The Scope Clause: The Obscure Rule Shaping US Regional Aviation

Published Aug 10, 2026, 3:00 AM EDT Journalist - Steven has a varied background in communications, and it was this passion for writing combined with his in-depth knowledge of the aviation industry that led him to Simple Flying. A keen linguist, he also has experience in translation and interpreting. Based in Palma, Spain Most airline passengers never think about why one flight is operated by a major airline while another, carrying the same branding, is flown by a regional partner. Even fewer realize that one of the most influential forces behind those decisions is not an aircraft manufacturer, the Federal Aviation Administration (FAA), or even airline management, but a little-known provision buried inside labor agreements. Known as the scope clause, this contractual rule quietly determines which aircraft can serve thousands of routes across the US and has become one of the defining factors shaping the country's regional aviation industry. Although it receives little public attention, the scope clause influences everything from the size of regional jets to the availability of flights in smaller communities. It has affected aircraft development, forced airlines into unusual seating arrangements, and even delayed the introduction of more efficient aircraft. As airlines continue to face pilot shortages and changing economics, this once-obscure labor provision has become one of the most significant constraints on how the US airline network evolves. What Exactly Is The Scope Clause? Credit: Shutterstock Unlike many aviation rules, the scope clause is not a federal regulation or an FAA requirement. Instead, it forms part of collective bargaining agreements negotiated between mainline airlines and their pilot unions. Airlines including American Airlines, Delta Air Lines, and United Airlines all operate under versions of these agreements, with each contract containing detailed provisions that define how much flying can be outsourced to affiliated regional carriers. The purpose is straightforward - mainline pilot unions negotiated these clauses to prevent airlines from shifting flying from higher-paid mainline pilots to lower-paid regional airline crews. Without such protections, airlines would have a strong financial incentive to replace larger numbers of mainline flights with cheaper regional operations, reducing career opportunities and wages for pilots employed by the parent airline. To achieve this, scope clauses impose several restrictions rather than relying on a single rule. The best-known limitations cap regional aircraft at 76 passenger seats and a maximum takeoff weight of 86,000 lb (39,009 kg). They also place limits on the total number of regional aircraft an airline can operate and, in many cases, restrict the proportion of overall flying that regional carriers can perform. These rules vary between airlines but collectively create a carefully controlled boundary separating regional and mainline operations. Why 76 Seats Became The Magic Number Credit: Shutterstock The 76-seat limit has become one of the defining characteristics of the modern US regional fleet. While many regional aircraft elsewhere in the world carry more passengers, US carriers have spent years building their fleets around an artificial threshold created by labor agreements rather than operational efficiency alone. This has encouraged airlines to retire many smaller 50-seat regional jets while expanding fleets of aircraft that fit neatly within the contractual limits. Models such as the Embraer E175 have become enormously successful because they maximize passenger capacity while remaining compliant with scope restrictions. The aircraft offers significantly better economics than older regional jets, allowing airlines to carry more passengers without exceeding the agreed limits. The result has been a gradual increase in the average size of regional aircraft over the past two decades. Airlines have favored the largest aircraft permitted by scope because they provide lower operating costs per passenger while remaining eligible for regional operations. Instead of flying numerous smaller aircraft, many regional operators have consolidated around fleets dominated by 70- and 76-seat jets, fundamentally reshaping domestic air service throughout the US. The emphasis on these larger regional aircraft has also simplified fleet planning, as rather than maintaining a wide variety of aircraft sizes, airlines increasingly concentrate on types that make the best possible use of every seat allowed under the contracts, creating a market unlike almost anywhere else in commercial aviation. The latest data from ch-aviation shows that SkyWest Airlines is currently the world's largest operator of the Embraer E175, with a staggering 263 in its fleet: Ranking Airline Embraer E175 1 SkyWest Airlines 263 2 Republic Airways 178 3 Envoy Air 137 4 Mesa Airlines 60 5 Horizon Air 47 How Aircraft Design Has Been Shaped By Labor Agreements Credit: Shutterstock Perhaps the most remarkable consequence of the scope clause is its influence over aircraft manufacturers themselves. Around the world, manufacturers generally design aircraft to meet airline demand for greater efficiency, improved economics and increased passenger comfort. In the US, however, they must also design around contractual limits negotiated between airlines and pilot unions. No aircraft illustrates this better than the Embraer E175-E2. The Brazilian manufacturer developed the aircraft as an updated version of its highly successful E175, incorporating new engines, aerodynamic improvements and substantially lower fuel consumption. Under normal market conditions, the aircraft would have represented an obvious successor for regional airlines operating the earlier model. However, the Embraer E175-E2 exceeds the maximum take-off weight permitted under current scope clauses by roughly 12,000 lb (5,443 kg). Although it still carries the same number of passengers, its greater