Before processing thousands of events, scenarios, etc. for feeding the Dashboard, I would like to show the a dimension that put in context almost every event. The time dimension. Delays are the “Oh, no, a delay again, what was the captain reason this time?” The late arrival of the plane, air regulation over the airport…I heard once that the guilty factor was the “shamefulness of being part of an airline because the ramp handling staff were late….some other details were given by the captain and it was a gesture of honesty”. We, the passengers only concern about only time milestone, the scheduled departure time of our flight, and pray for not have a big delay, but there are always 10, 15 minutes of courtesy. In this post, you will see dozens of time milestones, that impact over all the punctuality process of the flight operation and consequently will be marked in the Dashboard we are defining in this blog (this is the part V of this series).
The next graphic shows the general process of a flight turnaround from the arrival to the departure.
Aircraft Turnaround Process
In the next time lapse video, you can see the a Lufthansa turnaround process, including the arrival flight en-route track, ATC conversations, and the destination’s enroute track. Great video of the AirportFreak Blog.
So, after the general turnaround process with the main flight related activities shown in the graphic and video, it’s time to speak about times.There are three main groups of time’s milestones. The scheduled times, the estimated times and the actual times, almost the time’s metrics are around them. Prepare to view them:
| ACRONYM | DEFINITION | EXPLANATION |
| ACGT | Actual Commence of Ground Handling Time | The time when ground handling on an aircraft starts, can be equal to the Actual In-Block Time (AIBT) (to be determined locally) |
| ACZT | Actual Commencement of De-icing Time | The time when de-icing operations on an aircraft starts. |
| AEZT | Actual End of De-icing Time | The time when de-icing operations on an aircraft end. |
| AIBT | Actual In-Block Time | The actual date and time when the parking brakes have been engaged at the parking position. |
| ALDT | Actual LanDing Time | The actual date and time when the aircraft has landed (touch down) |
| AOBT | Actual Off-Block Time | The actual date and time the aircraft has vacated the parking position (pushed back or on its own power). |
| AOST | Actual On Stand Time | The time at which the aircarft stops at the stand |
| ARDT | Actual ReaDy Time | The time when the aircraft is ready for start up/push back or taxi immediately after clearance delivery, meeting the requirements set by the TOBT definition |
| AROT | Arrival runway occupancy time | The time interval between the aircraft crossing the threshold and its tail vacating the runway. |
| ARZT | Actual Ready for De-icing Time | The time when the aircraft is ready to be de-iced. |
| ASBT | Actual Start Boarding Time | The time when passengers are entering the bridge or bus to the aircraft |
ASRT | Actual Start Up Request Time | Time the pilot requests start up clearance |
| ATA | Actual Time of Arrival | The time at which a craft arrives at a specified point at a destination. |
| ATD | Actual Time of Departure | The time of leaving a specified point at a place. The actual time an aircraft becomes airborne. |
ATOT | Actual Take Off Time | The time that an aircraft takes off from the runway. (Equivalent to ATC ATD–Actual Time of Departure, ACARS = OFF) |
ATTT | Actual Turn-round Time | Metric AOBT – AIBT |
AXIT | Actual Taxi-In Time | Metric AIBT – ALDT |
AXOT | Actual Taxi-Out Time | Metric ATOT – AOBT |
| CET | Clearance Expiry Time | The expired time when an air traffic control authorisation by ATC for an aircraft to proceed under specified conditions within controlled airspaces |
| CLDT | Calculated LanDing Time | A flight’s frozen calculated landing time. |
| COBT | Calculated Off-Block Time | CTOT (Calculated Take-Off Time) minus taxi time. |
| CTA | Controlled Time of Arrival | An ATM imposed time constraint on a defined merging point associated to an arrival runway. |
| CTO | Controlled Time Over | An ATM imposed time constraint over a point. |
CTOT | Calculated Take Off Time | A time calculated and issued by the appro- priate Central Management unit, as a result of tactical slot allocation, at which a flight is expected to become airborne. (ICAO Doc 7030/4 – EUR, Table 7) |
| DROT | Departure runway occupancy time | The time interval between [the aircraft] crossing the stop bar at the holding point and the main gear lift-off from the runway. |
| EAT | Expected Approach Time | The time at which ATC expects that an arriving aircraft, following a delay, will leave the holding fix to complete its approach for a landing. |
ECZT | Estimated Commencement of De-icing Time | The estimated time when de-icing operations on an aircraft are expected to start |
| EDCT | Expect Departure Clearance Time | The time issued to a flight to indicate when it can expect to receive departure clearance. EDCTs are issued as part of Traffic Management Programs, such as a Ground Delay Program (GDP). |
EDIT | Estimated De-icing Time | Metric EEZT – ECZT |
| EDTO | Extended Diversion Time Operations | An EDTO is a flight by a turbine powered aeroplane where the time at the one engine inoperative cruise speed (in the ISA and still air) from a point on route to an adequate aerodrome is greater than the following; Twin engine aircraft certificated to carry more than 19 passengers or 3410 kilograms payload – 90 minutes Aircraft with more than 2 engines – 180 minutes Aircraft engaged in passenger carrying operations but not certificated to carry more than 19 passengers – 180 minutes. |
EET | Estimated Elapsed Time | The estimated time required to proceed from one significant point to another (ICAO) |
EEZT | Estimated End of De-icing Time | The estimated time when de-icing operations on an aircraft are expected to end |
EIBT | Estimated In-Block Time | The estimated time that an aircraft will arrive in-blocks. (Equivalent to Airline/Handler ETA – Estimated Time of Arrival) |
