Cognitive Systems Engineering Laboratory

Institute for Ergonomics

The Ohio State University

Due to the configuration complexity of the taxiways and runways found on the surface of JFK, there is a significant opportunity to improve performance with a surface management system. Such a system could increase capacity and efficiency by supporting:

• Improved situation awareness about the current and future state of surface traffic and constraints
• Collaboration between the various airport operators (carriers, Port Authority and FAA)
• Development of greater shared understanding of the priorities, duties and constraints of the different operators
• Reasoning (computations) to help identify and evaluate alternative plans to deal with constraints within this highly complex and dynamic environment.

It should be noted that a contributor to this complexity is the fact that this is not a hub airport dominated by a single carrier. Rather JFK serves a large number of airlines, many of which file significant numbers of flights into and out of JFK, making planning and real-time adjustments even more challenging.

Below we present two detailed scenarios, along with a discussion of the general classes of situations where SMS could be of value. The first scenario presented below focuses on two serious potentials for conflict within the jurisdiction of one of the major operators at JFK - Airline X:

• Departing and arriving aircraft
• Early arrival of aircraft

Scenario Context: Before identifying scenarios that we know could benefit significantly from a system such as SMS, we will first present a case which serves to illustrate the constraints with which airport operators must deal with in order to provide safe and efficient surface movement operations every day.

In this example, a significant constraint on the system is the configuration of the airport due to summer weather. In the summer, as a result of the normal prevailing winds, JFK is often in the 13 configuration. Though both 13L and 13R are suitable for arrival and departure traffic, optimally 13R (14,500 ft) is used as the main Departure Runway and 13L (10,000 ft ) becomes the main Arrival Runway, though 13L is often used for northeast departures except for heavier (Europe-bound) aircraft.

In this configuration, conflicts between departing and arriving aircraft can often occur within the taxiway intersections, or throats, of Airline X-controlled surface space. Airline X controls only 3 such throats – MA, LA and KK – in which to direct both arrivals and departures (see figure 2a). Airline X can, however, request permission for specific flights to use K and H. (see figure 2b)

Additionally, more than _ of the gates located in Terminal 3, Gates 1 – 8, are accessible only through KK and Gates 9 and 10 via LL. Due to the configuration of surface space surrounding Terminal 3, aircraft do not have enough space to navigate around Terminal 3 in order to gain access to the west side of Terminal 3 or Terminal 2 and only a single aircraft may traverse the surface area between these terminals at any given time. (See figure 1)

Conflicts frequently occur between inbound aircraft approaching the terminal that are still within ATC controlled surface space (taxiways A and B, for example), and departing aircraft that are still within the boundaries of airline controlled surface space. The ATC and airline staff controlling aircraft movement in these areas sometimes have little or no prior knowledge of the intent of the other party in regard to the surface movement of aircraft, making coordination difficult. Additionally, surface conflicts can be caused by the early arrival of an aircraft. Gate availability issues also can arise following the early arrival of any aircraft.

For arriving aircraft this scenario begins approximately 20-miles out when Approach Control at the TRACON (Terminal Radar Approach Control) contacts the flight crew and gives instructions to contact Local Control - usually at the Outer Marker located approximately 5 miles out from the airport. At some point prior to reaching the Outer Marker, the airline In-Range Call Coordinator will contact the arriving flight and supply the flight crew with gate assignment information and, in some cases, runway/weather conditions and NOTAMs. In the case of some carriers/airports, the airline In-Range Call Coordinator is aware of the aircraft through data obtained by a leased system called PASSUR, a system that displays aircraft tracking and associated data tags. (PASSUR also displays the arrival sequence on final to the runway threshold but contains no surface data). In other cases, the Coordinator will monitor ATC to aircraft communications to identify flight position.

As noted above, somewhere in the vicinity of the Outer Marker, Local Control will provide the flight crew with final approach instructions. Once the aircraft is on the ground ATC Ground Control will contact the pilot to obtain gate assignment information and will provide taxiway direction toward the terminal containing the assigned gate (although, in some cases, the pilot will contact ATC Ground Control first). ATC will not direct the aircraft all the way to its gate. Instead, the aircraft will follow ATC taxiing directions until they reach a predetermined position referred to as a "spot", a boundary in which surface control is handed over to the airline (See figure 3). At this point, the pilot will wait to receive instructions from the airline Gate Coordinator who will then direct the aircraft to its assigned gate. Many of these arrival procedures can vary significantly between both airlines and airports.

