In all other Star Trek series the chief engineer is a Lieutenant or higher

And yet in DS9, a huge installation, the most senior engineer is a Senior Chief Petty Officer, seemingly outranked by everyone, even Nog once he stops being a cadet and receives the rank of ensign:

Why is this? I know that O'Brien's rank is a little unclear through 'The Next Generation' but by the time he arrives at Deep Space 9 that seems to be fully cleared up and the chain of command is clear; O'Brien is outranked by anyone with a name.

Is this because Deep Space 9 is a space station? But in that case why aren't all the ranks lower?

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    Not an answer, but in real life the difference between the lieutenant/commander grades and the warrant/petty officer ones isn't (solely) a matter of level. Chief Petty Officer is an enlisted grade: in other words, he didn't go to officer school (presumably, Starfleet Academy). In the army, he'd be a sergeant-major. – Daniel Roseman Dec 10 '13 at 14:28
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    @DanielRoseman - the point is, as an enlisted, he'd be not the part of the chain of command. A random 3d Lt could order him to do stuff, legally. – DVK-on-Ahch-To Dec 10 '13 at 14:34
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    The real question now is: why was O'Brien wearing command red in "Encounter at Farpoint"? – Xantec Dec 10 '13 at 14:40
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    @DanielRoseman - Going by USN/Army/Marine ranks, he'd be a Master Sergeant (NATO OR-8). Sergeant-Major is equivalent to a Master Chief Petty Officer (OR-9), the next rank up and the top of the enlisted ranks. – Compro01 Dec 10 '13 at 15:44
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    “yet in DS9, a huge installation, the most senior engineer is a Senior Chief Petty Officer” — it might be worth noting that when the Federation crew for Deep Space Nine was assigned, it was essentially a humanitarian mission to a far-flung civilisation (the Bajorans) coming out of occupation by Cardassian forces. It wasn’t exactly a big strategic priority for Starfleet. It was only the discovery of the wormhole that made DS9 more high-profile. – Paul D. Waite Jul 11 '16 at 11:29

12 Answers 12


O'Brien isn't low ranked. He's simply an enlisted NCO rather than a commissioned officer.

On the enlisted ranks, he's second from the top, with only a Master Chief Petty Officer outranking him.

While any random officer does outrank him and can give him orders, only a very stupid one would ignore what he says. At the end of DS9, he has been in Starfleet for 29 years, longer than most random lieutenants have been alive. He is the voice of experience and someone who knows his job very, very well.

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    In that case, it's that either Roddenberry changed his mind or other people just simply adjusted things without him noticing. Originally, Roddenberry had the idea for TNG that Starfleet would be all commissioned officers who went through the Academy. This later changed somewhat (e.g. the enlisted rank of Crewman sneaks in in season 4) and goes further in DS9 and Voyager, the latter of which has many Crewmen, going closer to a real life enlisted/commissioned mix. – Compro01 Dec 10 '13 at 16:20
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    The Captain may command the boat (or the space station), but the Chiefs run it. O'Brien is basically chief of the boat on DS9, meaning he has the final say in how things are done. – John Bode Dec 10 '13 at 16:33
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    @Compro01 There were Crewmen present in The Original Series very early on. TNG also had Crewmen mentioned early in the series run. And according to the listing of military ranks a Crewman's equivalent rank in the Army would be Private First Class. So despite any intentions Roddenberry may have had there is a precedent for enlisted men in Star Fleet going back to the beginning of Trek. – 22nd Century Fza Dec 11 '13 at 4:59
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    I had a good friend who joined the Air Force. He went to college, was in ROTC, and when he graduated he was a second lieutenant. He commented to me how odd it felt that he was all of 23, had graduated a few months ago, and had NCOs like Sergeants who had been in the AF longer than he'd been alive saluting him and calling him "sir". So it happens in real life too. – PopularIsn'tRight Oct 12 '14 at 3:06
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    I'm a USN veteran, though I left in 1985. Spent five years enlisted and left as a 2nd class petty officer. I've spent many a watch with an ensign or LT JG in charge but everything was run by the Chief on duty. A junior OIC is usually smart enough to consult with the senior enlisted. If not, he/she will inevitably screw up royally somehow. Most junior officers do not go to an academy. They graduate from college & go through Officer Training School or took ROTC. In any case even the most inexperienced chief has eight years in the military, and they have to be really good to make rank that fast. – Generic Geek Aug 31 '15 at 3:02

