Mayor Vince Gray announced today one of his biggest job initiatives so far: hiring 300 new cops.

The mayor set aside the money to hire the police back in June. Apparently now it’s go time, as the Metropolitan Police Department is gearing up to restart a police academy that’s been dormant since February, according to FOP boss Kris Baumann.

MPD has been calling recruits this week, asking them to drop everything and get ready for an academy class that’s set to start on Tuesday. The city plans to run 25 to 35 recruits through a six-month academy, with new classes starting every month, until 300 new cops are hired.

“The hiring of these new officers will permit us to fill positions vacated due to retirements and other departures while also adding 120 new officers to get the size of the police force up to 3,900 sworn officers by the end of the 2012 fiscal year,” the mayor said in a statement.

But those numbers don’t add up with the data that’s currently out there. Even more notable is that D.C. is still headed for a prolonged period of having a police force dip below 3,800—a level Police Chief Cathy Lanier has said means “trouble”— despite the new hires.

Let’s start with what we know: currently there are 3,805 sworn officers, according to the police department. And the monthly attrition rate is generally accepted to be about 15 cops a month.

That means police levels will be below the “trouble” line for the next ten months. The first recruit class won’t graduate until early April. If the department loses 15 cops a month, then staffing levels will have fallen to about 3,715 officers by the time that class graduates. Assuming everyone who starts the first  academy class graduates (which seems like a big if), then in April the staffing levels will be at about 3,750.

Add twenty new officers per month (35 maximum newbies minus 15 attritioners)  and staffing levels won’t break 3,800 until July of 2012. And if we continue that trend there will only be about 3,850 officers by the end of fiscal 2012, not the 3,900 the Gray administration promises. (Sorry for all the numbers. If LL remembered how to make a pretty graph, he would have done so.)

The numbers only get worse when you factor in that some academy classes will only start with 25 recruits, there will likely be people who drop out of the academy,  and there’s talk that the actual attrition rate of current officers is higher than 15 a month. LL’s reached out to Deputy Mayor Paul Quander for help with the math and will update as needed.

Update. Mayoral spokeswoman Linda Wharton Boyd writes:

“MPD anticipates that most classes will have 30 recruits. However, it is important to note that recruit officers are counted and paid as part of MPD’s authorized sworn strength. After a period of initial training, recruits often take part in some police activities. Ideally, in order to maintain a strong and stable workforce, MPD would have recruits in the Academy every year. The 300 recruits being hired in FY12 are a vital step in maintaining a strong Department and ensuring public safety.”

Okay, fair enough. When you count recruits, the mayor’s math works out. The only problem is: recruits aren’t sworn officers. LL asked, and MPD spokeswoman Gwendolyn Crump says recruits take an oath to be a police officer “upon graduation from the academy.”