How to Obtain Common Duty Officers

[Athos]

One of the most valuable resources the Fleet requires in which to complete projects and upgrade facilities for the Fleet Starbase is the Common Duty Officer.  Below are the various methods of which I have found to obtain Common Duty Officers.
 
1.0 Starfleet Academy: Visit the Personnel Officer at Starfleet Academy in the SOL System.  The Personnel Officer is located in the uppermost left building on the grounds at Starfleet Academy.  Each of the below missions takes 2 days to complete and 2 days to cool down.  The missions are as follows:
    1.0.1 General Recruitment: Provides an assortment of personnel, usually 5-7, from common to uncommon duty officers across all categories.  Disadvantage: costs 1000 dilithium.
    1.0.2 Tactical: Provides 2 common duty officers in tactical and/or security
    1.0.3 Engineering: Provides 2 common duty officers in engineering and/or operations
    1.0.4 Science: Provides 2 common duty officers in science and/or medical
    1.0.5 Civilian: Provides 2 common duty officers, both civilian
    1.0.6 There is a random chance to be awarded uncommon DoFFs from these missions
1.1 Grounds of Starfleet Academy: While you are visiting the Personnel Office, you can also visit 3 species specific personnel officers.  These missions are 20 hours and produce 1 DoFF of that species and of common quality.  Note that there is a small chance to score a "Critical" success at these missions where you will be awarded 2 common DoFFs and 1 uncommon DoFF.  The DoFF can be of any division.  There is a 20 hour cool down so you can essentially do these every other day.
     1.1.1 The Andorian and Tellerite personnel officers are speaking with one another behind the building where you find the personnel officer.
     1.1.2 The Vulcan personnel officer is standing in front of the sign for Building 1, near the center of the grounds and near the park that has the emblem of Starfleet Command.
 
2.0 Exchange Duty Officers:  If you have Uncommon, Rare or Very Rare duty officers in your inventory that you do not utilize or want in your inventory, you can exchange them for common duty officers.  Go to the Personnel Officer at Starfleet Academy and select “Exchange Officers”.  By exchanging duty officers, you get a random selection of common duty officers; you do not get to choose what category (tac/sec/eng/ops/sci/med/civ) those common duty officers are. You can accumulate many common duty officers quickly through this exchange as indicated below:
                2.1 Uncommon Duty Officer = 3 Common Duty Officers
                2.2 Rare Duty Officer = 9 Common Duty Officers
                2.3 Very Rare Duty Officers = 27 Common Duty Officers
 
3.0 Additional Methods of Obtaining Duty Officers:

3.1 Asylum: Refugees are useful “duty officers” in that they can be used to gain a higher quality duty officer.  If you have a refugee in your inventory, be on the lookout for “Asylum on XYZ” missions.  Upon completing these missions, you often end up with an Uncommon or Rare duty officer.  If the resultant duty officer is not one that you wish to keep in your inventory, then you can exchange it.
 
3.2 Strike Against Fugitive Support Network: If you score a critical success from this mission, you will be given a Rare Prisoner.  Once you have a prisoner in which to exchange, you must complete the “Exchange Prisoners with the Dominion” mission.  You lose your prisoner, but you typically gain a Rare Duty Officer.  If it is not one you wish to keep, exchange it.  This mission has always been available whenever I’ve had a prisoner with which to exchange.
 
3.3 Caitian Field Flight Training Program: I do not use a carrier so Flight Deck Officers (FDOs) are almost pointless to me.  However, I keep 3 Very Rare Flight Deck Officers on hand to have the best chance of successfully completing the Flight Training Program mission.  Even if you do have a carrier, this method will still apply to you.  This mission will often produce only Green Quality officers, but I have gotten several Rare and Very Rare quality FDOs with which to exchange for Common Duty Officers.  This mission is available every other day.
 
3.4 Instigate Defection: This is a very rare mission.  You can be awarded anything from an Uncommon DOff to a Very Rare DOff.  The resulting DOff usually indicates that they are locked to your character, but you can exchange them for common Doff.
 
3.5 (Species) Officer Exchange Program: These missions are typically available every day but with different species.  I only use common Doffs for these missions and usually end up with Uncommon or Rare Doffs which are then exchanged for common Doffs.

3.6 Support XYZ Nebula Colonization Efforts: These missions can be picked up inside nebulas.  Scoring a Success on this mission will award a Common duty officer.  Scoring a Critical on this mission will award a Very Rare and Common duty officer.



**If I have missed a method that you know of, feel free to post below.  I'll review and update accordingly.
**Thanks for the information Evshell

[Evshell]

Thanks Athos, for this very informative post for the Fleet!

There are 3 additional Duty Officer missions you can do at Starfleet Academy for the 3 non-human founding Federation races.

The Andorian and Tellarite contacts for these missions are directly behind the building where the Personnel Officer is located. The Vulcan contact is in the middle of the grounds and kind of hard to explain, but basically he's near the center circular path, approximately on the west side, I believe.

[Kheren]

Confirmed. To further locate the Vulcan officer; picture the central Academy ground as a compass, the North being the main building where is located the bank, tailor, exchange etc. Therer are four paths leading from the centre where the big Starfleet symbol lies on the ground. You will find the Vulcan female officer standing on the East path, near the center.

As Athos detailed nicely, every Recruitement DOFF task provides officers to use. Recruitement tasks are mostly found daily on Academy and all starbases (ESD, DS9, K7 & Sierra 39).

[Hera]

if you're a Romulan and we need DOffs you can get 4 extra recruitment missions at the new homeworld every couple of days.  Its from a console right by the Captain skill trainer.