Separation & Airspace Safety
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Separation & Airspace Safety

Separation & Airspace Safety is a vast domain at the crossroad of many topics: separation standards, safety risks analysis, collision modelling, advanced mathematics and many more.

As far as Air Traffic Control is concerned, it normally starts with national authorities laying down vertical and horizontal separation standards to facilitate the safe navigation of aircraft in controlled airspace. Observance of these standards ensures safe separation from the ground, from other aircraft and from protected airspace. Separation standards may sometimes serve to reduce exposure to Wake Vortex Turbulence although there are many occurrences of significant wake vortex encounter at separations much greater than prevailing minimum separation.

National separation standards are based on the provisions of ICAO Doc 4444 (Procedures for Air Traffic Management), especially Chapter 5. Differences from these standards (if any) are published in national AIPs. The methods used to achieve separation are varied and complex, depending on the phase of flight and the relative trajectories of the aircraft involved (Skybrary, 2019), but they are generally classified in three categories: vertical, lateral, and longitudinal separation.

Separation can be achieved by distance or time reports and/or estimates (commonly referred to as procedural separation) or can be achieved through electronic means such as radar, ADS-B or multilateration (M-LAT) (commonly referred to as surveillance separation).

 

 

A SHORT HISTORY OF THE ICAO SEPARATION AND AIRSPACE SAFETY PANEL

With the advent of commercial turbo jet aircraft operating at high levels and the need to re-evaluate the vertical separation minimum used at that time, the Vertical Separation Panel (VSP) was created in 1954. Later on, the need to review other separation minima due to the fuel shortage in the 70s generated the need to expand the tasks of the Panel and in 1971 the Review of General Concept of Separation Panel (RGCSP) met for the first time. The Air Navigation Commission agreed in 2000 that the Review of the General Concept of Separation Panel (RGCSP) be changed to the Separation and Airspace Safety Panel (SASP). The Commission considered that the change of the panel would better reflect the broad scope of the panel’s work programme and provided an appropriate emphasis on ICAO’s primary objective to ensure airspace safety while improving efficiency of operations. (ICAO, 2014)

 

Separation Concept

In summary, is the concept of keeping an aircraft outside a minimum distance from another aircraft to reduce the risk of those aircraft colliding, as well as prevent accidents due to secondary factors, such as wake turbulence. Separation can also apply to terrain, obstacles, and controlled airspace, wherein an aircraft must stay at a minimum distance from a block of airspace.

Air traffic controllers apply rules, known as separation minima, to do this. Pairs of aircraft to which these rules have been successfully applied are said to be separated: the risk of these aircraft colliding is therefore remote. If separation is at risk of being lost between two aircraft, they are said to be in a conflict.

When an aircraft passes behind or follows another aircraft, wake turbulence minima are applied due to the effect of the wingtip vortices of the preceding aircraft on the following aircraft. These minima vary depending on the relative size of the two aircraft. This is acute on final approach with a smaller aircraft following larger aircraft. (Wikipedia, 2020)

What are ATC clearances for?

A clearance issued by ATC is predicated on known traffic. An ATC clearance means an authorization by ATC, for the purpose of preventing collision between known aircraft, for an aircraft to proceed under specified conditions within controlled airspace. The pilot-in-command of an aircraft is directly responsible for, and is the final authority as to, the operation of that aircraft. If ATC issues a clearance that would cause a pilot to deviate from a rule or regulation, or in the pilot’s opinion, would place the aircraft in jeopardy, it is the pilot’s responsibility to request an amended clearance.

Similarly, if a pilot prefers to follow a different course of action, such as make a 360 degree turn for spacing to follow traffic when established in a landing or approach sequence, land on a different runway, take off from a different intersection, take off from the threshold instead of an intersection, or delay operation, the pilot is expected to inform ATC accordingly. When the pilot requests a different course of action, however, the pilot is expected to cooperate so as to preclude disruption of traffic flow or creation of conflicting patterns. The pilot is also expected to use the appropriate aircraft call sign to acknowledge all ATC clearances, frequency changes, or advisory information. (FAA, 2020)

For more information, visit one of the following WIKIFATCA pages:

