Just For Pilots


GreenLandings® works by predicting the cornerpost, runway and gate times for all arrival aircraft, starting hours prior to landing. Then GreenLandings® values this outcome and uses a proprietary real time optimization software engine to search for a better system outcome for each the aircraft. 


Once GreenLandings® finds a better landing time, this will initially be converted to a web viewable congestion graph for pilots to evaluate and alter their landing time as needed.


Within months, GreenLandings® will convert the better landing time to a cornerpost time and send a RTA cornerpost message directly to the pilot. The reason GreenLandings® uses the cornerpost as the action point is so that pilots can confidently time navigate to the cornerpost, but not the runway or gate.


Rules of the Road


Although GreenLandings® works independently of the Air Traffic Control system, it is designed to be completely compatible with it. To ensure this compatibility, there are certain “rules of the road” that are very simple and very important to the success of the program:


  1. Always disregard GreenLandings® for any ATC instructions. Once an ATC instruction has been received (a vector or a speed change, or any other changes) simply disregard GreenLandings® and follow ATC instructions. There is no need to report this. GreenLandings® is continuously monitoring the flight and will know immediately if you are unable to comply for any reason.
  2. Do not use the ATC frequency to talk about GreenLandings® landing times or priorities. This will not only unnecessarily increase the chatter on the ATC frequency, ATC controllers will not be able to answer questions about the GreenLandings® program. Instead, please direct all questions or problems to company dispatch.
  3. GreenLandings® messages will request a speed change of up to 2 minutes or 16 kts (about .03 mach), whichever is less, as set by each operator or airline. The Aeronautical Information Manual states: “notify ATC for a “Change in the average true airspeed (at cruising altitude) when it varies by 5 percent or 10 knots (whichever is greater) from that filed in the flight plan”. All GreenLandings® changes should be within this guideline.
  4. If the pilot receives a direct routing from ATC after receiving a GreenLandings® message, maintain the last computed speed, i.e., do not slow down to make the GreenLandings® RTA. This will usually indicate that the controller has identified a potential benefit in direct routing and allow the GreenLandings® queue to collapse forward in time. GreenLandings® will note it and plan around it.
  5. As the pilot approaches the airport (within 200 to 300 NM), the ATC controller may begin to provide speed restrictions or in-trail vectors (i.e., arrival metering or in trail with another aircraft). The fact is that, with GreenLandings®, the speed changes and vectoring will be less. Once this happens, please disregard the GreenLandings® corner post time.
  6. Report problems to dispatch. Like all sophisticated computer systems, there is the possibility of GreenLandings® generating a time that falls outside the guideline. This could be due to bad input data, a software logic error, or even an avionics error. If this happens, please disregard the GreenLandings® message and report the error. As much information as is easily available would be helpful (like time received, what the error was, current estimate etc.), however, it is important to know there was a problem even if you don’t have the related data. This allows us to find the problem and correct.
  7. Although it is important from a profitability viewpoint to try to make the GreenLandings® landing time, if for any reason you are uncomfortable with the GreenLandings® corner post time, simply disregard. As is always the case, before altering speed based on an GreenLandings® message, the pilot should evaluate fuel, time distance, weather, etc., to assure a safe operation. Again, there is no need to report this.
 

Time Based Navigation Techniques


An FMS aircraft will obviously have an easier time meeting the GreenLandings® RTA. But even with a non-FMS aircraft, the company’s flight plans are accurate and can be used to calculate the ground speed change necessary to meet the GreenLandings® time. Suggested techniques to meet the GreenLandings® time include:


  1. FMS Crosscheck – While the FMS is usually very accurate, there are times when the FMS cornerpost time is different than the GreenLandings® cornerpost time. 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 winds are entered correctly, an important step, 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 mile per minute. For example, if the FMS shows 624 NM to the target cornerpost, and the groundspeed is 480 kts (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.
  2. Directs – If the pilot receives a direct prior to receiving the GreenLandings® RTA, the FMS may, or may not, compute abeam points. If the FMS does not calculate abeam points (with the entered winds), the FMS cornerpost prediction could be inaccurate. Please assure that there is adequate abeam points and up to date wind data on your route to increase the accuracy of the FMS cornerpost time calculation.
  3. FMS RTA – When using the RTA function in some FMS, it only alters the aircraft speed during the cruise phase of flight, and not in the descent phase of flight. If this is the case, given that the cornerpost is usually into the descent, it limits the time the FMS has to meet the RTA and the FMS may calculate a higher than anticipated speed change. To minimize this effect, once the pilot receives the GreenLandings® RTA, adjust the Cost index (which effects cruise and descent speeds) so that the calculated cornerpost time in the FMS is close to the GreenLandings® RTA. Once this is done, the pilot can then input the RTA in the FMS to refine the enroute speed change to more accurately meet the GreenLandings® RTA.
  4. Speed Adjustments – a .01 change in mach equals 5 to 6 knots of TAS. To gain 1 minute over 1 hour, will require an increase from .76 mach to .775 mach. To gain 2 minutes – will require an increase from .76 mach to approximately .79 mach. For a given mach number above the IAS to mach climb cross over point (narrow body FL 250, wide body FL 270), climbing decreases TAS, while descending increases TAS.
  5. Climb/Descent – For a fixed mach, a 2,000 foot change in altitude changes the TAS by approximately 5 kts. For example, if you hold .75 mach, climbing from FL330 to FL370 will decrease TAS by 10 knots. Make sure to check winds at both altitudes.
  6. FMS Aircraft – Enter winds, crossing restrictions and descent speeds. Enter corner post and GreenLandings® time on the RTA page. For non-RTA aircraft, adjust speed such that the FMS fix time equals the GreenLandings®  time. Fine tune as necessary.
  7. Non-FMS Aircraft – Make initial speed adjustment using the flight plan. For example, after takeoff, the pilot does the time computation on the flight plan and sees that they would arrive at the corner post at 1737Z. Approximately 2 to 3 hours from the corner post, they receive an GreenLandings® suggested corner post time of 1735Z. Assuming that there is 1 fix halfway between the aircraft and the corner post, the pilot would need to increase speed so as to arrive at the first fix 1 minute ahead of flight plan. This speed would then put the aircraft 2 minutes ahead of flight plan at the corner post.
  8. Another non-FMS 4D tool is groundspeed management. Using the FMS or flight plan groundspeed of 480 kts (8 NM per minute), to make up 2 minutes 1 hour prior to the corner post, the pilot must increase speed by 16 kts TAS (8NM/min x 2 minutes/1 hour). If the pilot had to lose 3 minutes 2 hours from the corner post, they would have to slow by 16 kts TAS (8NM/min x -4 minutes/2 hours).
  9. Time/Distance – Once within DME range of an arrival VOR, calculate the distance to the corner post and divide by the groundspeed (NM/min) to find minutes remaining to the corner post. Fine tune speed as necessary.
 

Conclusion

 

GreenLandings® is a proven and innovative way for pilots, airports and airlines to manage their aircraft. GreenLandings® offers pilots, airports, airlines and employees an opportunity to move ahead of the competition. We appreciate all of your help in making this program successful.