I tried to comply with the GreenLandings® message, but was vectored by ATC?
Isn’t there too much confusion and variability in the terminal area to manage the arrival flow?
Won’t GreenLandings® interfere with Air Traffic Control or Traffic Management Advisory?
Won’t Air Traffic Control or Traffic Management Advisory interfere with GreenLandings®?
Our flights are already on time, how can GreenLandings® help?
How much of a change will GreenLandings® make to each aircraft?
This is a big problem. How can such small changes make a difference?
Avionics are tremendously expensive, what new gear do I need to put on my airframes?
I can see how this could work for my hubs, but what about non-hub airports?
I tried to comply with the GreenLandings® message, but was vectored by ATC?
First and foremost, GreenLandings® is a statistical benefit program. And although GreenLandings® can, and often does improve individual flights, the main goal of GreenLandings® is to improve the system solution.
As an example of a system benefit, when GreenLandings® is operational, the time from the arrival cornerpost to landing (Dwell Time) for all aircraft is reduced. This means that even if you are not able to make your individual RTA, your flight still benefits from the fact that other pilots were able to make their RTA.
Of course, the more often you can make the RTA, the better the system will work. As one pilot stated, “When I receive the GreenLandings® message, I am able to comply 70% to 80% of the time, and the more messages I receive, the better I get at meeting the GreenLandings® RTA goal”. In the current implementation, successfully meeting the GreenLandings® RTA 70% of the time is considered successful.
The GreenLandings® time change request is too large?
While the GreenLandings® and FMS cornerpost time predictions are usually very accurate, there are times that the FMS cornerpost time is different than GreenLandings® cornerpost time.
In the millions of GreenLandings® messages sent since GreenLandings® went operational, ATH has received only a very small number of error messages from pilots. ATH personnel have analyzed each report in depth. The largest portion of the problems found thus far stem from the FMS.
Therefore, if the speed change required by the GreenLandings® message seems excessive, the first step should be to crosscheck the FMS calculation. After assuring the latest winds are entered correctly, which is important, simply go to the PROG page and replace the Destination with the target cornerpost fix. The FMS will then show distance (on the FMS routing) and time to the target cornerpost. Then divide the distance to the cornerpost by the groundspeed in nautical miles per minute. For example, if the FMS shows 624 NM to the target cornerpost, and the aircraft is traveling 8 NM/minute, it will take 78 minutes to reach the cornerpost. Absence any large wind changes (usually visible on the Flight Plan), the aircraft will reach the cornerpost 78 minutes later.
Isn’t sequencing FAA’s job?
While FAA is indeed part of the solution, it is incumbent upon the pilots to manage their aircraft. From a business perspective, too often aircraft arrive early and wait for a gate, or an aircraft lands early only to delay another late aircraft.
And while FAA is responsible for the safe separation of aircraft, FAA should never be concerned with the business decisions by each pilot, operator or airline. GreenLandings® is an operationally proven, tactical aircraft landing management tool, and can only be done efficiently by the person that owns the aircraft. Only the aircraft operator or airline knows the economic priorities for each of their assets/aircraft at any given moment.
Isn’t there too much confusion and variability in the terminal area to manage the arrival flow?
While we agree that there is a lot of confusion and variability within the terminal area, this is an outcome and symptom of the unmanaged, highly variable landings times and not a constraint to managing the aircraft landing times.
In other words, real time landing time management will prevent much of the confusion and variability within the terminal area around the airport.
Won’t GreenLandings® interfere with Air Traffic Control or Traffic Management Advisory?
No.
Think of the ATC arrival problem like a deck of cards. Currently ATC takes the aircraft as they arrive, and then sorts them out based on the first come, first served principle. While the first come, first served process meets the safety goal, most times this sequence is very costly to the operator, pilot or airline, especially at the busier airports.
Conversely, GreenLandings® takes the random deck of cards and presorts it hours prior to landing based on the user’s business needs. Not only is this “ordered deck” of cards more profitable for the operator, managing a presorted deck makes the ATC task more stable and predictable.
In the end, whether the arrival flow is presorted (GreenLandings®) or left to random chance (today’s operation), the ATC system will do what it does today – make the necessary tactical changes to insure a safe operation.
Won’t Air Traffic Control or Traffic Management Advisory interfere with GreenLandings®?
No.
First, GreenLandings® improves the landing time flow to the aircraft, making ATC’s task easier. Further, GreenLandings® expects that a certain percentage of flights will be vectored or otherwise modified by air traffic control. GreenLandings® will simply mark this particular flight as “untouchable” and move on.
Keep in mind that with the passage of time more and more flights are coming into the picture. GreenLandings® will work these flights around the “untouchable” flights to get the most out of the airspace.
