Delta (DAL) - Get Report didn't like the letter that five smaller airlines wrote to regulators last month, complaining they don't have enough slots at New York's three airports.

In a letter to the same regulators, Delta said it has spent 46 years and $1.7 billion to build its New York presence and has acquired slots gradually by buying them, leasing them or acquiring airlines that held them.

"The claim that diligent new entrants cannot obtain New York slots is a myth," wrote Peter Carter, Delta executive vice president and chief legal officer, in a recent letter to U.S. Transportation Secretary Anthony Foxx and Michael Huerta, Federal Aviation Administration administrator.

A month ago, five carriers -- Alaska, Allegiant, Frontier, Spirit and Virgin America (VA)  -- wrote to the same two officials, expressing support for efforts to reform existing slot management strategy. Slots are takeoff and landing times assigned at a handful of congested airports, including the three New York airports: Newark, LaGuardia and Kennedy.

Carter said the Transportation Department should generally preserve its existing slot strategy, which "ensures that slots can continue to be allocated to their most efficient use through unrestricted market transactions."

Carter's letter makes three key points.

First, Delta didn't receive its New York slots free, as the letter from "the complaining airlines" declared. Rather, Delta began LaGuardia service in 1969 with just six slots and has built its slot portfolio so that it now holds about 45% of all LGA slots as well as about 37% of all JFK slots. Each airport has about 1,200 slots. Delta has acquired slots from a dozen airlines including Northeast, Northwest, Pan Am, and TWA.

"It took 17 years for Delta to acquire its first 60 slots at LaGuardia," Carter wrote. "We did not pass the 100-slot market there until 1991 when Delta purchased the Pan Am Shuttle." In 2011, Delta acquired 132 LGA slot pairs from US Airways for $66.5 million and 42 slot pairs at Washington National. Also, Delta has spent $1.5 billion to improve its facilities at JFK and $230,000 to improve at LaGuardia.

A second point in Carter's letter is that some new entrant carriers have in fact obtained access to the New York airports.

JetBlue

has built a major presence at Kennedy since it began flying in 2000.

Southwest

has 51 daily peak day departures from Newark and JFK, and four of the five complaining carriers operate at a New York airport.

Virgin America, one of the five, "is not even using all the New York slots it already has," Carter wrote. Rather, it has transferred four LaGuardia slots to JetBlue and two Newark slots to Porter Airlines, a Toronto-based carrier that flies Bombardier jets. 

Virgin America spokesman Dave Arnold said the carrier is honoring a pre-existing lease deal with Porter Airlines at Newark and does not yet have enough aircraft to utilize all of its slots at LaGuardia.

Carter's third point is that contrary to a claim in the letter from the five carriers, Delta doesn't underutilize its slots. While the slots are required to be operated 80% of the time, Delta uses them more than 90% of the time. Also Delta serves 34 small-and medium-sized communities that do not have service from any of the five.

"These complaining carriers are free to choose their business models," Cater wrote. "And so is Delta."

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