NEW YORK ( TheStreet) -- As United (UAL) - Get Report and its pilots continue to dispute the integrity of aspects of the airline's safety practices, the leader of United's pilots said the carrier isn't acting to correct safety problems the union brought to the airline's attention in January.

In a letter to members dated March 12, Jay Heppner, chairman of the United chapter of the Air Line Pilots Association, said pilot leaders met with airline officials on Jan. 28, and "reiterated our long-standing safety concerns that we believe are directly attributable to the company's actions or inactions.

"We gave them a two-page list of these concerns," Heppner wrote. "In the last 42 days, the company has yet to make a commitment to a single item we highlighted in that meeting." A copy of the letter was obtained by TheStreet.

Heppner said the items were broken down into categories involving training, flight planning, captain's authority to refuse to operate certain aircraft, standard operating procedures, crew resource management and irregular operations reports filed under the Flight Safety Awareness Program, a safety reporting system.

United responded Sunday in a prepared statement, saying: "At United safety is our top priority and we will continue to work directly with our pilots to ensure the safety of all of our employees and passengers.

"Further, we remain committed to collaborative and effective joint efforts with our union leadership as our safety standards and programs evolve," the carrier said.

The safety dispute surfaced in January, when two top safety officials at United formally warned pilots in a memo after four recent "safety events and near misses." Those events included a pull-up maneuver because an aircraft was too close to the ground and a plane that arrived at its destination with too little fuel.

The letter referred to a principle of aviation safety, that "every pilot must be willing to speak up if safety is in question (and) every pilot must accept the input of their fellow crew members on the flight deck." The authors acknowledged "this is a brutally honest message," but noted: "Bottom line: United is at a critical juncture in its history.

"We are currently seeing a lot of movement in the pilot group, such as retirements, seat movements and new hires that -- while welcome -- introduce significant risk to the operation," the letter said.

The Jan. 28 meeting came in response to the memo, Heppner wrote in his March 12 letter.

In particular, Heppner noted that the only two people who should be involved in a decision not to fly an aircraft on a given flight are the captain and the flight dispatcher.

 "While we have made progress in this area at many bases, too many chief pilots or their representatives still insist on inserting themselves in the process," he wrote. "Captains must not fear repercussions for actions related to safety, and flight operations must understand that a refusal comes after the risk assessment has been completed by the person responsible for doing so, the captain."

 A United pilot who asked not to be named said the concern reflects cases where chief pilots "are pressuring, harassing, intimidating, coercing, threatening captains into taking aircraft the captain deems unsafe." The pilot referred to the practice as "pilot pushing,' which occurs "when they put schedule and economics" ahead of safety.

This article is commentary by an independent contributor. At the time of publication, the author held no positions in the stocks mentioned.