For out-bound aircraft, push-back procedures begin when the Master Gate Coordinator gives instructions to embark. The aircraft is then instructed by the airline Gate Coordinator to proceed to one of the throats (intersections that lead to the major taxiways). It is within the throats that control is handed over to ATC, who will then provide the aircraft with taxiway directions appropriate to its departure runway.

Within the boundaries of Airline X surface space there may be multiple aircraft in a variety of positions and conditions:

• Aircraft parked at gates – including newly arrived aircraft, flights that will soon be departing and flights in a variety of stages of maintenance and preparatory procedures
• Aircraft that have already pushed back from their gate (per instruction from the Master Gate Coordinator) but that are still in close vicinity of the terminal within Airline X "property" and are awaiting taxiing instructions from the Gate Coordinator
• Arriving aircraft located within the "property" of Airline X that are trying to reach their assigned gate

All three of these categories of aircraft will be within the control of the Airline X Operations Coordinators while located within Airline X’s "property".

The following is an example of a scenario that, though complex, can typically be dealt with successfully through informal communication channels and the experience of the operators. Though SMS could certainly prove to be helpful and could increase efficiency, operators generally handle the situation adequately with current resources.

Airline X has a 747 (Aircraft 1) - an overseas flight from London, England - arriving on 13L. This flight has arrived approximately 30 minutes ahead of schedule due to winds at altitude. This aircraft will be directed to taxi off the runway at ZA, cross at F to proceed down A and to enter into terminal space through throat KK in order to reach its final Gate 4 destination. Once in KK, surface control will be passed over to the airline’s Coordination Center. The aircraft must stop and wait to receive instruction from the airline Gate Coordinator. Part of the conflict here lies in gate availability as the premature Aircraft 1 is assigned to Gate 4, which is currently occupied by a departing Airline Y flight - a flight that, presumably, would have been gone by Aircraft 1’s original Scheduled In-Time. Obviously, Airline Y’s aircraft will have to push-back before Aircraft 1 can park at Gate 4. However, Aircraft 2 (Gate 6) and Aircraft 3 (Gate 8) were scheduled to push-back before the Airline Y flight and if this flight is pushed back to accommodate Aircraft 1 then Aircraft 2 and 3 will have to be delayed.

Figure 1: Airline X at JFK - Terminals 2 and 3, Gates 1 – 29

Aircraft 2 is parked at Gate 6, is departing to Bangor, and is therefore going to be departing on runway 13L - a common departure runway for flights heading to the NE. The plan was to have Aircraft 2 directed by the Master Gate Coordinator to proceed to KK to await instructions from ATC Ground Controller. However, the early arrival of Aircraft 1 through the only Airline X controlled throat with access to this Gate area - KK - will potentially cause a delay in Aircraft 2’s push-back. And since Aircraft 1 will be forced to wait for its assigned gate to be vacated by the Airline Y aircraft, this will result in an even longer departure delay for Aircraft 2.

Aircraft 3, a 767 parked at Gate 8, is a departing flight bound for Paris. The plan was to push-back this flight and have it follow Aircraft 2 out KK. However, as noted above, this flight will also be delayed due to the arrival of Aircraft 1. Finally, taxiway A is still obstructed by Aircraft 4 and 5 awaiting access to LA.

Solution: Possible solutions to this scenario that include Aircraft 1 - 3 involve recognizing conflicts before they occur. The tradeoff is whether to maintain the schedules of Aircraft 2 and Aircraft 3 by delaying Aircraft 1. This delay would be accomplished by directing Aircraft 1 to wait somewhere within the vicinity of Terminals 3 and 4. However, this is an area that is most likely already congested, which would potentially create further conflicts. Alternatively, the Master Gate Coordinator could attempt to identify another available (and appropriate) gate on the east side of Terminal 3 (the gate must be located east of Terminal 3 as Aircraft 1 is already within KK and does not have the space to navigate west around Terminal 3 in order to reach any other gate). This action would potentially involve redirecting appropriate staff to the reassigned gate, coordinating with IAT for the use of one of their gates located in Terminal 4 and, finally, redirecting the aircraft – all of which takes time. Additionally, if the aircraft is also scheduled as a departing flight (i.e., will be picking up passengers and departing again) then this process would also have to include either notifying passengers of the gate change or, alternatively, later ferrying the aircraft to its original gate (assuming that it is still available).

