Garmin GDL 88 User Manual

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190-01122-03  Rev. A
GDL 88 ADS-B Transceiver Pilot’s Guide
4.2.2 
GDL 88 Integration with TCAD/TAS/TCAS I
Installations with the GDL 88 interface to a TAS/TCAS/TCAD traffic system 
require a display to be installed.
Figure 4-4  GDL 88 With TCAS Not In Ground Station Coverage
When an active traffic system is interfaced with a GDL 88, the GDL 88 receives 
traffic from the active traffic system and attempts to match (or “correlate”) this 
traffic with ADS-B traffic that the GDL 88 has received and is already tracking.  
When a correlation is made, the active traffic system or ADS-B target with the 
most accurate information is displayed to the flight crew. Any active traffic system 
or ADS-B traffic that is not correlated will also be displayed for the flight crew. The 
correlation of traffic by the GDL 88 ensures that only the most accurate, and no 
duplicate, traffic targets are displayed for the flight crew’s situational awareness. 
When interfaced to a TAS or TCAS system, traffic alerts are provided as follows:
Traffic 
Correlated?
TAS/TCAS 
Alert Active?
CSA Alert 
Active?
Aural Alert Source
Visual Alert Source
Yes
Yes
N/A
TCAS/TAS
TCAS/TAS
Yes
No
N/A
None
None
No
Yes
Yes
TCAS/TAS (prioritized) 
GDL 88
TCAS/TAS 
GDL 88
No
No
Yes
GDL 88
GDL 88
Table 4-1  TAS/TCAS Traffic Alerts