The city teachers union is accusing the elite KIPP charter school network of waging an intimidation campaign against teachers who are trying to unionize. The dispute began in January, when teachers at a Brooklyn KIPP school shocked the charter school world by petitioning to join the powerful United Federation of Teachers.

At the time, Dave Levin, KIPP’s cofounder and the superintendent of its New York City schools, indicated that he was open to working with the union — even though many KIPP supporters oppose working with unions, which they argue block schools’ ability to teach at-risk urban students by imposing strict work rules on schools. (KIPP stands for the Knowledge is Power Program.)

Now, the union is accusing Levin of urging teachers not to unionize and painting a bleak picture of what will happen if they do. The accusations are cataloged in two complaints the UFT sent to the state labor board in the last nine days arguing that KIPP is improperly blocking teachers’ ability to unionize. The latest complaint, filed Wednesday, adds to complaints first aired in a Sunday New York Times story reporting that KIPP is resisting the teachers’ organizing drive.

The complaints accuse a KIPP human resources official of telling teachers that he is concerned that the Brooklyn school will lose its affiliation with the KIPP network if they organize; they accuse the school’s founding principal, Ky Adderley, of sitting in the hallway every day to monitor teachers, and they accuse Levin of making a rare attendance at a staff meeting to encourage teachers to reverse their decision to unionize.

Levin and a KIPP spokesman did not return telephone messages requesting comment today.

The letters paint a picture of a chilled atmosphere at the Brooklyn school, called KIPP AMP, since the teachers moved to form a union in January. One complaint describes an exchange between Adderley and two members of the union’s organizing committee. “Have you ever gone sky diving? No?” Adderley is quoted as saying while standing near the teachers. “Its [sic] fun to watch the people’s faces after they jump, they think they’re flying but their [sic] really just falling!”

The union argues that these statements and others by KIPP officials violate New York’s Taylor law, which prohibits employers from interfering with workers’ efforts to unionize.

The KIPP AMP teachers’ effort to unionize aroused alarm at charter schools across New York City, most of which are not unionized. Charter schools get the freedom from unions because, though they are public, they operate outside the regular district system. Most charter school leaders cherish their freedom from unions, which they say allows them to take crucial steps like firing employees who aren’t doing a good job, making the school day longer, and paying teachers based on their performance rather than according to a rigid district-wide pay ladder.

The prospect of a charter school in the KIPP network, one of the nation’s most prominent, falling under a union made charter school leaders concerned that others in the city would follow KIPP’s path.

KIPP AMP teachers said they decided to unionize because they wanted to make their school better. They said they want to have a voice in school policies so that they can demand a more transparent evaluation process and more job protection. They said they do not want a traditional teacher contract, with tenure that makes it difficult to fire teachers after three years. Instead, they pointed to a more flexible contract like the one teachers at the Green Dot charter schools in Los Angeles have negotiated. The Green Dot contract replaces tenure with a job security provision called “just cause.”

By the account included in the union’s complaints, KIPP appears to have countered the organizing drive by arguing that forming a union would hurt the teachers. A complaint filed yesterday describes the staff meeting Levin attended last Friday, February 6:

Levin referred to the union representation at KIPP AMP and the staff’s present benefits, i.e, retirement, maternity leave, private pensions, etc. Levin told the employees: “all of that goes away,” “all of that is potentially in jeopardy”. By these statements, Levin pressured employees present at the staff meeting to withdraw their support of the union or they would lose their pension, maternity leave, or other benefits.