With advanced warning, the gate assignment conflicts, taxiway conflicts and arrival/departure conflicts caused by the early arrival of such an aircraft could be avoided. Additionally, through surface activity displays, congested space - for example the space surrounding the east side of Terminal 3 in the above scenario - could be identified and if necessary, avoided. Gate reassignment to avoid conflict is a solution. As an example, with advance warning Aircraft 1 could have been directed to LA instead of KK and assigned to an available gate on the west side of Terminal 3 – an area far less congested. Additionally, advanced warning would allow Airline X the time to contact their neighbor, International Air Terminal, and possibly coordinate usage of their throats K or H. Both of these solutions require "look ahead" capabilities and, though current operations do take advantage of informal channels of communication in order to manage these types of operational constraints, SMS could improve the efficiency with which these operations are coordinated.

Additional Conflicts in this Scenario: Other issues that arise in this scenario involve Aircraft 4 - arriving on 13L shortly after Aircraft 1. Aircraft 4 is an international flight out of Madrid (MAD) assigned to park at Gate 15 on the west side of Terminal 3. The aircraft will be directed by the ATC Ground Controller to exit 13L at Y, proceed to X and on to A, where it will have to wait on the taxiway to enter LA as Aircraft 6 has recently pushed back from Gate 15 and is proceeding through LA. (See figure 4)

Aircraft 5, a 737, has arrived from Boston on 13L. This aircraft will be directed on the same surface route as Aircraft 1 - off the runway at ZA, cross at F to proceed down A in an attempt to reach its assigned Gate 28. However, this flight will encounter surface conflict when it reaches A because Aircraft 4 is already waiting in A for the departure of Aircraft 6 through LA. There is no alternative terminal for this aircraft as Terminal 2 is the only terminal appropriate for small aircraft and the only access to Terminal 2 is LA or MA. (See figure 4)

Aircraft 6 is departing to Los Angeles from Gate 15. Its assigned departure runway is 13R. This aircraft is late in departing and will therefore conflict with the arrival of Aircraft 4, which must wait for Aircraft 6 to proceed through LA. (See figure 4)

Aircraft 7, the final flight involved in the scenario, is pushing back from Gate 17 and is scheduled to depart from 13R bound for Albuquerque. Again, this flight will experience conflict at LA with Aircraft 4. Therefore, Aircraft 4 is further delayed on A.

Solution to these Additional Conflicts: These additional issues associated with Aircraft 4 – 7, also require advance identification of the surface conflicts. One suggestion to resolve this issue would be to modify the schedule of the flight. (This type of solution, however, is often resisted by airline marketing staff.) For example, if Aircraft 6 were scheduled to depart slightly earlier, then the arrival/departure conflict with Aircraft 4 would be avoided in LA if both aircraft were on schedule. Alternatively, a more adaptive solution could be considered – gate reassignment. If an appropriate gate could be identified where the conflict between the departing and arriving aircraft would be avoided, then Aircraft 4 could be reassigned. Another solution would be a modification of the surface routes of Aircraft 4 and 5. If Aircraft 5 were to arrive ahead of Aircraft 4 the conflict and delay caused by Aircraft 5’s attempt to enter Terminal 2 space via MA after Aircraft 4 enters LA would be avoided. By adjusting their routes (perhaps ATC Ground Control could direct Aircraft 4 to pause somewhere en-route prior to reaching the portion of A where conflict will occur) then the departure schedules of Aircraft 6 and 7 could be maintained causing just a slight delay in the schedule of Aircraft 4. Again, these specific conflicts are dealt with quite frequently and adequately using informal methods of coordination and communication. However, SMS could help streamline this process.

In Scenario 1, we illustrated a situation at JFK where SMS could be useful, but is not critical, because operators are currently able to use less formal methods to work around the problems highlighted in that example. There are, however, a number of other scenarios at JFK where SMS, with its ability to deliver real-time situation awareness and its ability to provide predictive data regarding operations, could significantly improve operations. As noted by the airline experts from JFK, for these other scenarios SMS could provide a "big operational advantage".

