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Online Coordination

Slot Performance Monitoring







1.     Purpose of slot monitoring


Pursuant to EU Reg 95/93, Art 4, par 6, the schedule facilitator shall monitor the conformity of the air carriers' operations with the schedules recommended to them and the coordinator shall monitor the conformity of air carriers' operations with the slots allocated to them. According to WSG 8.9.2, the coordinator’s monitoring function is established in order to ensure adherence to allocated slot times within normal operating tolerances. Airlines must not intentionally operate services at a significantly different time or intentionally use slots in a significantly different way than allocated by the coordinator. In case of non-compliance, the coordinator will impose sanctions as described in this document.


2. Principles of slot monitoring by the coordinator


  1. Establish objective, transparent and non-discriminatory criteria
  2. Identify the intentional misuses of slots
  3. Give to the operators the opportunity to proceed to corrective actions
  4. Ensure that monitoring of slots will improve the airport operations


3.  Definitions (in alphabetical order)


Air Carrier: An air transport undertaking entity, holding a valid operating license or equivalent at the latest on 31 January for the following summer season or on 31 August for the following winter season. The definition of Air Carrier shall also include business aviation operators, when they operate according to a schedule; the definition shall also include all civil aircraft operators.


Beyond its reasonable control, this could include:


  1. Weather conditions
  2. Industrial actions
  3. Air traffic control regulations
  4. Technical issues


The responsibility of justification is on the carrier to demonstrate that the noncompliance with the cleared times was beyond reasonable control.


Facilitator: The organization or individual responsible for collecting data on planned operations at a Level 2 airport and recommending voluntary schedule adjustments as necessary.


Coordinator: The organization or individual responsible for slot allocation at a Level 3 airport.


Coordination Parameters: The limits of all technical, operational and environmental factors of the airport.


Intentionally: A landing or take-off with intentionally different characteristics than the allocated slot. A typical example of misuse is when published schedule times are the same with actual block times and differ from allocated slot times.


Landing and take-off: Landing and take-off shall mean the times at which the aircraft stops or starts moving under its own or external power.


Repeatedly: Recurring discrepancies during the current IATA scheduling season on a particular scheduled or non-scheduled service operated by an air carrier to or from the airport in question.


Significantly different time: Any difference between the intended (planned) landing or take-off time and the allocated slot time which breaches the coordination parameters for the airport, will be regarded as a ‘’significantly different time’’ as it is likely to affect other air carriers.


Significantly different way: Carriers will be considered as operating in significantly different way when


  1. Operating a different size category aircraft than the aircraft of the allocated slot
  2. Operating with an aircraft with more/less seats than those indicated in the allocated slot
  3. Operating with false indication of Service Type in the allocated slots that affects airport parameters
  4. Operating with intentionally false indication of route (e.g. SCHENGEN -NON-SCHENGEN) that affects airport parameters


Slot: Means the permission given by a coordinator to use the full range of airport infrastructure necessary to operate an air service at a coordinated airport on a specific date and time for the purpose of landing and take-off as allocated by the coordinator (EEC 95/93 as amended).


Slot Tolerance: Slot Tolerance Time at all Greek Coordinated Airports is +/- 20 minutes both for arrival and departure times (HCAA Airport Regulation No 4). Slot Tolerance Time (+/- 20 minutes) should not be correlated with the difference between published schedule time and allocated slot time. Tolerance time is subjected to operational reasons.


4. Types of slot misuse


The most common types of misuse are when the air carrier


  1. Operates according to published schedule time which is different from the allocated slot time (OFFSLOT)
  2. Uses a slot in a significantly different way (DIF) than the allocated slot, where, such use, causes prejudice to airport or air traffic operations (as described in the Definitions of this document)
  3. Operates a flight without an allocated slot (GOSHOWS) with the exception of flights as described in AIP Greece GEN 1.2 article

i)                 All VFR flights

ii)                Flights which are diverted to an alternative aerodrome for technical or meteorological reasons

iii)              Flights undertaken for humanitarian reasons

iv)              Flights on search and rescue missions

v)               Sanitary flights

vi)              State flights

vii)             Military flights


  1. Fails to operate a slot allocated by the coordinator without cancelling it in advance, and thereby causing prejudice to airport (NOSHOWS) apart from flights that fall into the scope of EC 95/93, Article 10, par 4, as follows:


i. unforeseeable and unavoidable circumstances outside the air carrier's control leading to

• grounding of the aircraft type generally used for the air service in question;

• closure of an airport or airspace;

 • serious disturbance of operations at the airports concerned, including those

  series of slots at other Community airports related to routes which have been

  affected by such disturbance, during a substantial part of the relevant

  scheduling period;

ii. interruption of air services due to action intended to affect these services which makes it practically and/or technically impossible for the air carrier to carry out operations as planned;

iii. serious financial damage for the Community of the air carrier concerned, with, as a result, the granting of a temporary license by the licensing authorities pending financial reorganization of the air carrier in accordance with Article 5(5) of Regulation (EEC) No 2407/92;

iv. judicial proceedings concerning the application of Article 9 for routes where public service obligations have been imposed according to Article 4 of Regulation (EEC) No 2408/92 resulting in the temporary suspension of the operation of such routes.





  •  Each of the above types of misuse must be deemed intentional before the carrier will be liable for possible sanctions. The carrier should be ready to provide records to the coordinator if the slots fall into the exceptions of the above types of misuses
  • In any case, proven misuse will be counted against the 80-20 rule as regards historic eligibility
  • There may be other forms of slot misuse which become identified over time, and which may also need to be addressed in the future
  • Sensibility is shown to flights that operate to recover service (e.g. AOG) and relieve passenger inconvenience. These flights are still obliged to request a slot.