O'Brien's rank is essentially irrelevant as long as there's always someone who outranks everybody else who can appoint O'Brien in charge. You might as well ask how Major Kira and Constable Odo can be part of the station's command structure, but not part of Starfleet's chain of command, or how Seven of Nine can have all the responsibilities she has aboard Voyager.

At any moment on DS9 Sisko can give anyone he wants a field commission, including O'Brien and later Kira. He can also take it away. The rules for field rank assignments are very liberal in any highly functioning military, requiring only obedience to a commanding officer and no ceremony at all. If Sisko says a noncommissioned officer is chief engineer and orders his commissioned officers to report to the chief engineer, that's exactly what they'll do.

Picard even makes an 8-year-old girl his first officer in the TNG episode "Disaster," and just in case you think that wasn't serious, recall that he also assigned a teenage boy with no prior experience to pilot the fleet's flagship.

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    Militaries involved in joint operations happen in real life and a command structure is negotiated. But you are right, Sisko could give O'Brien that position and order people to obey him. This would even make some sense as O'Brien stated that he had no interest in being an officer. But this would require Sisko to specifically want O'Brien rather than him being assigned in the usual fashion; but I can't find any common postings between the two – user20310 Dec 18 '13 at 16:55
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    Sisko: USS Livingston, USS Okinawa, USS Saratoga, DS9. O'Brien: USS Rutledge, USS Enterprise, DS9 – user20310 Dec 18 '13 at 16:57
  • Easily put. An admiral could assign him, or Sisko could recognise O'Brien's expertise and experience on the Enterprise as invaluable – user001 Jul 11 '16 at 10:35
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    The assigning of the girl to be his first officer in "Disaster" was clearly not meant to be serious... – Ham Sandwich Feb 14 '17 at 15:28

could be that O'Brien is a warrant officer and not an enlisted NCO rank. Warrant officers often are technical specialist, at least in the US Army.

  • I can see this as an answer; two routes to a similar position - the Starfleet academy route and the (seemly much longer) technical specialist route – user20310 Dec 13 '13 at 11:16
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    There's no cannon reference to warrant officers in Starfleet, though there has been some confusion. Senior Chief Petty Officer is most definitely an NCO rank in the US Navy, quite high up, and it stands to reason it's enlisted in Starfleet. – Schwern Dec 4 '14 at 18:05
  • How Star Trek represents how a ship is run and how US Navy operates currently, have no relationship with each other. – user71160 Sep 6 '16 at 3:25

In most military and even non-military systems, rank and position are two distinct things.

Although a higher rank implies a higher position or vice-versa, it is not necessary true.

The exact relation depends on the system itself. Inside industry, I have seen people with less than high school degree leading teams of engineers (being section chief). In the military, a Captain can also have the position of Military Unit Commander, but that position itself is usually occupied my a Major or higher (for my country).

Practically, the rank is given by the military system itself and your training/school in the military, while your position is given by job qualification factors. A Chief Engineer does not require or need a very high military rank in order to perform his job admirably.


With enlisted men its more a matter of position then rank, while the chief was of a lower rank than even Nog (I think since he called him sir jokingly) but Nog's position was some low level engineer whereas the chief was chief engineer for DS9 (a position which would have gone to an officer if Starfleet Command knew how important it would become) so it was the chiefs position that gave him command not his rank. DS9 was low priority when it was started thus a commander and not a captain (Sisko), a rookie chief of medicine and a Petty officer for Chief engineer.

