and they will "INVITE" all other planes in vicinity to NUDGE U
ALSO...
seriously, that is what ATC do when they don't have a response frm
a plane ,and after a SELCAL is not PING back , they will ask other
planes in vicinty or same airways & heading to contact the said
plane before declaring an INCERFA. ( uncertainty phrase).
INCERFA is phrase 1 of a SAR ( Search And Rescue ) process.
SELCAL : SELective CALling, a High Frequency mode of kinda paging (
non verbal ) like using a 4 letter code to PING a plane for
response. In the flightdeck, crew will hav chime n lights alert n
pick up the frequency n responsd. usually use for long range
communication over oceans, out of VHF radar verbal coverage. e.g
Pacific , South CHina sea, atlantic ocean, deserts...