Movement Messages
Stations report each flight’s movements to Ops Control by teletype, in the format of IATA’s Airport Handling Manual. The departure and arrival entries on the Alerts are raised from these, and the Schedule and a flight’s panel show what they’ve said, so a flight stays due off until its departure message is in. The Messages tab (Alt+G) has the last two days’, text as sent, newest first; press F to find a flight, station, registration or message type. Aircraft send messages of their own too (see From the aircraft, below). Their routine position reports are left out of the list until you press P to show them.
Departure
Sent at pushback, with the off-block time alone (AD1245), and again once the aircraft is airborne, with both times.
MVT UE101/05.GUEAA.LHR AD1245/1253 EA1559 JFK DL93/15/0020/0005 DLA93Z PX112
UE101/05.GUEAA.LHR- Flight, day of the month of its scheduled departure, registration, and the airport of movement. Airports without an IATA code go by their ICAO code.
AD- Actual departure: off-block, then airborne.
EA- Estimated touchdown, and the destination.
DL- Delay codes and how long each held the flight, as hours and minutes. Up to two;
EDLcarries two more. If there were more than four causes, the rest are put down to the largest. DLA- Delay sub-codes.
PX- Passengers on board.
All times are UTC. The codes are in the Glossary.
Revised estimate
When the crew’s in-range call puts landing 5 minutes or more from the estimate the station last had, from the departure message or from the aircraft itself, the station they’re coming to sends a new one. The airport on the second line is that station.
MVT UE101/05.GUEAA.JFK EA1612
At the stand
At every airport, the station’s departure control system says when boarding starts, and when the flight is closed, doors shut and ready to go. A positioning flight, with no one to board, is only closed. Neither raises an Alert: the flight’s panel and the Schedule show them.
DCS UE101/05.GUEAA.LHR BOARDING1225
DCS UE101/05.GUEAA.LHR CLOSED1245
Target times
At an airport running A-CDM, the station gives the tower
the flight’s TOBT from 40 minutes before it’s due, and again when it changes. The tower replies with
its place in the departure sequence, and the aircraft pushes back no earlier than its TSAT: ready
early, it waits at the stand with its doors closed. When a flight pushes back, the tower fits the
ones still waiting round it again, and gives any whose TSAT moves a new one. The times
are on the flight’s panel. With no time to give (no crew, hangar work overrunning, or next information instead of an estimate) the TOBT is withdrawn
(TOBT NIL), and after a tail swap the times are given again for the new aircraft. Airports
without A-CDM give no target times: aircraft push back when ready and queue for the runway.
CDM UE101/05.GUEAA.LHR TOBT1245
CDM UE101/05.GUEAA.LHR TOBT1245 TSAT1247 TTOT1304
TOBT- Target off-block time: when the aircraft is expected to be ready.
TSAT- Target start-up approval time, from the departure sequence.
TTOT- Target take-off time: the TSAT and the taxi out.
Delay
Sent when a flight will leave late, and again when that changes. A station knows of a late aircraft when it hears the aircraft has left for it, of a problem on the ground shortly before departure, and of hangar work running on when it does.
MVT UE101/05.GUEAA.LHR ED051315 DL93/0025
ED- Estimated departure: day of the month and time.
NI- Next information: when there’ll be more word, given in place of
EDwhen there’s no estimate. SI- Supplementary information, in words.
Arrival
Sent as the aircraft touches down, with the touchdown time alone (AA1555), and again once it’s on blocks, with both times. Only the second raises an Alert.
MVT UE101/05.GUEAA.JFK AA1555/1603
AA- Actual arrival: touchdown, then on-block.
From the aircraft
Each aircraft reports its own movements over its datalink, as MVA: the same message,
sent by the aircraft. There are four, known as OOOI: Out of the gate, Off the ground, On the ground
and In at the gate. They update the Schedule and the flight’s panel, which says the flight has
landed and is taxiing in from On, and raise no Alert. Where a station’s message and the aircraft’s
differ, Ops Control goes by whichever was sent later, however long it took to arrive.
MVA UE101/05.GUEAA.LHR AD1245/1253 EA1602 JFK
MVA UE101/05.GUEAA.JFK AA1555
In the air it sends a position report at a set interval, and one whenever it’s asked
(POSREQ, or Request Report on the map):
POS UE101/05.GUEAA 5132N00027W 0712 F350 EA1602 JFK FOB12400
RQP UE101/05.GUEAA
POS- Position report: the position in degrees and minutes, the time it was sent, the flight level; then the aircraft’s estimate of touchdown, the destination and the fuel on board in kilograms.
RQP- Ops Control’s request for a position report.
Over HF datalink a message arrives some minutes after it was sent, and may not arrive at all. The time above each message in the list is when Ops Control had it.
Schedule changes
Ops Control sends an ad hoc schedule message (ASM), in the format of IATA’s Standard Schedules Information Manual, when a flight is retimed or cancelled. Estimates already given for that flight no longer stand once it’s received.
ASM UTC TIM UE101/05JAN LHR0730 JFK1030
TIM- A change of time: the flight, its date, then the leg with its new times. A time on another day has its day in front.
CNL- A cancellation: the flight and its date.