Priority one
Priority one was a type of communiqué used within the Federation, including Starfleet, that noted messages of high priority.

In 2257, the  under the command of Christopher Pike made a priority one distress call which was answered by the . ()

In 2269, Uhura sent a priority one call to Governor Bob Wesley of the planet Mantilles to warn him of the danger of an approaching cosmic cloud. ()

In 2285, Captain J.T. Esteban instructed his communications officer to send a coded priority one message for Starfleet Commander. In his message he stated: "Federation science vessel Grissom arriving , Mutara sector, to begin research. J.T. Esteban, commanding." ()

Prime Minister Nayrok sent the  a priority one message on a priority channel, after Roga Danar escaped from the ship and captured an Angosian police shuttle. ()

In 2366, Captain Jean-Luc Picard received a priority one message on a secured channel from Admiral Haden concerning the Romulan defector Alidar Jarok. ()

Later that year, the Enterprise-D's mission to contact the living spacecraft "Tin Man" was classified as priority one. The Enterprise was to observe minimum contact procedures. ()

The same year, Reittan Grax sent a priority one message from Betazed to the Enterprise-D to inform them about the disappearance of Lwaxana Troi, Deanna Troi and William T. Riker. ()

The following year, Captain Jean-Luc Picard had Worf hail Captain Benjamin Maxwell on the  priority one when Maxwell broke away from the Enterprise-D's escort to attack a Cardassian vessel in the hope of proving that it was not a simple supply ship carrying scientific equipment but instead carrying weapons. ()

Later that same year, Data sent a priority one message to Worf ordering him to arrest the brainwashed Geordi La Forge in order to prevent him from assassinating Klingon Governor Vagh. ()

In 2369, the Federation runabout  received a priority one broad band distress signal from the Kobliad transport Reyab. ()

Admiral Nakamura sent a priority one message to Captain Picard in 2370. Worf was ordered by Picard to send the message to Doctor Crusher's office in sickbay. Nakamura informed Picard that he initiated a fleet wide yellow alert, because Starfleet Intelligence has picked up some alarming reports from the Romulan Star Empire. ()

In 2372, Lieutenant Commander Jadzia Dax received a priority one message from Starfleet Intelligence which stated that the Klingons placed Orbital defense systems in Cardassian territory. ()

The same year, Deep Space 9 received a priority one message from Starfleet Security which contained a recording made at the Antwerp Conference that showed an explosion caused by a bomb planted by a Changeling which killed 27 people. ()

See also
Grade 1 priority
Distress call
Priority two
Priority 01