Recently, the Port Authority of New York and New Jersey floated the idea of eliminating LaGuardia Airport’s 1,500 mile perimeter rule. Only two major airports in the United States have perimeter restrictions that ban flights beyond a certain distance: LaGuardia and Washington National.

Both National and LaGuarida airports share a common history: both pre-date the jet age. both were constructed with the assistance of the Works Progress Administration, both later proved too small for jet traffic and the boom in air travel, requiring the construction of newer, larger airports.

Today, there are also several characteristics in common: both National and LaGuardia are governed and operated as a part of an airport system (administered respectively by the Metropolitan Washington Airports Authority, also operating Dulles International; and the Port Authority of NY and NJ, operating Newark and JFK airports), both airports are popular with business travelers, and both airports are subject to perimeter rule restrictions that limit the distance of scheduled flights.

The rule first appeared with the dawn of the jet age. National Airport had non-stop long-distance airline service via propellor-driven aircraft, prior to the rise of jets in commercial aviation. However, DCA was not equipped to deal with the different geometry required for efficient operations of jet aircraft. Dulles International Airport, purpose-built for the jet age, opened in 1962. Noise from jet aircraft was a large reason behind the perimeter rule, but part of the reasoning for the rule was to drive jet traffic to Dulles as well.

The first version of the rule, put in place in 1965, limited flights to a 650 mile radius of Washington, DC. This range just barely includes Chicago; airports that already had non-stop service into DCA (such as Minneapolis and Denver) were granted exemptions. Long-distance flights, exploiting the rapidly growing capabilities of jet aircraft, were forced to use either Dulles or neighboring BWI airport.

The perimeter expanded to 1,000 miles in 1981, allowing non-stop service to South Florida, Kansas City, Saint Louis, and others. In 1986, the perimeter expanded again, to 1,250 miles, far enough to allow non-stop flights from Dallas and Houston.

In 1999, Senator John McCain of Arizona campaigned to remove the perimeter rule entirely. As a compromise, Senator McCain’s hometown airline, America West (later merged with US Air, and now American Airlines) was granted new beyond-perimeter exemptions to serve Phoenix and Las Vegas.

In 2012, the FAA granted several new beyond-perimeter exemptions for new flights to Portland, San Juan, and Austin. The FAA was directed to allow these exemptions by Congress as a part of the FAA’s reauthorization.

Each successive modification of the perimeter rule involved direction action from Congress. As a quirk of DC’s status as a federal enclave, both DCA and IAD (despite both being located outside of the District of Columbia) were built and operated by the Federal government, acting in its capacity as the local government for the National Capital. Both airports were the only airports directly operated by the Federal Aviation Administration.

Since then, several conditions changed. In 1973, Congress granted limited home rule to the District of Columbia, thereby differentiating local government services from those provided by the Federal government. In 1987, Congress created (in conjunction with DC and Virginia) the Metropolitan Washington Airports Authority to operate both National and Dulles. The federal government retains ownership of both airports.

However, despite the move for increased local control for the region’s airports, much of the regulation surrounding them is still codified in federal laws and regulations.

Unlike National, LaGuardia’s perimeter rule is entirely self-imposed. The Port Authority imposed LaGuardia’s 1500-mile perimeter rule (with an exception for beyond-perimeter flights to Denver) in 1984 as a means to manage congestion at the airport and force some traffic to either EWR or JFK.

When looking into additional perimeter exemptions for DCA, the Government Accountability Office argued that the potential loss of flights from Dulles and BWI wouldn’t be catastrophic, and additional competition at the most central airport (in this case, DCA) would be good for consumers.

However, both MWAA and the Port Authority are tasked with managing an airport system, not just maximizing value at one particular airport. Data from MWAA shows a strong correlation between additional capacity for beyond-perimeter flights at DCA with reduced capacity for those same destinations at Dulles.

Dulles is now caught in a vicious cycle. To deal with growth in the mid-2000s, Dulles began a series of massive capital improvements to increase the airport’s capacity and address some of the inherent flaws in the airport’s design (e.g. replacing the plane-mate ‘moon buggies’ with the Aerotrain APM). Unfortunately, since MWAA took on these costs domestic passenger numbers are down, thanks to the collapse of Independence Air, the Great Recession, and the merger of United and Continental (making Dulles is no longer United’s primary east coast hub). All of these factors are driving up the cost per passenger for each remaining enplanement at Dulles. Add in the increase competition from new slots at DCA, and Dulles is struggling.

In response, MWAA is not only dealing with falling traffic at Dulles, but with DCA’s growing pains. The Authority’s new use and lease agreement with the various airlines that use the airports includes a substantial capital program over the next 10 years at DCA to accommodate additional passengers. Part of the Authority’s response is to argue vociferously against any additional exemptions to the DCA perimeter rule; however, they are at the mercy of Congress.

The Port Authority might not need to protect JFK to the same extent that MWAA would like to protect their investments in Dulles, but MWAA’s current experience should provide a cautionary tale. Removal of the perimeter restrictions at LGA would certainly produce winners and losers among both airline tenants at each airport and for the passengers that use them; it’s certainly unlikely to decrease passenger loads at LGA. In fact, American Airlines’ president argues that any changes should wait until upgrades to LGA’s terminals are complete so that they can handle additional passengers.

First, it’s also worth remembering the reason for the imposition of the perimeter rule in the first place: managing demand for one particular airport. True, it’s a somewhat crude tool to manage demand (many are already predicting that DCA-style exemptions to the rule is where the PA will end up), and even without the perimeter rule, there are still slot rules to contend with (another tricky subject).

A second challenge is addressing uncertainty: with airport funding dependent on revenues from airline traffic, a small change can have a big impact. Dulles’ capital program has been greatly affected by changes in traffic levels and by mergers in the industry that shift the airport’s importance to their main tenant in an instant. The need for several of the projects (as well as Dulles’ unaddressed capital needs, such as a new C/D concourse) stems from the airport’s original design, unable to foresee the changes in security requirements, airline boarding practice (jet bridges instead of plane mates), or airline business models (deregulation, leading to the adoption of the hub and spoke model, requiring large concourses for transferring passengers). Dulles was planned and built for the jet age. The original decisions on runway geometry and airfield characteristics have proven to be very accurate; the decisions based on predictions about the behavior of both passengers and airlines has been less successful.

Finally, there’s the need to manage the behavior of two different kinds of users: passengers and airlines. Look at the comments in just about any thread about DCA’s perimeter rule and you’ll find plenty of frequent flyers arguing against the rule. Yet, MWAA can’t successfully implement any changes to their airports without the cooperation of their tenant airlines, acting based on their own set of incentives and preferences. In asking about DCA’s ideal role in the DC region, David Alpert asks:

Should DCA be a sort of niche airport with smaller planes to many little destinations, or an airport that tries to serve as much of the travel demand, close in to the center of the region, as possible? There’s no obvious answer.

Not only is the answer not obvious, but the question itself is more complicated: an airport’s role is only as good as the service that airlines provide; the economics of the kinds of service airlines can provide at any given airport will depend a great deal on a number of factors: airport capacity, costs per enplanement, demand for travel, location/role in an airline’s network, etc.

Shifting an airport’s role can’t be imposed on the airlines; it takes a partnership.