SCR Crash Course

Introduction
Airport Coordination Netherlands does provide on this site some basic information and examples for customers which are new in the airport coordination business, not familiar how to deal with fully 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 telegraph message formats used to obtain clearance for, or provide information of, arrival and departure times at coordinated airports. The chapter 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 (extract from SSIM chapter 6.2)

• Airport slots shall be requested at least 3 working days in advance.
• All dates, days and times are in UTC.
• 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.
• (...) Where apron occupancy (EIN), terminal (RTM), runway capacity or night movements (AMS) are coordinated, the aircraft type code must be specified and transit/turnaround format shall be used
• 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.
• 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.
• For E-mail communication the SSIM chapter 6 formatted message should be plain text placed directly in the E-mail body. No attachments, signatures with logos or special characters should be used.

Message standards
The SCR message consists of 3 parts:
message header, schedule information data line(s) and the message footer.

1. message header:
   

   SCR	message type: SCR = Slot Clearance Request
   /	creator reference (optional)
   S08	IATA schedules season concerned
   22APR	date of message
   AMS	clearance airport concerned

   
    
2. schedule information data line(s):

   N	XY123	XY124	01JUL	30SEP	1234500	120319	CDG	0700	0750	CDG	JJ
   1	2	3	4	5	6	7	8	9	10	11	12

   
    

   1	action code (more information »)
   2	arrival flight designator, number (suffix possible) flight number must consist of min. 3 digits
   3	departure flight designator, number (suffix possible) flight number must consist of min. 3 digits
   4	start of period or single day
   5	end of period or single day
   6	day(s) of operation
   7	number of seats fitted (3 digits) and IATA aircraft subtype (3 alphanumeric)
   8	origin/previous station (arriving from) (IATA 3 letter codes)
   9	required arrival time in UTC
   10	required departure time in UTC
   11	next/destination station (departure to) (IATA 3 letter codes)
   12	arrival and departure service types (may be different)

   
   Important: between the following blocks a space character is mandatory: [2-3-4], [5-6-7-8], [9-10], [11-12] (see also examples)
   Note: Please do not send more than 30 data lines in one SCR message!
    
3. Message footer:
   SI IF NOT AVBL PLS GIVE NEAREST POSSIBLE
GI BRGDS.....
   
   SI = supplementary information (in connection with content of SCR message)
   GI = general information (e.g. greeting)
   
   Note: It is compulsory that any additional text following the data lines starts either with "SI" or with "GI"!

About replies sent by the coordinator
We usually reply to your request as soon as possible (please mind our business hours) but latest within 3 business days. Should we require any special clarification we will inform you accordingly. Should your required time not be available we will provide you with the closest available slot. We appreciate if you reply to our offer within 3 working days. On our offer reply you will find an additional data line indicating the so-called reason code (CA, CD), which will inform you about the main constraint which caused the non-availability of your request. The decoding of these reason codes can be found in the SSIM manual.

Here are a few basic examples (with fake flight numbers) how to compose an SCR message correctly:

• New request in transit/turnaround format, for weekdays 1-5 from July 1 until September 30 (above example):
  
  SCR
S08
22APR
AMS
NXY123 XY124 01JUL30SEP 1234500 120319 CDG0700 0750CDG JJ
SI IF NOT AVBL PLS GIVE NEAREST POSSIBLE
GI BRGDS

• New request for an ad-hoc flight:
  
  SCR
S08
22APR
EIN
NDY998 DY997 18OCT18OCT 1000000 14573G MAN1125 1215MAN CC
GI BRGDS

• New requests for multiple flights (at same airport):
  
  SCR
S08
22APR
RTM
NBA998 BA997 18OCT18OCT 1000000 14573G MAN1125 1215MAN CC
NBA996 BA995 19OCT19OCT 0200000 200752 LGW1525 1615MAN CC
NBA990 BA991 20OCT20OCT 0030000 14573G EDI0800 0850GLA CP
GI BRGDS
• Deletion of a single day flight:
  
  SCR
S08
22APR
AMS
DAF123 AF124 22MAY22MAY 0000060 100142 CDG1520 1600CDG JJ
GI BRGDS
• Aircraft equipment change only:
  
  SCR
S08
22APR
AMS
CMH010 MH011 25APR25APR 0000007 282772 KUL0420 1135KUL JJ
RMH010 MH011 25APR25APR 0000007 398744 KUL0420 1135KUL JJ
SI AIRCRAFT CHANGE ONLY - NO TIME CHANGE
GI BRGDS
  
  Note: a change of an existing cleared slot always consists of 2 lines (C-line and R/L-line)! The C-line ("to be changed") must show the information held by the coordinator, the R- or L-line the new revised schedule information. This well established procedure guarantees that both, airline and coordinator, do change the flights intended only.
• Aircraft equipment change and retiming (no offers acceptable):
  
  SCR
/
S08
22APR
AMS
CLH4123 LH4876 01JUL30JUL 0034507 120319 HAM0700 0750FRA JJ
LLH4123 LH4876 01JUL30JUL 0034507 16873G HAM0730 0820FRA JJ
GI BRGDS
  
  Note: no offers are given, the schedule to be revised will only be confirmed if respective capacity is available. We only recommend to use "CL" if you have absolutely no flexibility in your operation!
  
