided to collaborate on an article to share the ATC perspective with pilots. We asked several military ATC controllers to share their perspective via the following question: If a pilot visited your ATC facility for the day and you had an opportunity to share information, what topics would you emphasize with them?

SMSgt Joe Southern, HQ AMC Operations and Procedures, Scott AFB, IL, MSgt Cory Kimmel, Air Traffic Controller from the 305th Operations Support Squadron (OSS) at Joint Base McGuire-Dix-Lakehurst (JBMDL), NJ, and MSgt Casey Lee, Air Traffic Controller from the 60 OSS at Travis AFB, CA, volunteered to share their years of air traffic expertise by emphasizing key topics that will help pilots understand Air Traffic Controller Perspective. Southern, Kimmel, and Lee have a wealth of air traffic control experience, working in various air traffic control facilities, including Tower and RAPCON. They have also served in leadership positions, including Watch Supervisor, Chief Controller and Assistant, and Major Command Staff. Additionally, they have a depth of expertise serving as Noncommissioned Officers in Charge of Training, Standardization and Evaluation, and controlling, leading, and liaising down-range alongside Host Nation and in contingency environments.

ATC PERSPECTIVE BY SMSGT SOUTHERN, MSGT KIMMEL, AND MSGT LEE

Understanding ATC’s responsibility for separation of aircraft: The purpose of the ATC system is to provide a safe, standardized, and efficient flow of air traffic. As part of the ATC system, a controller’s primary responsibility is to ensure the safe separation of aircraft. Our primary responsibility is simple in premise but complex in execution. As you know from being a pilot, flight procedures are standardized, but the procedures are vast, and execution of those procedures can vary greatly depending on the situation, location, and conditions.

When it comes to ATC’s responsibility for separation of aircraft, airspace classification (operation location) and type of clearance (IFR or VFR) the flight is operating generally determine separation criteria. The separation criterion that pilots most often misunderstand is the ATC separation of VFR traffic in Class Echo airspace. In Class Echo airspace, there is no set separation standard between IFR and VFR traffic. In accordance with the FAA’s JO 7110.65Z, Air Traffic Control procedures, paragraphs 5-1-4 and 7-6-1, only traffic calls and safety alerts are required unless a pilot requests a vector. As defined by See and Avoid, throughout the AIM and JO 7110.65, verbiage states that the pilot is still responsible for the aircraft. Note 2 in the definition of “Traffic Advisories†in both regulations spells this out. This note is important as traffic advisories are conditional based on the controller’s higher priority duties and controller workload. For example, when a VFR aircraft is less than 500 feet vertical separation, targets are likely to merge, and traffic advisories have been made; the controller bears no responsibility. However, many controllers believe there is an ethical responsibility in these situations in which the controller, although not required, will take action to ensure the safety of flight of all within their control. This regulatory guidance and controller perspective comes into play when non-participating VFR traffic operating Class E comes into conflict with traffic we are controlling. We want to emphasize that traffic separation, especially in VFR conditions, is a shared responsibility between the controller and pilot. Although controllers try to maintain a safe separation between traffic, the controller will have limited options in certain situations, especially if the VFR traffic is not in radio contact and legally flying in Class E airspace.

We will come back to the topic of separation when we discuss TCAS RAs. Before we discuss TCAS RA events, local area airspace and traffic congestion are two important topics that provide context.

Local Airspace: From a controller’s perspective, local airspace (home airfield) is an important issue for several reasons. First, as you know, the local airspace is influenced by a multitude of factors, such as environmental (prevailing winds) and geographical features (terrain and obstacles). Furthermore, our ATC procedures are heavily influenced by the local airspace, such as special use airspace, satellite airports in the immediate vicinity, and departure and arrival corridors of adjoining airspace. For example, Travis AFB is “sandwiched†between San Francisco’s Class Bravo airspace to the south and Sacramento’s Class Charlie airspace to the Northeast. There are two airports that have operational control towers in our airspace and multiple satellite airports. Additionally, we have Napa County Airport to our immediate west. Travis’ airspace essentially is a channel for aircraft flying between the two airspaces and creates a lot of overflight and VFR traffic. Likewise, JBMDL’s airspace bumps against Philadelphia’s Class B airspace, which influences how VFR traffic transits around JBMDL’s airspace. Additionally, when active, Restricted Area 5001 constricts our ATC operations as well. All that being said, a lot of traffic transits the airspace that is unpredictable and varies every day.

VFR traffic within the vicinity of airfield: As you know from flying, VFR traffic can be a “wildcard.†VFR traffic congestion can be seasonal, like in Elmendorf AFB, AK, during the summer, or it can simply be a beautiful day for flying that brings out the VFR pilots.

