Interfaces between {HEAD ~ the segments} include cellular type links 127, 129 between {TAIL ~ users} and aircraft and feeder links 137, 139 between aircraft and ground stations 
Interfaces between { HEAD ~ the segments } include cellular type links 127 , 129 between { TAIL ~ users } and aircraft and feeder links 137 , 139 between aircraft and ground stations
OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH