Emergency Command Hologram
The Emergency Command Hologram (ECH) was a holoprogram developed and implemented by the crew of  while it was in the Delta Quadrant in the 2370s. It was an extension of the Voyagers Emergency Medical Hologram to include strategic and tactical data in order to function in a command capacity in the event of the current command crew being incapacitated during an emergency. ()

Premise 
The idea of an emergency replacement for Voyagers commanding officer, Captain Kathryn Janeway, was first implemented in 2371, after the ship encountered the Komar, a species of non-corporeal trianic-based energy beings. When it was determined that they could take over any organic being at will, Janeway concluded that "The Doctor is the only person on board we can trust at this moment," and while facing the risk the the alien presence taking over the ship, she concluded that "I can't take the risk that it could take over any of the senior officers." She therefore chose to transfer all of her command codes to The Doctor, "until further notice." 

Although The Doctor thought that they meant he was in command, Janeway clarified that he would "act as a failsafe. If you feel at any time that any one of us are under the influence of the alien, you can countermand our orders and take control of the ship." When asked if he felt up to the task, The Doctor concurred, "Well, of course. I make life and death decisions every day." After stating, "Computer, transfer all command codes to the holographic doctor. Authorization Janeway 841 alpha 65," the seeds for the ECH concept were sown. 

In spite of their good intentions, the Komar was one step ahead, and while possessing the body of Tuvok, while under the guise of reconfiguring the ship's sensor relays, disabled the EMH program, effectively locking out and encrypting his initialization routine. With The Doctor disabled, the command codes reverted back to Janeway, a point Tuvok later indicated, when stating, "if we assume the alien could not take over the holographic doctor, then logically it would try to force the command codes back into a humanoid host." ()

Design 
Essentially, the ECH was designed to be a 'backup captain' which possessed information from all major Starfleet strategic and tactical databases. The ECH could incorporate the data into its plans for controlling the ship. It also had basic engineering skills in order to assess damage when necessary. The ECH could interact with the computer or use any console manually if desired as the captain would. While the computer can be ordered, when possible, to bypass or reroute systems to get the ship working again, the ECH could replace necessary components or otherwise manually repair any system required. ()

The ECH was designed to have access to all areas of a ship, especially the bridge, which was only possible if the ship was outfitted with holoemitters or if the ECH was equipped with a mobile emitter, as The Doctor was. ()

Once activated by a commanding officer, all command codes were automatically transferred to the ECH. At that point, the ECH became the acting captain of the ship. If available, the ECH was given directives from other crew or Starfleet to follow. If necessary, the ECH could function alone, ordering the computer to take any action necessary, such as maneuvering, sensor scanning, targeting and firing weapons, and opening communications. () The command codes also allowed for the ejection of the warp core through verbal command. ()

History 
The ECH was first envisioned by The Doctor after he added a daydreaming subroutine to his program in 2376. His initial request to Captain Janeway was denied, but, after The Doctor demonstrated his abilities in practice, Janeway reconsidered and ordered research into the development of the ECH. () Design and testing would occur for the next several months. ()

Janeway activated The Doctor's command subroutines in a real situation in 2377 when tetryon radiation forced everyone to abandon ship. Shortly after the ship was abandoned, Voyager was attacked by scavengers. He and the computer disabled one ship and evaded the others by hiding in a nebula. He managed to begin repairs, but when Commander Chakotay, Ensign Harry Kim, and Neelix returned from an away mission, life support was not yet online, because it was not an immediate concern to The Doctor. ()

After Chakotay and Neelix sought the rest of the crew, who had been abducted by  criminals, Kim and The Doctor disagreed about who was superior to the other; Kim was a commissioned officer, but The Doctor had information about all of Starfleet's great strategists. In one battle with the Quarren, The Doctor called up information about a Romulan battle from his tactical database, leading him to use a photonic shockwave against the ships, before retreating. In the final battle against the Quarren Harry Kim's plan to sabotage three escape pods and detonate them once in the enemies' tractor beams saved Voyager. This provided a lesson to The Doctor about experience. He realized that he was needed on Voyager as a medic more than as a commander, and made peace with Kim before handing back command to a rescued Captain Janeway. ()

A trial on the rights of The Doctor was initiated when his holonovel was published without his permission in 2378; the publisher arguing that The Doctor had no legal rights due to his status as a hologram, prompting the crew to arrange a hearing to determine The Doctor's rights as a sentient being. Harry Kim cited the ECH extension in The Doctor's favor, regarding it as a Human desire to develop and change. While the publisher argued that this simply showed that The Doctor's program could be altered, Harry countered that The Doctor's request for the creation of the ECH represented a desire to improve that would not have been expected of a hologram designed to do a specific task. ()

Later that year, The Doctor disguised himself as Commander Chakotay and used his command codes to transform himself into the ECH. He would later eject the warp core, then escaped from the ship aboard the  with the warp core to exchange it with the Hierarchy for Captain Janeway's freedom. Both Janeway and the warp core were recovered and returned to Voyager, although The Doctor remained in sickbay for a week out of embarrassment about the "deathbed confessions" he had made while the excess subroutines installed by the Hierarchy were being deleted. ()

Appendices

Appearances 
 (mention only)

Apocrypha
The Doctor (played by Robert Picardo) assumes the guise of the Emergency Command Hologram in the Star Trek Online mission "Takedown", when he is given command of a Hierarchy ship during the final battle to defeat a resurgent Vaadwaur threat endangering the entire Delta Quadrant.

de:Notfall-Kommando-Hologramm
fr:HCU
ja:緊急用司令ホログラム
Holographic programs
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