VFR traffic creates conflicts and increases the controller’s workload. It could also lead to departure delays due to unidentified targets flying across the departure end (outside of Class Delta airspace). We do not launch an aircraft into a conflict; thus, we will issue delays while on the ground. Additionally, aircraft inbound to the airport will often be given extended vectors or box patterns due to aircraft flying across final approach courses and orbiting in the same area that aircraft would be turned to final. Lastly, VFR traffic also leads to additional coordination with adjacent agencies in the event that aircraft will enter their airspace. If we are in com­munication with these VFR aircraft, then we are able to vector and assign altitude ranges to have positive control to prevent conflicts from occurring.

From an ATC perspective, VFR traffic can also be a “wildcard†on whether a VFR pilot communicates with us. Pilots do not understand how many aircraft operate that are not in communication with ATC. Possibly due to newer technology that allows VFR pilots to navigate without ATC assistance, a lot of traffic tends to never speak to us. They often push the limit of when they are required to speak to us, i.e., flying just above or around Class D airspace, which creates conflict with our local flying operations. This situation becomes even more challenging during tactical operations, when military aircraft are rapidly maneuvering in and out of Class Delta and Echo airspace. In these cases, VFR traffic skirting the boundaries of Class Delta can quickly become a traffic conflict with the military aircraft performing these tactical profiles.

ASAP # 20415, which was a traffic conflict at Travis AFB, is a good example of how VFR traffic can skirt Class D airspace without communication and create a challenging situation for both the controllers and aircrew. In this ASAP, a KC-10 crew was conducting an approach to Runway 21L with a planned missed approach and were instructed to fly runway heading to 5,000 feet. An unidentified target, to which neither the Tower nor the RAPCON was speaking, crossed west to east at approximately 3,000 feet. The KC-10 crew planned a missed approach and started a rapid climb around 200 feet MSL. The control tower issued a new altitude assignment of 2,000 feet, referencing the unidentified target flying at an unverified altitude of 3,000 feet and just off departure end. From the report, the traffic appeared on TCAS and then was visually acquired. Due to the rapid climb, the KC-10 had to conduct a reversal of flightpath and descend back to 2,000 feet. An RA never occurred.

Understanding TCAS RA events in the local area pattern: When pilots step back and look at the local airspace and its constraints, VFR traffic (especially during peak congestion and without communication with ATC services) and flight procedures, they gain a better understanding of the controller perspective. First, VFR traffic can be unpredictable. Pilots can legally fly VFR in Class Echo airspace without communication with ATC provided they do not enter another class of controlled airspace (Classes A, B, C, or D) without ATC clearance. Without communication with VFR traffic, a challenging situation can occur for us and the flights we control to maintain separation from traffic. Thus, there will be events in which controllers have done their absolute best to separate verified VFR aircraft from all others by no less than 500 feet vertically, and a TCAS RA could still occur.

ASAP #23124 is a good example that highlights this case. ATC analysis of this event showed that the arrival controller had attempted to contact the VFR traffic multiple times, with no success, and had given the C-32 several traffic advisory calls. The arrival controller then asked the C-32 if they would like to discontinue the approach, which they accepted. The controller provided the C-32 with traffic advisory calls for another VFR traffic, with which the controller was in communication. Bottom line: The controller maintained positive control, provided traffic advisories to the C-32 and the one participating VFR traffic, and maintained separation of traffic (laterally and vertically).

Finally, TCAS is a great safety system that requires a pilot to respond to RAs; however, keep in mind that a TCAS RA does not necessarily mean that ATC separation standards were compromised. As ASAP #23124 shows, when traffic is issued—to an IFR aircraft on a VFR target—and called “in-sight,†a controller is not taking any actions unless requested. TCAS could still issue a RA. The controller does not know the limits and thresholds of the TCAS system. Additionally, FAA’s JO 7110.65Z, Air Traffic Control procedures, paragraph 2-1-28 TCAS Resolution Advisories is clear that controllers will not issue control instructions contrary to the RA procedure. A controller does not know what instructions the RA is giving unless the pilot relays the information. After a pilot responds to an RA and approved separation is reestablished, the controller regains responsibility for separation.

Communication—an area that can always be improved for both controllers and pilots: As controllers, we need to be aware that we are providing a service and part of that is ensuring pilots fully understand our expectations and control instructions. We need to be clear and concise and help “paint the picture†for pilots. Conversely, if we have not done this well enough or if there is any confusion, pilots need to be sure to ask questions and clarify instructions. For both controllers and pilots alike, effective communication starts with using standardized terminology and protocols.

First, controllers and pilots must be on the same page when discussing intentions and painting the picture for both parties. When making a request with us, pilots should communicate any non-standard information that will alter the flight profile or performance of the aircraft so that we can anticipate how it might affect the clearance.

For example, in ASAP #20486, the pilot did not mention to the controller that they wanted to practice an engine fail scenario. To provide a safe and efficient flow of traffic, controllers need to anticipate pilot actions based on aircraft characteristics, which is emphasized during training. From a controller’s perspective, practicing an engine fail scenario in the VFR downwind leg should not be a usual occurrence. Unless told otherwise, we expect to be able to turn, climb, or extend an aircraft without too much delay, especially in the fast moving and changing tower environment. Thus, when you review the ATC response to ASAP #20486, you see:

Also of note: KIAB was unaware that [CALL SIGN] required an upwind extension for the engine fail scenario. ATC is giving instructions based off of anticipated actions (i.e., normal patterns and rates of climbs/turns). If aircrews communicate the need for upwind/downwind extensions, etc., controllers can provide better services.