What does GreenLandings® do during irregular operations?
Using GreenLandings®, an aircraft operator can expect a later entry into, and less severe “irregular operations”. But once in an irregular operation, GreenLandings® does the same thing it does during regular operations.
GreenLandings® calculates an optimum time for each aircraft to arrive at the runway. Obviously, during irregular operations, it may not be possible to generate a solution for all airborne aircraft due to the speed limitations imposed by the operator, but the information provided by GreenLandings® is still very useful.
For example, GreenLandings® web site will provide the operator the predicted queue and the position of each aircraft in the queue. If the aircraft is expected to hold for 30 minutes, and the aircraft has only 20 minutes of fuel, it makes little sense to wait for 20 minutes and then divert. Having this information well ahead of time lets the pilot/dispatcher make aircraft by aircraft decisions about holding versus proceeding to an alternate airport.
Our flight is already on time, how can GreenLandings® help?
If your aircraft is on time, GreenLandings® will save fuel and prevent CO2. Not only can GreenLandings® save fuel, but it can also help shave off flight time, while improving on time performance.
How much of a change will GreenLandings® make to each aircraft?
The maximum change that GreenLandings® will make to an individual aircraft will typically be below the range of 5% of current cruise speed or 10 knots as specified in the Aeronautical Information Manual. Additionally, the amount of change requested by each aircraft is an operator policy decision that is easily configurable with in the GreenLandings® software.
This is a big problem. How can such small changes make a difference?
GreenLandings® is a 24/7-365 operation. It looks at every flight and makes a small adjustment to each flight. By making hundreds of small adjustments day in and day out, GreenLandings® provides significant benefit. For example, when an airport is at or above capacity, given the random flow of aircraft queuing theory, ATH Group’s analysis shows that the arrival queue increases exponentially. This is because once capacity is reached, ATC has only one option – de-peak the landing time flow backward in time by adding more and more delay to each successive aircraft.
Conversely, by acting hours prior to landing, GreenLandings® identifies the aircraft at the head of the queue and moves those aircraft forward in time, even if those aircraft are ahead of schedule. Speeding up even a few aircraft at the head of the queue into what would have been wasted landing slots pulls the entire queue forward.
In other words, moving 2 aircraft off the front end of the queue of 30 aircraft doesn’t save 2 minutes; it saves 2 minutes times every aircraft in the queue behind those 2 flights. In this case dropping 60 minutes from the actual arrival flow.
This recapturing of unused slots forward in time is a very powerful near-term benefit, which begins the very first day GreenLandings® is operational.
Secondly, better organization of the landing queue behind the first few aircraft reduces the variance of the arrival flow and provides ATC a more predictable and solvable problem. This requires less vectoring, and therefore less flight time. Again, a day 1 benefit.
Without the GreenLandings® feedback control mechanism an unused landing slot is gone forever. Dr. John-Paul Clark (Georgia Tech) called it the “draft” effect because each of these lost opportunities affects all aircraft behind it, sometimes for the rest of the day.
How many messages will GreenLandings® send each aircraft?
Usually just one, but this is a matter of operator policy.
There are times when a second message could improve the solution. In those cases, GreenLandings® may send two messages during a flight if the operator allows. ATH is very aware of not overloading the pilot with marginal information.
How will our pilots calculate the new arrival time (i.e., RTA)?
Pilots have been trained since the beginning of flight to do distance, speed versus time calculations. Obviously, having a Flight Management Computer (FMC) in the aircraft makes meeting the GreenLandings® time easier.
Many aircraft FMC’s allow entry of a specified time at the arrival fix (RTA). With this RTA function, all the pilot need do is enter the fix time sent by GreenLandings®. Even with a non-FMS aircraft, given the accuracy of the flight plans, meeting the GreenLandings® time within +/- 30 seconds is reasonable.
Military pilots routinely practice “time on target” operations within seconds. This is not a new task for pilots.
Avionics are tremendously expensive, what new gear do I need to put in my aircraft?
No new gear is required on any aircraft.
How difficult is the system to operate the GreenLandings® solution?
Once set up, GreenLandings® is almost fully automated. The system will calculate solutions, update the passive web landing time display and/or send messages to each aircraft on its own.
It is only necessary to monitor the process and adjust input parameters such as airport arrival rate or goal scenario. On some days you may wish to optimize fuel more strongly, or other days schedule or gate availability might be more important.
I can see how this could work for airline hubs, but what about business jets at non-hub airports like Teterboro (TEB)?
At the smaller and Business jet airports, it is still very valuable to know where you fit within the landing queue. If a small change can put even a single aircraft forward of the landing queue, versus the middle of a landing queue, it will save you and those behind you flight time. These minutes may very well make the difference in aircraft being on time or late.