The thing about why O'Brien was wearing red and a rank was most likely do to his field commission from the Cardassian war and Picard just kept the commission until it expired at which time he became Chief Transporter Operator...but remember O'Brien was an infantry grunt and crewman who never went to engineering school but was promoted into engineering after proving himself during the Cardassian war.


Another thing to point out is that there is no money in the Federation, thus no pay checks. Someone who's interested in engineering, not command, has no added incentive in officers' higher pay.

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    also there is Starfleet Academy - we see in 'The Drumhead' at least one other Starfleet member (Simon Tarsis) bypass the Academy (and thus officer-rank) and join as an enlisted man because he couldn't wait to get out into space and didn't want to deal with years of school – NKCampbell Feb 14 '17 at 15:52

Chief O'Brien wears Pips denoting the rank of Lieutenant SG. It's entirely possible that he was given a battlefield commission, much in the same was that enlisted men are given them during combat.

Chief O'Brien

Federation Rank Structure Image


Just because O'Brien is a SNCO, doesn't preclude him wearing red, all helmsmen wore command red due to their function aboard ship, not because of a role in the chain of command. By the same token enlisted crew were seen wearing gold (TOS, ENT); or white (Movie era)

  • Also in TOS we saw a JAG officer wearing red (which at the time was the color for operations) and in TNG we saw one wearing red (the color for command and administration); In DS9 we also saw an admiral wearing gold (by then the color for operations, security, and tactical) – Enterprising Voyager Jul 11 '16 at 7:53
  • Just so you know, you can edit your answer, if you want to add the information in your comment to your answer. – Adamant Jul 11 '16 at 8:25
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    I'm not sure I understand how this answers the question. This isn't about what uniform o'brien wears – user20310 Jul 11 '16 at 9:45

I believe that this actually can be traced back to Chief Kyle in TOS, the transporter chief. O'Brien was originally introduced in that particular role, as I recall. Kyle was last seen in the movies holding the rank of LCDR but, as was mentioned previously, O'Brien had no interest in a commission.


Chief O'Brian may be the most famous person enlisted in Star Trek but he's also hierarchically ranked equivalent to a department head. I think the only reason they did this (totally not fan service) because if something goes wrong it's not the career-ender it would be for an officer. The non-main officers give him crap at their own expense.


O'Brian is a tactical officer with engineering expertise. Tactical is part of security and although he is stationed as chief engineer for his expertise. He is still technically an attachment of security ranking below Odo. All security officers report to an officer specifically with a command rank. Science and Security officers may or may not command level experience based on their performance at the academy. All starfleet personnel are required to attend the Star Fleet Academy where they get to choose their path and set their own goals. O'Brian has no desire to be a command officer and since their is no pay difference, and no pay at all... They all work together to better all life... At least that is the story. Crazy right.

  • Interesting! Do you have any sources or quotes? – tobiasvl Mar 8 '17 at 12:11

Coming from active duty in the US Navy, Chief does not necessarily denote a rank. The CHENG (pronounced CHANG) or Chief Engineer is an officer, not enlisted. He/she is never called chief. It is Cheng or sir. A department head is almost always, if not always, an officer. Division officer (Divo) is an officer and is below Department Head. LCPO is Leading Chief Petty Officer and is the highest CPO SCPO or MCPO of a department. They are definitely within a Chain of Command, except they are only above lower enlisted ranks. The MCPOC or Master Chief Petty Officer of the Command is the highest ranking enlisted of a ship and answers to the Captain. He is still subject to an officer giving him a command, but that officer had better be right! I did hear O'Brein get called LT in an earlier episode. Made me think he is the Chief Transporter Officer. Would still never be called Chief!

  • Most of this answer appears to be unrelated commentary on how ranks work in real life. However, the last part about you thinking he was called LT, I'm assuming you mean lieutenant, actually appears to be an answer. Could you edit to focus on that and add in evidence for this such as quotes and episode? – TheLethalCarrot Sep 7 '18 at 10:52

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