“Condition Green” is standard operating condition on a starship, with power distribution and generation on full, non-critical activities allowed, with requests for additional resources routed through Ops. Most episodes of Star Trek spend most of their time in “Condition Green” and it’s not really seen on screen. The closest you will get is in Star Trek 3, on the bridge of the Excelsior, the light for “Situation Normal” is green.
The two battle conditions escalate in preparedness.
Yellow Alert automatically energizes the shields but not the weapons systems. It brings all tactical sensors online, and alerts the current duty shift of a dangerous situation. Yellow Alert can be left in place over long periods of time. For example, when investigating an asteroid belt or the like. Unfortunately I don’t have any canon references on hand.
Red Alert automatically energizes the shields and weapons systems, bringing all tactical sensors online, and alerts all shifts to go to battlestations (even people who may be currently sleeping, an interesting thing to think about when you see a ship casually throw itself into Red Alert). Impulse engines go to full power generation as well as the warp core; Structural Integrity and Inertial Control fields go to full power. Transporter rooms are fully staffed. Basically, everything on the ship is turned on except for non-critical power drains, and everyone is awakened and put into a duty situation.
In “real life”, you have to be concerned with fuel consumption, crew fatigue (you just woke everyone up to run to fire control or damage control or whatever), and “cry wolf” effects on your crew (you want them at peak alertness, not weary from hours of Red Alert with nothing happening).
The other side effects including the above for these alert modes can be found in the Star Trek TNG Technical Manual. Some of the “automatic” features of the alert levels are features starting with the Galaxy Class; for example, Kirk orders Yellow Alert when the Reliant approaches in Star Trek 2, yet the shields are down. In TNG, the shields would have gone straight up unless countermanded by an order. “Yellow Alert, Mr. Worf, but keep the shields down.”
“Blue Alert” or “Condition Blue” is used for any non-standard mode on a starship, and the exact effects of “Condition Blue” depend on that starship. For example, The USS Defiant’s cloaking device activated “Condition Blue” on the Defiant, letting the crew know to keep electromagnetic emissions to a limited level, reducing various power modes to the engines, etc. According to the DS9 Invasion! novel, the Defiant could pipe it’s waste heat into internal heat sinks to keep it’s profile down. On the other hand, Voyager’s “Condition Blue” involved landing cycles, as the ship was intended to land on planets as required.
Note that some things which may be considered “Condition Blue” never show up as such; saucer separation in TNG and the Multi-Vector Assault Mode in Voyager’s Prometheus class could be considered “Condition Blue” modes, except they usually happened while already at Red Alert.
Double Red Alert
Ironically, there are two stories in TOS where “Double Red Alert” existed; the one story where it may have made sense had “Double Red Alert” edited out, while the one where it was unnecessary had it left in. In “Conscience of the King” Kirk orders a “Double Red Alert” when a phaser set on overload is discovered; the idea is that a “Double Red Alert” is a regular red alert, but immediate, decisive action is required. Frankly, a “Red Alert” with an “Evacuation Order” would have worked better. In the novelization of “Court Martial,” the hangup point for the Court Martial was on if Kirk ejected the pod containing an officer BEFORE or AFTER “Double Red Alert” was called. The idea was that a ship going through an Ion Storm would already be at “Red Alert”, so they needed something “More Important.” The episode was re-written to simply use regular “Red Alert.”
Finally, “Condition Grey” is a low power mode that appears in Voyager’s Year of Hell. Basically, everything that can be turned off is turned off, and strict recycling is enforced. The condition doesn’t refer to specific warning lights but to the lower light levels on the ship involved. One problem I’ve always had with Voyager’s “Condition Grey” is everyone feeding their personal objects into replicators for “Recycling.” Replication is very power intensive, and the “breakdown” process isn’t any less power intensive than the “construction” process. According to the TNG technical manual, waste is stored in tanks for reconstruction by the replicator, but Voyager implies that the items must be immediately broken down by Replicator, a vast waste of resources. (But then again, Voyager hasn’t been known for it’s logical application of the Star Trek universe rules).
Black alert, otherwise known as alert condition black, was an alert signal used on the USS Discovery and the USS Glenn in 2256 to signify that the ship was operating its experimental spore drive. (DIS: “Context Is for Kings“, “The Butcher’s Knife Cares Not for the Lamb’s Cry“)
Battle stations was a general alarm used in naval operations (such as those that influenced the policies of Starfleet) when a starship was going into battle. On Federation starships, a battle stations alarm was usually made in addition to a red alert or, earlier, tactical alert alarm.
On Deep Space 9 and the USS Defiant, personnel carried type 2 phasers while a battle stations alarm was in effect. This practice was also adopted on the USS Enterprise-E by 2379. (DS9: “The Way of the Warrior“, “Call to Arms“; Star Trek Nemesis)
An evacuation alert, or evacuation alarm, was used to signal a mandatory evacuation of a certain deck, ship, planet, or starbase. It was normally used during a catastrophic event such as a hull breach or a loss of antimatter containment. This was a higher alert state than battle stations or red alert. (DS9: “Visionary“, “Valiant“; VOY: “Dreadnought“, “Deadlock“, “Year of Hell“; Star Trek Into Darkness; Star Trek Beyond)
General quarters was a command to prepare for battle that dated back to early naval tradition.
