A publication of the National Air Traffic Controllers Association
Issue link: http://natca.uberflip.com/i/808779
s pring and s ummer as NASA refines their understanding of ATC and TMU operations at CLT. DATACOMM Chad Geyer (ZLA) is the Article 114 Representative for DataComm. Below is his update. Last week Controller Pilot Data Link Communica tion (CPDLC) sites sent almost 4000 clearances a day. About 33 of the 72 sites have upgraded to Version 12.3. Version 12.3 prepares sites for National Single Data Authority (NSDA) and fixes an issue with CPDLC failing when a certain chain of events occurs on the ground system. The DataComm ground system communicates with the avionics through the Future Air Navigation System (FANS). FANS was originally designed to send messages back and forth in the oceanic environment. The DataComm program decided to use a known avionic system that was already installed on some aircraft rather than trying to create a new system that would have to be installed. To date, more than 3 , 000 aircraft have FANS installed. FANS uses a predefined message set that is formatted in a w ay that the aircraft and ground system will know what type of messages are being sent. These are called Up Link Messages (UM) and Down Link Messages (DM). UM messages come from the ground system and DM messages come from the aircraft. The messages are furt her defined with a number; for example, UM19 is a Maintain Altitude up link. When the ground system up links a UM19 message it is preformatted to d isplay MAINTAIN {Altitude}. The ground system will format the message in such a way that the altitude value i s entered into the field. When the ground system up links the message , the aircraft's Multipurpose Control Display Unit (MCDU) will display the message in the appropriate format for the Flight Management Computer (FMC). When the message is displayed to pil ot, they are given Accept (DM0) and Reject ( DM1) responses as well as Stand by (DM2). Depending on the message type and aircraft avionics, there may be a load prompt for the pilot to enter the message value into the FMC. The load prompts are the time saver s for sending route information. The ground system will send up different varieties of messages depending on the part of the route that has changed. These messages are: UM74 PROCEED DIRECT TO [position] Instruction to proceed directly from the present posi tion to the specified position. UM79 CLEARED TO [position] VIA [route clearance] Instruction to proceed to the specified position via the specified route. UM80 CLEARED [route clearance] Instruction to proceed via the specified route. An example of a UM79 departure clearance : [U79] CLEARED TO FAREV VIA Rt(OTTTO@38d51.2 ' N078d12.3 ' W Q80 FAREV@37d12.4 ' N085d07.3 ' W) [U169] +LOAD NEW RTE TO FAREV+ AFTER FAREV CLEARED TO KDAL ARPT AS FILED [U169] REBLL3.OTTTO, CLIMB VIA SID [U169] EXPECT FL380 10 MIN AFT DP, DPFRQ 118.95, SQUAWK 2170 [U169] ----- KDCA REBLL3.OTTTO Q80 FAREV LAJUG J6 SOPIE J6 LIT DIRRK.HIBIL3 KDAL When a departure clearance is formatted , it also include s UM169 messages that are Free Text messages that are concatenated to the UM79 message. The UM79 message