General Classes of Scenarios: There are a number of basic scenarios where real-time data or predictions from SMS could help the Airline X Airport Coordination Center (ACC) at JFK to improve performance. The opportunity for such performance improvements arise in part because staff in the ACC can’t see aircraft on all of the taxiways at JFK, in part because they don’t know the intentions of other airlines, in part because they don’t know what the actual off-times will be for aircraft in the queue to depart from a given runway, and in part because of the cognitive complexity of the task of tracking and predicting surface movement patterns. Below, a number of these basic scenarios are listed. Then a specific example is described in detail illustrating a situation where SMS would be very useful.

Note that, in some cases, several of these basic scenarios may co-occur (thus involving the interactions of several aircraft), requiring planning about how to deal with the different aircraft in different ways in order to resolve the conflicts. These conflicts can arise because one or more of the flights are either ahead of or behind schedule, or because the original plan was not sufficiently coordinated to avoid conflicts.

• Delayed arrival creating an opportunity for a departure to push-back earlier than planned

• Allow the departing aircraft to take advantage of the delayed arrival (such as an aircraft that is stuck in ground traffic on some taxi-way out of sight of the Airport Coordination Center), changing the plan for the departing aircraft in terms of its push-back and/or its taxi route – assuming that this is operationally viable (for example, that all passengers are on board). This scenario is most likely to occur in cases where the ACC is planning to deliberately delay a particular departure in order to accommodate the arrival, which has now been delayed.
• Departure interfering with a "more important" arrival because the departure occupies the assigned gate for the arrival

• Reassign the arrival to another gate (sometimes later ferrying it to the originally intended gate).
• Push-back the departure earlier – assuming that this is operationally viable (for example, that all passengers are on board).
• Departure blocking the movement of a "more important" arrival either in the terminal space, in the throat leading to the arrival’s assigned gate or on the taxiway

• Reroute the arrival via a different taxiway or throat.
• Reassign the arrival to another gate (sometimes later ferrying it to the originally intended gate).
• Reroute the departure via a different throat or taxiway.
• Hold the departure at its gate until the arrival has passed.
• Departure interfering with another "more important" departure in the terminal space (A departing flight pushing back from the gate delays the departure of another aircraft that needs to pass through the same terminal space)

• Hold the interfering departure at the gate longer.
• Push-back the interfering departure early – assuming that this is operationally viable (for example, that all passengers are on board).

• Departure interfering with a "more important" departure at a throat, taxiway or runway

• Reroute the interfering departure to another throat, parking area, taxiway or runway, or hold it at the gate.
• Reroute the "more important" departure via another throat, taxiway or to a different departure runway.
• Arrival interfering with a "more important" departure (An arriving flight’s position on a taxiway, throat or within the terminal space makes the departure of another aircraft impossible)

• Hold the arrival in an appropriate location (i.e., somewhere where it isn’t blocking the departure or other "more important" surface traffic).
• Reroute the arrival via another taxiway or available throat.
• Reassign the arrival to another gate (sometimes later ferrying it to the originally intended gate).
• Arrival interfering with a "more important" arrival (An arriving flight’s position on a taxiway, throat or within the terminal space makes the arrival of another aircraft impossible)

• Hold the interfering arrival in an appropriate location (i.e., somewhere where it isn’t blocking the departure or other "more important" surface traffic).
• Reroute one of the arrivals to another taxiway or available throat.
• Reassign one of the arrivals to another gate (sometimes later ferrying it to the originally intended gate).

Below, one sample scenario is described in detail to illustrate the potential value of SMS at JFK.

Several of the basic scenarios listed above focus on constraints associated with a common usage taxiway – specifically a taxiway (throat) that provides access to a common terminal. An example found at JFK would be the throats K and KK which are located southwest of Terminals 1 through 4. These throats are in high demand as they provide access to Gates 1 - 8 in Terminal 3 and Gates 27 - 35 in the International Air Terminal 4. Though K and KK are not, in a strict sense, common usage taxiways, as KK is "owned" by Airline X and K is "owned" by IAT (International Air Terminal – terminal management that provides facilities for multiple carriers at JFK), they are "common usage" in the practical sense – operations on one will effect operations on the other. Because of this, these two operators have developed an informal but critical dialogue that allows them to coordinate their operations for better planning and efficiency. Currently, this communication occurs in one of two ways: the Gate Coordinator must call IAT and request permission to use K (or vice versa) or, alternatively, the Gate Coordinator will direct the pilot to switch to IAT frequency and request ramp access permission directly. By providing a "same data source" for multiple carrier operations SMS would be "of immense value in coordinating the activities between two separate terminals, using two separate frequencies, in charge of two separate areas."