By the 23rd century, the term had been adopted by Starfleet for use aboard Federation starships as a stage of red alert to describe a ship’s condition of maximum readiness. The general quarters order was typically issued as a call for all hands to man their battle stations, but could also vary in state by a number of conditions. By the late-24th century, usage of this alert was phased out in favor of more specific alerts for various situations, such as yellow alert, red alert, security alert, and intruder alert.
Conditions of general quarters Edit
- Security Condition Three indicated that ship’s security had been compromised and an intruder was aboard the ship. This was otherwise known as “security alert three” or “intruder alert”. (TOS: “The Man Trap“, “Dagger of the Mind“, “The Lights of Zetar“) General quarters was sounded under this security condition in 2366 on the USS Enterprise-D. (TNG: “The Hunted“, “The High Ground“)
- Security Condition Four ordered all halls to be sealed off and all weapons to be accounted for and locked away on all levels of the ship. (TOS: “The Man Trap“)
- Alert Condition Baker Two was an alert used on Starfleet vessels when confrontations among the crewmembers on a starship increased to the point where security became involved. In 2266, the crew of the USS Enterprise were under the influence of polywater intoxication. Security reported to Lieutenant Uhura that incidents among crew members of the Enterprise were growing. First Officer Commander Spock had Uhura declare Alert Condition Baker Two over the ship’s intercom. (TOS: “The Naked Time“)
Intruder alert was an alert status on Federation starships and space stations. It could be declared at any time, by computer or any crewmember upon detecting an intruder on board. It could also be activated automatically based on predefined criteria, such as entering a restricted area. The alert was announced by audio and crewmembers were expected to take appropriate action. In 2266, a security alert 3 announced a possible intruder aboard a vessel. (TOS: “Dagger of the Mind“) Intruder alert was also known as “general quarters security condition three”. (TOS: “The Man Trap“)
In 2364, Wesley Crusher, while sitting in the command chair on the USS Enterprise-D, flipped open a control panel and told Captain Jean-Luc Picard of a perimeter alert when an alien entity approached Deneb IV. When Picard ignored him, Lieutenant Worf informed him of the same alert. (TNG: “Encounter at Farpoint“)
In 2256, in a binary system on the edge of Federation space, while on a space walk; Commander Michael Burnham‘s thruster suit‘s computer voice informed her of a proximity alert, alerting her to the danger of a Klingon torchbearer. (DIS: “The Vulcan Hello“)
A security alert was a type of alert signal aboard starships and space stations, primarily for internal security purposes. It was similar to an intruder alert, and could be initiated explicitly by personnel or triggered by predefined parameters.
In the 23rd century, a security alert aboard Federation starships was part of the general quarters alert, and had at least three levels. (TOS: “The Man Trap“, “Dagger of the Mind“) By 2285, security alerts of Federation starshipsystems such as the Constitution-class were separated from the general quarters alert. (Star Trek III: The Search for Spock)
A standby alert was a type of alert signal used to prepare a starship against possible threats. It was similar to an intruder alert. The alert could be called by departments, as was the case in 2267 when Captain James T. Kirk put all departments except for weapons on Standby alert when the USS Enterprise was alongside the SS Botany Bay. (TOS: “Space Seed“)
Tactical alert was a security protocol instituted by Malcolm Reed under the influence of dangerous mind-affecting radiation aboard Enterprise NX-01, in response to the perceived number of threats that were being encountered by the starship in their deep space exploration mission. The protocol was kept due to its usefulness. It was a precursor to the color-coded alert system used on later Starfleet vessels.
The alert was designed to automatically bring the ship to battle-ready status when a pre-programmed set of circumstances occurred (for instance, an impact to the hull, or an order from the captain). When a tactical alert was initiated, the hull plating was polarized, the weapons were automatically charged, and critical systems such as the warp core were secured. In addition, all crewmembers would report to battle stations upon initiation of the alert. The tactical alert was initially accompanied by a loud, grating klaxon, which aggravated Captain Jonathan Archer and Commander Tucker, who felt it sounded like “a bag full of cats.” The klaxon was not retained in future uses of the alert. While in the process of naming the new condition, the terms “security protocol” and “condition red” were suggested. The term “Reed alert” was sarcastically suggested by Commander Tucker as the name for the new tactical alert system Reed was working on, but was later dismissed by Lieutenant Reed as being “a bit narcissistic,” whereas security protocol was deemed “not very dynamic.” (ENT: “Singularity“)
Fire alert was an alert status aboard Federation starships in the 23rd century designated to prepare the crew for possible fires aboard the ship, usually caused by damage to ship systems during battle or other situations.
In 2265, Captain Kirk ordered all decks to go to fire alert when the USS Enterprise passed through the Galactic barrier, as the phenomena they were experiencing was causing circuitry blowouts to the ship’s systems. (TOS: “Where No Man Has Gone Before“)
All information ‘borrowed’ from Memory Alpha