This operation allows the operator to correct the erroneous fields upon the reception of a CHG or ICHG message.
Whenever a change is made to the data contained in a Flight Plan message already sent to the ATSUs concerned with the flight, they must all be notified. It is particularly important to notify changes of Flight Level or Flight Rules, whether the change is made before departure or en-route. Such notification may be done by phone or ATS/DS when possible; otherwise it must be done by means of a modification message sent to AFTN.
The following CHG fields can be corrected through this operation:
CHG content: callsign aircraftIdentification (F7a), assignedSSRCode /Mode (F7b/c), departureAerodromeDesignator (F13a), estimatedOffBlockTime (F13b), destinationAerodromeDesignator (F16a), totalEstimatedElapsedTime (F16b), otherInformation (F18), amendments of other ICAO fields (F22), alternativeDestinationAerodromeDesignator (F16c).
In CHG, F22 should only amend F7b/c, F8, F9, F10, F13b, F14, F15, F16, F18, F19.
The following ICHG fields can be corrected through this operation via decoded data:
departureAerodromeDesignator (ADEP), destinationAerodromeDesignator (ADES), aircraftIdentification (ARCID), aircraftTypeICAOIdentifier (ARCTYP), NCAEquipment (CEQPT), estimatedOffBlockDate (EOBD),
estimatedOffBlockTime (EOBT), fillingTime (FILTIM), ifplid (IFPLDID), numberOfAircraft (NBARC), surveillance equipment (SEQPT), dataSourceId (SRC), assignedSSRCode/Mode (SSRCODE), wakeTurbulenceCategory (WKTRC), totalEstimatedElapsedTime (TTLEET), flightRules (FLTRUL), flightType (FLTTYP), alternativeDestinationAerodromeDesignator (ALTRN1/2), icaoRoute (ROUTE), requestedFlightLevel (RFL), enRouteCruiseSpeed (SPEED / MACH), rtepts (RTEPTS), sidDesignator (SID), starDesignator (STAR).
Other fields managed by this operation are included in specificADEXPField, otherInformation and supplementaryInformation, and listed in previous section "Operations"..