GROUND BASED SAFETY NETS REFERENCE ICAO DOC 4444

GROUND BASED SAFETY NETS REFERENCE ICAO DOC. 4444 CH. 15 -15. 7. 2, 15. 7. 4 papavasileiou-atm 16 1

OBJECTIVES • State the main characteristics of ground based safety nets and their relevance to ATC operations papavasileiou-atm 16 2

Purpose of Safety Nets • To alert controllers to potentially hazardous situations. • To alleviate potential consequences of human error. papavasileiou-atm 16 3

Safety Net Functions • There are three safety nets currently considered: – STCA – MSAW – APW DAIW papavasileiou-atm 16 4

Purpose of MSAW • MSAW is intended to alert situations where an eligible aircraft is, or is predicted to be, flying at an altitude such that there is a danger of collision with terrain/obstacles. papavasileiou-atm 16 5

Purpose of APW / DAIW • APW is intended to alert situations where an eligible aircraft is, or is predicted to be, flying into a region of protected airspace. x x x x HLF 456 300– Protected Airspace papavasileiou-atm 16 6

Purpose of STCA • STCA is intended to alert the controller to conflicts involving at least one eligible aircraft. papavasileiou-atm 16 7

Safety Net Context Basic Functions Surveillance FDPD Recording Environment Data Surveillance Track Data Flight Data SNET Recording Data Meteorological, Airspace and Parameter Data Safety Nets Controller Options Alert Data Status Data Controller Supervisor Options Status Data Supervisor HMI papavasileiou-atm 16 8

Overview • Safety Nets help controllers avoid collisions, controlled flight into terrain and airspace incursions. • Safety Nets are not a controller tool. • Safety Nets are not intended to be a means to increase ATC capacity. papavasileiou-atm 16 9

Safety Net Objectives • To alert all conflicts, terrain collision hazards and imminent airspace penetrations. • To provide adequate warning time. • To minimise “nuisance” alerts. papavasileiou-atm 16 10

Summary of APW and MSAW • APW is relatively simple, requiring restricted airspace regions to be defined • MSAW protection against high ground may be done simply by mosaic cells • MSAW closer to airports may require details of obstructions • MSAW may also consider glide slope papavasileiou-atm 16 11

Summary of STCA • Safety net - not a control tool • Involves progressive filtering of track pairs • Different airspace requires regions in which different STCA parameters may be set • Performance optimisation requires compromises and controller feedback • Unknown aircraft intention is the main limitation of performance • Input of intended levels has a major impact on number of alerts produced papavasileiou-atm 16 12

Example STCA papavasileiou-atm 16 13

Scenario description Ø There are two aircraft, one overflight at BASUM (HHI 123) and another an arrival (EHAM) at ROBEG (HLF 456). Crossing separation at OSN is less than 5 NM. EC was busy. . . papavasileiou-atm 16 14

SCENARIO STCA HHI 123 320 - HLF 456 400 D 260 0 5 10 papavasileiou-atm 16 15

SCENARIO STCA HHI 123 320 - 5 NM ? HLF 456 392 260 0 5 10 papavasileiou-atm 16 16

SCENARIO STCA HHI 123 320 - HLF 456 374 260 0 5 10 papavasileiou-atm 16 17

SCENARIO STCA HHI 123 320 - HLF 456 365 260 0 5 10 papavasileiou-atm 16 18

SCENARIO STCA HHI 123 320 - HLF 456 356 260 0 5 10 papavasileiou-atm 16 19

SCENARIO STCA HHI 123 320 - HLF 456 346 260 0 5 10 papavasileiou-atm 16 20

SCENARIO STCA HLF 456 -HHI 123 17 3. 0 HHI 123 320 - HLF 456 337 260 0 5 10 papavasileiou-atm 16 21

SCENARIO STCA HLF 456 -HHI 123 10 3. 0 HHI 123 320 - HLF 456 328 260 0 5 10 papavasileiou-atm 16 22

FL. 400 FL. 320 1 MIN 2 MIN 5 NM FL. 260 papavasileiou-atm 16 23