ELDT | Estimated Landing Time | The estimated time that an aircraft will touch- down on the runway. (Equivalent to ATC ETA –Estimated Time of Arrival = landing) |
EOBT | Estimated Off-Block Time | The estimated time at which the aircraft will start movement associated with departure (ICAO) |
| EOST | Estimated On Stand Time | The estimated time at which the aircarft will stop at the stand |
| ERDT | Estimated ReaDy Time | The estimated time when the aircraft is ready for start up/push back or taxi immediately after clearance delivery, meeting the requirements set by the TOBT definition |
ERZT | Estimated Ready for De-icing Time | The estimated time when the aircraft is expected to be ready for de-icing operations |
| ETA | Estimated Time of Arrival | (ICAO) For IFR flights, the time at which it is estimated that the aircraft will arrive over that designated point, defined by reference to navigation aids, from which it is intended that an instrument approach procedure will be commenced, or, if no navigation aid is associated with the aerodrome, the time at which the aircraft will arrive over the aerodrome. For VFR flights, the time at which it is estimated that the aircraft will arrive over the aerodrome. |
| ETD | Estimated Time of Departure | The estimated time at which an aircraft will become airborne. |
| ETO | Estimated Time Over significant point | Estimated entry time over an airspace for a non-regulated flight based on flight plan data and Environment Database (ENV) data. |
ETOT | Estimated Take Off Time | The estimated take off time taking into account the EOBT plus EXOT. |
| ETT | Estimated Time Interval | The earliest/latest ETA at a waypoint, provided the aircraft flies the 4D Trajectory at its max/min allowable speed, wind/temp error is also taken into account, in order to guarantee that any CTA defined within associated ETA min/max interval will be satisfied with high probability. |
| ETTA | Estimated Time Of Turn Around | The time estimated by the AO/GH (aircraft operator/ground handler) on the day of operation to turn-round a flight taking into account the operational constraints. |
ETTT | Estimated Turn-round Time | The time estimated by the AO/GH on the day of operation to turn-round a flight taking into ac- count the operational constraints |
| EXIT | Estimated Taxi-In Time | The estimated taxi time between landing and in-block. |
EXIT | Estimated Taxi-Out Time | The estimated taxi time between off-block and take off. This estimate includes any delay buffer time at the holding point or remote de-icing prior to take off |
| EXOT | Estimated Taxi-Out Time | The estimated time between off-block and take off. This estimate includes any delay buffer time at the holding point or remote de-icing prior to take off. |
| FRTT | Flight crew reaction time to ATC take-off clearance | The time interval between the ATC clearance for either line-up or take-off and commencement of taxiing to line-up. |
| IOBT | Initial Off-Block Time | The off-block time as given in the FPL and updated by flight plan associated messages (DLA, CHG, etc.). |
| LUPT | Line-up time | The time interval between crossing the stop bar and the moment the aircraft is fully lined up. |
MTTT | Minimum Turn-round Time | The minimum turn-round time agreed with an AO/GH for a specified flight or aircraft type |
| ROT | Runway occupancy time | The amount of time that each aircraft occupies the runway. |
| RTA | Required Time of Arrival | The aircraft function to follow a CTA |
SIBT | Scheduled In-Block Time | The time that an aircraft is scheduled to arrive at its first parking position |
| SLDT | Scheduled LanDing Time | The scehduled date and time when the aircraft has landed (touch down) |
SOBT | Scheduled Off-Block Time | The time that an aircraft is scheduled to depart from its parking position |
| SOST | Scheduled On Stand Time | The scheduled time at which the aircarf twill stop at the stand |
| STD | Scheduled Time of Departure | The scheduled time at which an aircraft will become airborne. |
| STOT | Scheduled Take-Off Time | Thescehduled take off time. |
STTT | Scheduled Turn-round Time | Metric SOBT – SIBT |
TLDT | Target Landing Time | Targeted Time from the Arrival management process at the threshold, taking runway se- quence and constraints into account. It is not a constraint but a progressively refined plan- ning time used to coordinate between arrival and departure management processes. Each TLDT on one runway is separated from other TLDT or TTOT to represent vortex and/ or SID separation between aircraft. |
TOBT | Target Off-Block Time | The time that an Aircraft Operator or Ground Handler estimates that an aircraft will be ready, all doors closed, boarding bridge removed, push back vehicle available and ready to start up / push back immediately upon reception of clearance from the TWR |
TSAT | Target Start Up Approval Time | The time provided by ATC taking into account TOBT, CTOT and/or the traffic situation that an aircraft can expect start up / push back approval |
| TTA | Target Time of Arrival | An ATM computed arrival time. It is not a constraint but a progressively refined planning time that is used to coordinate between arrival and departure management applications. |
TTOT | Target Take Off Time | The Target Take Off Time taking into account the TOBT/TSAT plus the EXOT. Each TTOT on one runway is separated from other TTOT or TLDT to represent vortex and/ or SID separation between aircraft. |
| VTT | Variable Taxi Time | The estimated time that an aircraft spends taxiing between its parking stand and the runway or vice versa. |
| WAIT | Wait time | The time interval measured between the completed line-up and the ATC clearance for take-off. |
I’m sure that there are more milestones, but I wanted to point out the relevance of the dozens of temporal milestones regarded to aircraft and airport operation, so measure them is basic for any airport dashboard. So we will count some of them in ours.
For more info:
Eurocontrol Lexicon. Eurocontrol website.
A-CDM Implementation Manual. Eurocontrol website.
Civil Aviation Safety Authority. Australian Government.