Separation & Airspace Safety 165

  1. AAS 1.11 “FLY-BY” AND “FLY-OVER” WAYPOINTS
  2. AAS 1.14 SPACE-BASED AUTOMATIC DEPENDENT SURVEILLANCE – BROADCAST
  3. AAS 1.15 CONCEPT OF GNSS-BASED ALTITUDE
  4. AAS 1.21 UNMANNED AIRCRAFT SYSTEM (UAS) TRAFFIC MANAGEMENT (UTM)
  5. ADME 2.1 CONVERGING RUNWAY OPERATIONS (CROPS)
  6. ADME 2.4 SURFACE MOVEMENT GUIDANCE & CONTROL SYSTEMS
  7. ADS-B Operations
  8. Aerodrome – Land and Hold Short Operations
  9. Aerodrome – Converging Runway Operations
  10. Air Traffic Control Separation Monitoring Tool (ASMT)
  11. Air Traffic Control Separation Monitoring Tool (ASMT)
  12. Air Traffic Control Separation Monitoring Tool (ASMT)
  13. Airborne Separation Assurance
  14. Aircraft Flying with ‘Due Regard’
  15. Airspace Design and Procedures Controller Involvement
  16. Amendment to Current Policy on RNAV Procedural Separation Minima
  17. ASAS-TN2 – Airborne Separation Assistance System Thematic Network 2
  18. ATC Collision Avoidance Techniques
  19. ATS – Study Restrictions in the Enroute Environment
  20. ATS 3.15 (ADVANCED) STRATEGIC LATERAL OFFSET PROCEDURES
  21. ATS 3.16 THE USE OF SAFETY NETS IN ATM
  22. ATS 3.18 SHORT TERM CONFLICT ALERT
  23. ATS 3.19 MINIMUM SAFE ALTITUDE WARNING SYSTEMS
  24. ATS 3.21 SURVEILLANCE: IN-TRAIL PROCEDURES ITP
  25. ATS 3.29 MERGING AND SEQUENCING CONCEPTS
  26. ATS 3.32 RECATEGORIZATION OF AIRCRAFT FOR WAKE TURBULENCE
  27. ATS 3.34 TERRAIN AND OBSTACLE CLEARANCE RESPONSIBILITIES
  28. ATS 3.35 TERRAIN AND OBSTACLE CHARTING
  29. ATS 3.36 EMERGENCY DESCENT PROCEDURES
  30. ATS 3.4 STANDARDISATION OF REGIONAL TRANSITION ALTITUDES
  31. ATS 3.42 HELICOPTER OPERATIONS
  32. ATS 3.46 SECTORLESS ATM
  33. ATS 3.8 RADAR MONITORING
  34. ATS 3.9 GLOBAL COMPATIBLE FLIGHT LEVEL SYSTEMS
  35. Blended Airspace
  36. Co-operative Separation
  37. COM 4.11 RADIO MANDATORY ZONES / TRANSPONDER MANDATORY ZONES
  38. Concept of GNSS-Based Altitude
  39. Conspicuity and ATS Surveillance
  40. Cooperative Separation – Transfer of Control Functions to Pilots
  41. Development of Policy on Formation Flights Within Controlled Airspace
  42. Developments in the use of Global Navigation Satellite Systems (GNSS) as an Approach Aid
  43. EATCHIP ATM Procedures Development Sub-Group
  44. Emergency Descent Procedures
  45. En-route Wake Turbulence
  46. General Considerations on the Implact of U-Space Dynamic Airspace Reconfiguration on ATS Units
  47. Harmonised Transition Altitude
  48. Interactions ATC/ACAS
  49. Introduction of RVSM on a Trial Basis in the North Atlantic Region
  50. Investigate Applications of Provision of Area Proximity Warnings
  51. Investigate interactions between Traffic Collision Avoidance System and Mode S
  52. Investigate Minimum Safe Altitude Warning Systems (MSAW)
  53. Investigate Navigation and Surveillance Provided by a Single Position Information System
  54. Investigate Potential Applications of ADS-B
  55. Investigate Route Conformance Monitoring System
  56. Investigation of the Nomenclature used in the Acronyms CIB & CIC
  57. LM 7.1.3 TRANSFER OF CONTROL FUNCTIONS – LEGAL ASPECTS
  58. Longitudinal Separation Anomalous Interpretations
  59. Management of Mixed Mode Operations
  60. MLS Operational Procedures
  61. Monitor the Application and Implementation of RNAV
  62. Monitor the Developments in the Operational use of ASAS
  63. Monitoring TIBA
  64. NATSPG
  65. Off–Set Tracking in the North Atlantic (NAT)
  66. Policy Review: Strategic Lateral Offset Procedures (SLOP)
  67. Produce a Definition of Area Proximity Warning System
  68. Produce a Definition of Conflict Detection Tools
  69. Produce a Definition of Controller Tools
  70. Produce a Definition of Minimum Safe Altitude Warning Systems
  71. Produce Definition of Short Term Conflict Alert
  72. Produce Definitions of “Fly-by” and “Fly-over”
  73. Produce Definitions on Spacing, Separation and Segregation
  74. Professional and Legal Aspects of Downlinking TCAS RAs (TCAS Resolution Advisories)
  75. Radar Monitoring in the En-route Phase
  76. Radar Monitoring Procedures in TMAs
  77. Radio Mandatory Zones / Transponder Mandatory Zones
  78. Rating for Automatic Dependent Surveillance Control
  79. Reduced Vertical Separation Above FL 290
  80. Reduced Vertical Separation Minima (RVSM)
  81. Reduction in Vertical Separation Above FL290
  82. Reduction of Non-radar Separation Standards Using ADS
  83. Removal of Ground Based Aids
  84. Report of Visual Approach Procedures
  85. Responsibility For Terrain And Obstacle Clearance During Weather Avoidance
  86. Review ATS 3.36 – Recategorization of Aircraft for Wake Turbulence
  87. Review Continuous Descent Operations Manual
