ELS, EHS & ADS-B (22-05-18)

Question 1

What is Elementary Surveillance (ELS)?

Answer 1

Referred to as basic functionality

automatic reporting of A/C identity

transponder capability report

altitude reporting +/- 25ft

flight status o the ground or in the air

SI code capability (surveillance identifier) technical functionality

datalink of 56bit messages

Question 2

What is Enhanced Surveillance (EHS)?

Answer 2

For A/C with MTOM of >5700kg and max cruise speed >250kts

consists of extraction of additional A/C Downlink Aircraft Parameters (DAP) consisting of:

mag heading; IAS; M; vertical range; roll angle; track angle rate; ground speed; selected altitude

Question 3

What is Automatic Dependent Surveillance - Broadcast (ADS-B)?

Answer 3

An A/C knows its position through GPS and all other A/C positions through TCAS and mode S (SSR)

this data can be sent to ground stations through mode S data link

controller recieves data

provides RADAR like surveillance services

allows precise surveillance with the need for expensive ground equipement