Another slightly different and even more rigid example of a common usage taxiway scenario is MA. In this scenario you have 1 taxiway, controlled by 1 operator, which provides access to two terminals – Gates 4, 6, 8, and 10 of Terminal 1 and Gates 26 – 29 of Terminal 2. This throat is used by multiple operators. However, it is controlled only by Airline X and therefore doesn’t require the coordinators to acquire permission as in the case of either K or KK. There are, however, several factors that contribute to the complexity of operations within this surface space. First, there is a lack of visual information, meaning that currently there is no means by which these operators can determine where on the airport surface an arriving flight is located as it moves down taxiways. SMS could be an advantage because "even when you do have a view, nobody’s ramp view is so comprehensive that they know where the arrival aircraft is on the whole airport. Airports are too big for that." Second, because of a lack of information regarding advanced operations data, Airline X must staff a fully qualified coordinator in Terminal 1 – at "an incredible expense" - in order to coordinate the blending of multiple push-backs with multiple arrivals between Terminals 1 and west 2. "SMS could give us enough information as to what’s about to happen, that we could probably eliminate that person in Terminal 1."

Unlike in operations involving access to Terminals 3 or 4 in which, with permission, access can be gained through 2 different throats, MA is the only access to east Terminal 1 and west Terminal 2, therefore, in the words of an Airline X coordinator, "the impact is much more real because Mike-Alpha is the only common taxiway…and it’s a fact that either they’re going or we’re going". By providing real-time situation awareness SMS would extend planning abilities and provide greater "on the fly " flexibility, meaning it could allow operators to take immediate advantage of push-back opportunities created when an arriving flight is delayed somewhere on the airport surface or when a push-back has been delayed by an aircraft being directed into a gate.

The following scenario illustrates the delayed departure of 2 flights and the delayed gate arrival of another flight within the constraints of a common usage taxiway.

Aircraft 1 – an aircraft departing to Boston - will be directed by the Gate Controller to MA. From there the aircraft will await instruction from the ATC Ground Controller. In this scenario the aircraft will have to wait for passing aircraft heading northwest on A and then will be directed by Ground Control to cross A to B, and head towards its departure runway 13L. At the time of this scenario "snapshot" Aircraft 1 is on B and has passed LA. (Multiple aircraft departing from Terminals 3 and 4 are in a departure queue heading northwest on A and are backed up to KK.

Aircraft 2 has arrived on 13L and is making its way to gate 26 in Terminal 2 via A. This aircraft will become stuck on A within the departure queue for 13R and is unable to transition to B due to the traffic (such as Aircraft 1) using B to taxi to 13L for departure.

Aircraft 3 is departing from gate 10 of Terminal 1 and will ultimately be directed out MA to A to runway 13R. However, in anticipation of the arrival of Aircraft 2 - an aircraft that will experience significant delays prior to reaching MA - Aircraft 3 will be held at its gate. Without awareness that Aircraft 2 is being delayed on A, the airline coordinator will miss the opportunity to push-back Aircraft 3 now, using MA to join the departure queue on A for departure on 13R (rather than waiting for Aircraft 2 to use MA).

Aircraft 4 is departing from gate 28 and will be delayed until Aircraft 3 has pushed back and cleared MA. Thus, the length of the delay for Aircraft 4 depends on when Aircraft 3 is pushed back. (see figure 5)

Solution: Surface position data displayed through SMS would allow the Gate Controller to identify Aircraft 2’s arrival delay on A. This information alone will allow the on-time departure of both Aircraft 3 and 4.

These scenarios dealing with surface movement at JFK are intended to illustrate problems that can arise at that airport, and possible solutions that could make use of SMS. To summarize, based on information received from subject-matter experts from JFK, the following are among the functions that could be aided by a suitably designed SMS:

Thus, from the perspective of airline Airport Coordination Centers, there is considerable potential value for SMS at airports like JFK. As one airline coordinator concluded:

Figure 2b: K and H

Figure 3: Spot located in throat KK

Figure 5: Aircraft 2 blocked by departure traffic on A