AAL CDM Message Sending Process. CDM A&D Meeting January 24-25, 2001 Presented by: Roger Beatty - Operations Coordinator American Airlines - System Operations Control. CDM Message Sending -Technical.
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CDM A&D Meeting
January 24-25, 2001
Presented by: Roger Beatty - Operations Coordinator
American Airlines - System Operations Control
AA CDM processing consists of the XPE/XPF Downloader, the CDM Data Collector (labeled above as CDM) and the Communications Program. All three execute once per minute.
The CDM Data Collector processing rules are:
A rolling download is performed. Whenever a flight reaches the number of hours prior to scheduled departure as set by a parameter, an initial FX or FM will be sent. Currently the parameter is set to 18.
Upon receipt of a cancellation from FOS, an FX will be sent.
Reinstatement of a cancelled flight:
When a cancellation is reinstated, an FC will be sent.
Diversion after takeoff:
An FM is sent for the diverting leg to change the destination station to the new station.
An FC is sent to create the continuation leg from the destination station to the original destination. This will have the same flight number as the diverting flight.
Undiverting a flight after takeoff:
An FX is sent to cancel the continuation leg. An FM is sent to change the destination station back to the original destination station.
An FX is sent to cancel the leg.
Two FCs are sent, the first to create the leg from the origination to the station into which the flight will divert. The second FC will create the leg from the station into which the flight diverts to the original destination.
Undiverting prior to take-off:
Cancel (FX) the two legs created by the diversion, and then send an FC to create the flight from the origin to the original destination.
Change of flight number (Stub):
If a flight is stubbed, an FM is sent to change the flight number. All FMs or FXs after this will be sent using the new flight number.
Reinstate the flight number to the original (unstub):
An FX is sent to cancel the flight with the stubbed number. Then an FC is sent to create the leg with the original flight number.
Air Interrupt (Diversion after take-off to the originating station):
AA cannot handle this properly as AA creates the continuation leg with the same scheduled departure time as the original leg. Thus when the FC is sent to create the continuation leg, Volpe rejects it saying that this flight has already occurred. To differentiate the legs within FOS it is necessary to enter the actual (latest) time as well as the scheduled departure time.
Prior to a flight taking-off, whenever any of the T1, T2, T3 or 4 times change from the prior time that was sent to Volpe by more than the number of minutes based on a parameter, an FM is sent to Volpe. Currently this parameter is set to one minute; thus any change in these times results in an FM.
Change of equipment:
An FM is sent if the equipment change results in the change of fleet as sent to Volpe. If the equipment is a tail number change within fleet, no FM is sent.
Prevention of time-outs:
This is governed by a "time-out minutes" which is currently set to 60. During each cycle, if a flight is:
Not yet OFF
Past the latest Off Time by the "time-out minutes" minus 15
The actual equipment is equipped with ACARS
Not already flagged to be sent to Volpe in this cycle
The flight becomes a time-out candidate and will have an FM sent to prevent time-out cancellation. If a time-out candidate is not yet OUT, the latest departure time for OUT will be set to time now and the other times adjusted accordingly. If a flight is OUT but not OFF, the estimated OFF is set to time now and the estimated ON and IN adjusted accordingly. At no time is the enroute time or taxi in minutes adjusted.