SCR Crash Course


Slot Coordination Switzerland is glad to provide some basic information and message examples for customers who are new to the airport coordination business, not familiar how to deal with coordinated airports, or have to send an SCR only once in a while. For full and detailed information we kindly ask you to carefully study chapter 6 of the IATA SSIM (Standard Schedules Information Manual). Chapter 6 describes the procedures for using a variety of airport clearance messages (SCR, SIR, SAQ, WIR etc.). These are defined standard message formats used to obtain clearance for, or provide information of, arrival and departure times at coordinated airports. The chapter 6 includes the principles for information exchange, technical specification, and examples. Please visit IATA's website to learn more about this manual, and how to order it.

The following information does focus on the airline's view and on the basic SCR (Slot Clearance Request/Reply) message since this is the main communication for slot allocation between airlines and coordinators.

Main Principles and Rules

  • All dates, days and times are in UTC.
  • For a given flight designator and date at a specific station, there can only be one scheduled arrival and/or one scheduled departure time cleared.
  • Coordinators will respond to slot allocation requests within a period of 3 business days.
  • Clearance offers from coordinators to the airlines are valid for 3 business days only.
  • When a coordinator requires fillings as turnarounds or when airlines elect to file flights as turnarounds (i.e. arrival and departure in a single data record), any modifications pertaining to either the arrival or departure require all unchanged elements to be repeated in order to maintain the turnaround link. (...) If flights are originally filed using an over-midnight indicator, any subsequent change should again be filed using the turnaround format.
  • If apron occupancy and/or terminal capacity are coordinated, the aircraft subtype code must be specified and transit/turnaround format must be used.
  • The SSIM chapter 6 formatted messages must be plain text placed directly in the email body. No attachments, signatures with logos or special characters should be used. Any text following the data lines must start either with GI or SI and the sender's email address has to be repeated on the second line of the message header (IATA SSIM chapter 6.2.1).
    Please observe that coordinators may not accept requests sent from free email accounts!

source: IATA SSIM Manual Chapter 6.2

"SCR Crash Course" including message examples (PDF)