When information that affects future possible actions are withheld, it is difficult to keep options open when other things do not go as planned. Transparent communication in this aspect comes down to painting the picture for both controller and pilots so there is no question of either’s intentions or limitations.

The second part of transparent communication has to do with getting to know each other’s perspectives. Constructive and meaningful dialogue helps build a professional relationship between controllers and pilots. Constructive feedback is important to a safe and efficient flying environment.

The ASAP program and Hazardous Air Traffic Report (HATR) reports are great safety tools for identifying safety issues at the Major Command and wing levels.

If available, the ASAP report can be maximized by reaching out to the facility’s leadership to discuss what went wrong as the ASAP is being worked. There are multiple ways to connect with your local ATC service to offer feedback and build a relationship:

1. Contact your local Airfield Operations Flight Commander or OSS leadership.
   • Timely feedback is always best. As soon as possible after an event, please contact them via email.
   • Be as specific as possible about the date and time of the event.
   • Offer a brief overview of what transpired.
   • Identify the specific issue that you are addressing.
   • Leave emotion, frustration, or anger out of the discussion. Emotion does not help solve issues; facts do.
   • Note: Constructive feedback does not have to be negative. Constructive feedback can be as simple as providing positive comments or a “thank you†when the facility provides exceptional service. Positive feedback reinforces good behaviors in everyone. Please take the time to offer positive and negative constructive feedback when warranted.
2. Pilot and Controller Liaison program (or similar local wing programs): Every base should have a robust Pilot and Controller Liaison program. The purpose of the program is to create a forum to address specific issues and foster growth and learning by both professions. More importantly, the program is an opportunity to help build communication, trust, and professional relationships between controller and pilot.

Both controllers and pilots are equally committed to the safety of flight operations; thus, learning from each other’s perspectives is imperative. Whether it was human error or a failed process, usually a transparent conversation between the parties can keep the situation from happening again.

CONTROLLER TRAINING

We have seen a few ASAPs expressing concerns regarding controllers in training. Training is an important topic for any profession with complex procedures that require a high degree of technical expertise. Just like pilots, training is a constant evolution for controllers. Even after earning our first facility rating and upgrading to 5-level within our Air Force Specialty Code, a U.S. Air Force controller is constantly in training. Whether training for the next qualification, learning new local area procedures after moving to a new airfield, or simply maintaining skill proficiency, training is a necessity to build and maintain a skilled controller profession.

An essential piece of the training is actual hands-on experience. Inexperienced controllers need that real time experience, so they learn how to apply procedures in a demanding environment. A critical tenet at the very beginning of JO 7110.65 states, “Controllers are required to be familiar with the provisions of this order that pertain to their operational responsibilities and to exercise their best judgment if they encounter situations not covered by it.†The more experience a controller has, the better their judgement, and the safer the skies.

There will be times when there is some fumbling around on the radio transmission or you hear that second voice boom in with a “disregard.†Realize that there are times when training is in progress when you are flying and interacting with a new controller. Just like aviators, sometimes the best training is those self-critiquing moments when a new controller makes an error, and the trainer is allowing a trainee an opportunity to see the error and correct it. The trainer will allow latitude while providing oversight to ensure that safety is maintained. A good example of this training perspective is the formal response (Action Taken Section) to ASAP #23306. The Airfield Operations Flight Commander provided an assessment of the event, in which a new controller was learning:

The ground controller in position at that time has been in ground control all of 3 weeks. If it sounds like the controller is reading from a script during this occasion, the individual is still learning and gaining the ability to listen to the full request before they start thinking about what they are going to say over the radio. In terms of the delayed response time, trainees tend to hesitate before making a transmission. Regarding the taxi instructions as referenced at the beginning of the ASAP report, ground controller gave back correct taxi instructions. The pilot read back incorrectly, and Ground said affirmative. Before the next transmission from the pilot to ask for clarification (less than 5 seconds) the trainer was pointing out a mistake and then was going to prompt the trainee to fix his mistake … Listening to the tapes I believe that there is no safety of flight issue. No one was flying or moving on the airfield. That was the only flight operation at that time. Before the aircraft even moved the miscommunication was resolved.

CONTINUING THE DISCUSSION

We covered many topics in this article, but we are only scratching the surface. The biggest takeaway from this article is keeping the conversation going. We encourage both controllers and pilots to connect at the local level to discuss events when they occur, provide professional and constructive feedback, and create a dialogue on local area procedures. Discussion creates an opportunity to share and understand perspectives, discuss procedures, provide meaningful feedback, and ultimately promotes growth in our professions. We share a common perspective—safety—thus, we should continue this discussion.