• Retiming which causes overnight stay:
  
  SCR
S08
22APR
EIN
CEK306 EK307 01AUG01AUG 0000060 048CR1 LJU1910 1950LJU CC
REK306 EK307 01AUG01AUG 0000060 048CR1 LJU1910 05001LJU CC
GI BRGDS
  
  Note: a next day departure requires the "over-midnight indicator" which is placed between the departure time and the next/destination station. The figure 1 does indicate that the departure takes place +1 day after the arrival date.
  Please mind that the start/end period (date) and the day(s) of operation always correspond to the arrival flight!
  
  SCR
S08
22APR
RTM
CJP306 JP307 01AUG01AUG 0000060 048CR1 LJU1910 1950LJU CC
RJP306 JP307 01AUG02AUG 0000067 048CR1 LJU1910 05001LJU CC
GI BRGDS
  
  Note: this is a common mistake when using the over-midnight indicator as also the departure date is included and with above example an additional flight would be requested to arrive on 02AUG and to depart on 03AUG!
• Flight number change, changed routing (new multi-leg flight) and service type change (from regular to charter):
  
  SCR
S08
22APR
AMS
CCX500 CX501 08SEP08SEP 0030000 402744 HKG0420 1050HKG JJ
RCX3600 CX3601 08SEP08SEP 0030000 402744 MNLHKG0420 1050FRAHKG CC
GI BRGDS
• New request with 3letter ICAO code (no IATA code), flight number suffix and mixed service types:
  
  SCR
S08
23APR
RTM
NWLC611B WLC612B 10MAY10MAY 1000000 031D38 INN0440 0600FMO PC
NWLC623B WLC624B 11MAY11MAY 0200000 031D38 FMO1535 1630INN CP
SI BRGDS WLC OPS/ALEXANDRA
  
  Note: we usually clear the airline under its 2letter IATA code. If no IATA code is available or on special request, the flights may be cleared under the 3letter ICAO code.
  
• Acceptance of an offer (no further improvement desired):
  
  SCR
S08
22APR
RTM
ASN015 SN016 22MAY22MAY 0000060 148733 BRU1520 1600BRU JJ
GI BRGDS
  
  Note: we appreciate if you reply to an offer in a separate SCR message!
  
• Acceptance of an offer (maintain on waitlist):
  
  SCR
S08
22APR
EIN
POZ015 OZ016 01MAY30OCT 1234500 148733 BRU1520 1600BRU JJ
GI BRGDS
  
• Decline offer:
  
  SCR
S08
22APR
AMS
ZLX5000 25APR25APR 0000007 230332 CHR1700 K
GI BRGDS
  
  Note: if you decline an offer originating from a new request, you will not hold any slot for this flight! We therefore recommend to always accept our offers (closest available times given) and to revert later again for a possible improvement.
  

Explanations

• IATA schedules seasons
  
  The season code is a combination of either summer or winter season and the year:
  S=summer season, W=winter season, the year shows the last 2 digits (08=2008)
  
  The IATA schedule summer season lasts from each last Sunday in March until each last Saturday in October, the winter season from each last Sunday in October until each last Saturday in March. The calendar year is only
  fully reflected for each summer season, where as for each winter season the year indicated reflects only the calendar year in which the season started (e.g. W07 did last from October 28, 2007 until March 29, 2008).
  
  Important: On January 1 the winter season does not change from e.g. W07 to W08!
  
• Main action codes
   

  Airline		Coordinator
  A	acceptance of an offer - no further improvement desired	H	holding
  C	schedule to be changed	K	confirmation
  D	delete schedule	O	offer
  L	revised schedule - no offer acceptable	P	pending (action or advice)
  N	new schedule	U	unable (refusal)
  P	acceptance of an offer - maintain on waitlist	W	unable to reconcile flight information
  R	revised schedule (offer acceptable)	X	cancellation
  Z	decline offer

  
   
  Note: coordinator's reply code -W- does indicate that the data provided on a C- or D-line is not held by the coordinator or not as such corresponding to the data held by the coordinator.
• Days of operation
  
  Day(s) of operation are indicated with the numbers 1 through 7 in the applicable position for each day of the week with Monday being day 1. Non-operational days are indicated by a 0 (zero) in the applicable position(s) between 1 and 7 (see also examples)
• Main service types
  
  J - Scheduled passenger - normal service
  F - Scheduled cargo/mail
  G - Additional passenger - normal service
  C - Charter passenger
  H - Charter cargo/mail
  D - General/Business Aviation
  P - Positioning, ferry flight
  T - Technical test
  K - Training
  X - Technical stop (e.g. fuel stop)