distress signal
From Trekipedia
![](/mw/images/thumb/5/53/alert_red-tos02.jpg/350px-alert_red-tos02.jpg)
Red alert[1]
"Old style" distress signals were keyed to cause interference and attract attention. When the U.S.S. Enterprise NCC-1701 intercepted an old style distress signal in 2254, it caused the ship's systems to react as though a solid object was approaching, setting off collision warnings and the red alert klaxon.[2]