  88. Review Existing Policy and Develop Further Policy on Simultaneous IFR Operations on Intersecting / Converging Runways
  89. Review Issues in the Application of Cockpit Display of Traffic Information (CDTI) in Advanced Surface Movement Guidance System (A-SMGCS) Operations
  90. Review Issues Regarding ATC Systems Capability to Monitor Relevant Controller Intervention Buffer (CIB) Parameters
  91. Review of Lateral and Longitudinal Separation
  92. Review of Lateral and Longitudinal Separation
  93. Review of LM (Legal Matters) – Professional Policy of the TPM
  94. Review of Policy in Regards to TCAS RA Downlink
  95. Review of Policy on Area Navigation
  96. Review of Policy on Ground Based Safety Nets
  97. Review of Policy on Precision Area Navigation
  98. Review of Policy on Surface Movement Radar
  99. Review of Policy: Non-plannable Level in the NAT-Region
  100. Review of Policy: Resumption of Separation Following a TCAS RA
  101. Review of Policy: Short Term Conflict Alert (STCA)
  102. Review of Provisional Policy – ATM Safety Monitoring Tools (ASMT)
  103. Review of TCAS Policy
  104. Review of WC (Working Conditions) – Professional Policy of the TPM
  105. Review policy of ACAS / TCAS
  106. Review Policy on Formation Flights within Controlled Airspace
  107. Review Policy on Interception of Civil Aircraft
  108. Review Policy on Separation Lateral and Longitudinal
  109. Review policy on Surface Guidance Movement and Control Systems
  110. Review the Issue of ASAS Separation when less than the Relevant ATC Separation, e.g. Radar
  111. Review the Issues Concerning Controller Intervention Buffer
  112. RNAV – Monitoring its Implementation
  113. RNAV Procedural Separation – Amendment of Current Policy
  114. RNAV Procedural Separation – Longitudinal Distance Standard Minima
  115. RNP for Approach and Landing
  116. RVSM
  117. Safety Components in a Separation Minima
  118. Sectorless ATM
  119. SEP 5.1 USE OF 1000FT VERTICAL SEPARATION ABOVE FL290
  120. SEP 5.2 LATERAL AND LONGITUDINAL SEPARATION
  121. SEP 5.3 AIRBORNE SEPARATION ASSISTANCE SYSTEMS (ASAS) AND COCKPIT DISPLAY OF TRAFFIC INFORMATION (CDTI)
  122. SEP 5.4 CONTROLLER INTERVENTION BUFFER
  123. Separation Between Departing and Arriving Aircraft – Cut-off Point (CoP)
  124. Separation Between Units Without Procedural Agreement
  125. Separation in Class E Airspace
  126. SICASP/WG2 Meeting
  127. Simultaneous Operations on Intersecting Runways
  128. Simultaneous Operations on Intersecting Runways
  129. Spacing, Separation and Segregation – Use in Future ATM Systems
  130. Study ADS-B Applications – Used in ITP
  131. Study Advanced Offset Procedures
  132. Study Automatic Dependent Surveillance (ADS) to Update IFATCA Provisional Policy
  133. Study Down Link of Traffic Collision Avoidance System Resolution Advisories
  134. Study Land and Hold Short Operations
  135. Study Merging and Sequencing Concepts
  136. Study Recategorization of Aircraft for Wake Turbulence
  137. Study Remote Towers Concept
  138. Study Reporting of TCAS RAs
  139. Study Strategic Lateral Offset Procedure
  140. Study Visual Separation on Approach
  141. Surveillance – Provide an update on ITP
  142. Surveillance Applications Policy – Applications of Radar Monitoring
  143. Surveillance Applications Policy – ASAS
  144. Surveillance Applications Policy – Review Policy on Radar Monitoring
  145. Surveillance Applications Policy – Review Policy on ADS
  146. Technical Aspects of Medium Term Conflict Detection
  147. Terrain and Obstacle Clearance Responsibilities
  148. Terrain Clearance and Airspace Design
  149. The Development of MLS Continues
  150. The Use of GNSS – ATC
  151. The Use of GNSS as a Runway Approach Aid
  152. The Use of Lateral Offsets
  153. The Use of Lateral Offsets
  154. The Use of Non-flight Plannable Levels in the Nat Region for Contingency
  155. The Use of Safety Nets in ATM
  156. Three Main Systems of Flight Level (FL) Determination
  157. TPM Review – ATS Editorials
  158. TPM Review – ATS (Major Edit)
  159. Transfer of Control Functions to Pilots (Legal Aspects)
  160. Transfer of Separation Functions to Pilots – Human Factors Aspects
  161. UTM (Unmanned Aircraft System (UAS) Traffic Management)
  162. Vertical Spacing Between Controlled and Uncontrolled Aircraft at or near Airspace Boundaries
  163. WC 10.2.9 CO-OPERATIVE SEPARATION
  164. WC 10.7.7 SEPARATION BETWEEN UNITS WITHOUT PROCEDURAL AGREEMENT
  165. Weather Deviation Procedure in Asia-Pacific Region

Last Update: January 28, 2022  

October 27, 2019   1229   superman    WIKI  

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