Yellow alert

A yellow alert or condition yellow was the second highest alert signal status on Starfleet vessels, one stage below red alert. It designated a ship-wide state of increased preparedness for possible crisis situations.

In this status, a ship's defense fields were energized, and/or the deflector shields were brought to full power, but the weapons systems remained off-line. Depending on the situation, the captain could order a reduction in the closing speed between itself and any potential incoming threats. 

A yellow alert could either be activated manually by the commanding officer in preparation for a tactical or environmentally hazardous situation, or automatically upon detection of unknown or hostile spacecraft, or upon detection of certain system malfunctions. If the situation escalated, the commanding officer or the main computer would order a red alert. 

When the hijacked USS Reliant went on an intercept course against the USS Enterprise (NCC-1701), Admiral James T. Kirk ordered a yellow alert. 

Yellow alert was not typically ordered in the Earth Spacedock, however, in 2285, such an order was given aboard the USS Excelsior when Admiral James T. Kirk was stealing the USS Enterprise. 

In the 24th century, Starfleet Regulations still called for a Federation starship to go to yellow alert when targeted by a laser weapon from another vessel. 

In early 2365, when the USS Enterprise (NCC-1701-D) was approaching a void in space, Lieutenant Worf recommended that the ship go to yellow alert. When pressed by Captain Jean-Luc Picard for this recommendation, Worf responded that he was thinking about an old Klingon legend about a large space beast that devoured entire ships when he gave the recommendation. 

Admiral Haden informed Captain Picard that all Federation starships were on yellow alert in preparation for a possible Romulan invasion from Nelvana III. 

In 2369 Commander Benjamin Sisko ordered yellow alert when an unknown vessel from the Gamma Quadrant came through the wormhole. 

The same year Commander Sisko ordered yellow alert when the imaginations of the people aboard Deep Space 9 became reality. 

Captain Benjamin Sisko put Deep Space 9 on yellow alert after learning that the Dominion was about to invade the Alpha Quadrant. 

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