5. Cases of OFFSLOT operation exceeding the Slot Tolerance Times


Based on EU reg 95/93, Art 14, par 4, the Coordinator shall monitor the


  1. Operation of a series of flights at times significantly different from the allocated slots (OFFSLOT)
  2. Operation of an ad hoc flight at times significantly different from the allocated slots (OFFSLOT)


In both cases, the Slot Tolerance times are +/-20 minutes for arriving and departing times (HCAA Airport Regulation 4) for performance monitoring purposes.


6.    Monitoring Procedures and Methods


Before the Date of Operation


Coordinators shall seek to prevent slot misuse by undertaking conformity checks before the date of operation, where possible. The following data sources (indicatively but not exhaustively) may be used to detect inconsistencies:

  1. Published schedule data (websites, CRS, timetables, brochures, tickets, etc.)
  2. Data of the airport concerned or from another airport that is part of the particular service (e.g. cooperation with other coordinators)
  3. ATC flight plans
  4. Any other relevant source


Coordinators shall check for following types of inconsistencies:


  1. Intention to operate with no slot
  2. Slot held with no intention to operate
  3. Intention to operate at a time different than the allocated slot
  4. Intention to use a slot in a significantly different way than allocated


If any of the above is detected, the coordinator shall cooperate with the carrier concerned for corrective actions.




After the Date of Operation


After the date of operation, Coordinators shall compile a database of actual

operations compared to allocated slots, updated on a weekly basis. This data will be analyzed to detect inconsistencies and identify slot misuse. For this comparison, the coordinator will use data provided by the airport operator and / or any other data sources (e.g. ATC).


Coordinators shall check for inconsistencies in the use of slots, such as:


  1. Operations with no corresponding slot
  2. Slot held but not operated
  3. Operations at a time different than the allocated slot
  4. Use of a slot in a significantly different way than allocated (e.g. use of a different aircraft)
  5. Distinguish repeated (possibly intentional) OFFSLOT operations from random operational variations (Change of A/C due AOG, heavy rotational delays etc.)
  6. Check whether the deviation is a result of an obvious operational disruption (e.g. known events of extreme weather, strikes, etc.)
  7. Check for evidence of intentional slot misuse such as published schedule time different than the allocated slot time, or operations closer to the requested time than the allocated slot time
  8. Check whether the requested time or turnaround time is appropriate for the route and aircraft type for standard turnaround operations


Follow up actions and cooperation with carriers


  1. Where there is evidence of a significant discrepancy in the use of slots         and/or apparent evidence of intentional slot misuse, the coordinator shall contact in writing the carrier concerned. A reply with explanatory notes and corrective actions should be sent within five (5) business days.
  2. Coordinators will try to identify slot performance issues as soon as possible and contact, in writing, the aircraft operator concerned in a timely manner, giving the carrier the opportunity to take corrective action in a time period agreed with the coordinator.
  3. For operations without a slot, coordinators should check whether the          reasons invoked by the carriers to be exempted from slot allocation fall into the exemption reasons indicated in Article 4, par c, of this document
  4. If an adequate explanation is provided and/or appropriate corrective action is taken, the coordinator shall continue to monitor the situation.
  5. If no adequate explanation is provided, the coordinator may take further      appropriate actions


General Actions and Sanctions


  1. Issue a warning
  2. Request for corrective actions
  3. Summoning before the Coordination or Slot Performance Committee
  4. Lower priority in the allocation of slots
  5. Loss of historic precedence
  6. According to the Regulation (EC) No 95/93 and its amendments, in case of air carriers that intentionally operate air services at a time significantly different from the allocated slot as part of a series or use slots in a significantly different way from the allocated and thereby cause prejudice to airport or air traffic operations, or without prejudice to Article 10(4) of EEC 95/93, if the 80% usage rate, as defined in Article 8(2), cannot be achieved, after an allotted time corresponding to 20% of the period of the series, no slots of that series have been used, the coordinator may enforce articles 14.4 / 14.6.(a) / 14.6.(b) of the Regulation (EC) No 95/93 as amended.
  7. Report the case to the Civil Aviation Authority to undertake appropriate legal measures (fine imposition)


7. Monitoring Procedures regarding each type of slot misuse


a. Operation of flights without an allocated slot (GOSHOWS): 

In the absence of any explanatory remark in the actual flight data, as received from the airport operator, a first warning will be issued immediately after data processing. In case a response is not issued, a second warning will be sent after the five (5) business days. Five (5) business days after the second warning, the unjustified cases will be forwarded to the Civil Aviation Authority for further appropriate actions.


b. Failure to operate a slot without cancelling it in advance (NOSHOWS): 

A first warning will be issued at the first misuse immediately after data processing. In case of repeated violations, after failure to demonstrate 80% usage, the series for the remaining period will be withdrawn and returned to the slot pool. Additionally, the historical precedence for the next equivalent period will be lost.


c. Different service type:

Correlation with the data for the remaining series and sending a relevant warning.


d. Air carrier’s operation of flights at times different from the allocated slots (OFFSLOT):

In case of a misuse, a warning will be sent as soon as the first misuse takes place immediately after data processing. Five (5) working days will be granted for justification and fourteen (14) calendar days for corrective actions. In the event of non-compliance, the case will be forwarded to the Civil Aviation Authority for further appropriate actions.


e. Aircrafts with different seat capacity: 

Each aircraft capacity discrepancy will be reviewed on a case-by-case basis. The monitoring department of HSCA will forward the proven misuses to the Civil Aviation Authority for further appropriate actions.