weight makes it ineligible for operation by US regional airlines. Since the US represents by far the world's largest market for aircraft in this category, the restriction effectively eliminated demand before the aircraft even entered service. The consequences have been significant, and Embraer has repeatedly delayed and paused development of the E175-E2 because no major US airline can currently place orders while existing scope clauses remain unchanged. In an unusual reversal of normal industry dynamics, a labor agreement rather than technological capability has become the principal obstacle preventing a new-generation aircraft from reaching the market. The Unusual Ways Airlines Comply Credit: Shutterstock Because scope clauses contain precise numerical limits, airlines have occasionally adopted surprisingly creative methods to remain compliant while extracting the maximum value from their aircraft. One of the best-known examples involves American Airlines' regional fleet, operating under the American Eagle brand, where dozens of aircraft technically capable of carrying more passengers have been deliberately modified to stay within contractual requirements. Some regional jets originally built with 76 seats have had individual seats removed or permanently blocked from use. In one particularly unusual arrangement, a table was installed where passenger seats would normally be located, ensuring the aircraft remained compliant with the agreed seating limit while preserving the remainder of the cabin layout. Although this may appear odd to passengers, it represents a practical response to contractual obligations rather than an engineering necessity. These modifications demonstrate how influential the scope clause has become in everyday airline operations. Rather than redesigning entire aircraft or abandoning useful fleet assets, airlines sometimes choose relatively inexpensive cabin alterations that allow them to continue operating within contractual boundaries. Such decisions highlight the economic value attached to keeping aircraft in regional service even when the seating arrangements appear unconventional. The clause also affects long-term fleet planning, lease negotiations and aircraft acquisitions. Every decision involving regional aircraft must be evaluated against scope requirements, meaning contractual compliance often becomes just as important as fuel efficiency, maintenance costs or passenger demand. The Pilot Shortage & Changing Regional Aviation The persistent shortage of airline pilots has further strengthened the importance of scope clauses in recent years. As airlines compete for qualified flight crews, pilot unions have generally shown little interest in relaxing protections that safeguard mainline flying. Strong demand for pilots has reinforced the unions' bargaining position, making substantial changes to scope agreements increasingly difficult to negotiate. Regional airlines have consequently faced mounting challenges in maintaining service, particularly on thinner routes serving smaller communities. Limited pilot availability has forced many operators to reduce schedules, retire older aircraft more quickly, and concentrate resources on routes capable of generating stronger financial returns. Combined with scope restrictions, these pressures have accelerated the shift toward larger regional aircraft while reducing service on lower-demand routes. Communities that once relied on frequent flights operated by smaller regional jets have often experienced declining connectivity as airlines redeploy aircraft elsewhere. In some cases, destinations have lost service entirely because available aircraft and pilots can generate greater returns on busier routes. While many factors contribute to these network changes, scope clauses remain an important part of the equation because they limit the flexibility airlines have when responding to changing market conditions. Higher operating costs have also filtered through the system. Larger aircraft are generally more efficient on a per-passenger basis, but reduced flexibility means airlines cannot always match capacity to demand as effectively as they might otherwise prefer. This creates additional challenges for serving smaller markets where passenger numbers fluctuate throughout the year. The Debate Continues Credit: Shutterstock Supporters of scope clauses argue that they remain essential for protecting professional pilot careers and preventing airlines from undermining negotiated wages through outsourcing. From this perspective, the provisions preserve stable career progression from regional airlines to the mainline while ensuring that larger portions of airline operations remain staffed by pilots employed directly by the major carrier. Given the substantial investments required to become an airline pilot, unions view these protections as a fundamental part of maintaining industry standards. Critics, however, argue that the clauses increasingly constrain innovation and prevent airlines from adopting newer, more efficient aircraft. They point to examples such as the Embraer E175-E2, whose improved fuel efficiency and lower emissions cannot be fully realized because of contractual weight limits rather than technical shortcomings. They also contend that passengers in smaller communities ultimately bear some of the costs through reduced flight options and higher fares resulting from constrained regional capacity. The continuing disagreement reflects the competing priorities shaping modern US aviation. Airlines seek greater operational flexibility, manufacturers want access to the country's largest regional aircraft market, pilot unions remain determined to protect mainline jobs, and smaller communities depend on affordable regional air service. Until those competing interests align, the scope clause will continue to exert an influence far beyond the pages of labor agreements, quietly determining which aircraft enter service, where they fly, and how US regional airline networks develop.