Time Zones and the American Air Traffic Controller

The American air traffic controller workforce is facing a severe crisis, one that impacts the entire National Airspace System (NAS). This report explores the extreme difficulty of the air traffic controller job, the chronic understaffing and fatigue, and the critical role of time management—not time zones, but the human battle against circadian rhythm disruption and Daylight Saving Time (DST). We analyze the staggering cognitive load, the 6-day workweeks, and how the 2025 government shutdown pushed an already strained system to its breaking point. Understanding this crisis is essential for grasping the future of air traffic safety and workforce management.

The Invisible Gauntlet: The Inherent Difficulty of the Controller's Job

Before any systemic stressors are considered, the baseline difficulty of becoming and serving as an air traffic controller is among the most demanding of any profession. The workforce is filtered through a rigorous gauntlet designed to select only a tiny fraction of applicants who possess an elite combination of cognitive, medical, and psychological attributes.

The Needle's Eye: The Rigorous Barriers to Entry

The FAA sets exceptionally high, non-negotiable standards for entry into the profession. An applicant must be a United States citizen and pass a rigorous security investigation.

Most notably, applicants must be under the age of 31 to apply. This "under 31" age limit is a structural bottleneck that severely cripples the FAA's ability to respond to staffing crises. Unlike other high-stress fields, the agency is legally barred from hiring experienced, high-performing 35- or 45-year-olds. It must recruit only from a narrow age band that is simultaneously the most in-demand by every other industry. This self-imposed constraint makes the hiring pipeline incredibly "inelastic" and slow to refill, a reality that exacerbates the staffing shortages detailed in Part 2.

Medically, candidates must pass an exacting examination, which is then requalified annually for their entire career. The requirements are unforgiving:

• Vision: Applicants must demonstrate 20/20 distant and near vision, in each eye separately. The use of bifocal contact lenses is deemed "unacceptable".
• Health: They must be free of glaucoma, cataracts, or chronic eye disease, as well as meet robust standards for cardiovascular, neurological, and psychiatric health.
• Maintenance: Any illness, injury, or incapacitation that occurs between annual exams must be medically cleared before a controller can return to duty.

This annual medical scrutiny creates a uniquely "brittle" career path. A controller's career is in a constant state of jeopardy. Unlike other professions, they can be permanently grounded annually for medical issues (e.g., vision degradation, heart disease) that may be exacerbated by the job's high-stress, sedentary, and shift-work nature. This creates a constant, low-level attrition of experienced controllers, separate from retirements, which further taxes the understaffed system.

Finally, all applicants must pass the Air Traffic Controller Specialists Skills Assessment Battery (ATSA), a pre-employment test battery designed to measure the specific cognitive skills required for the job.

The cumulative effect of these barriers is profound. Less than 10% of all applicants meet all requirements and are accepted into the training program.

The Training Funnel: A Multi-Year Transformation

Passing the initial selection is merely the first step in a multi-year training funnel. Candidates are sent to the FAA Academy in Oklahoma City for intensive classroom instruction and simulation-based training, where they select either the Terminal (Tower) or En Route (Radar) option. This academy has a notoriously high failure rate, with many candidates being weeded out.

Graduation from the academy, however, does not make a controller. Graduates are assigned to an air traffic facility as "developmental controllers". They then begin a supervised, on-the-job apprenticeship that lasts for 1.5 to 3 years. Only after this protracted, high-stakes training period, where they work under the supervision of a certified controller, can they become a "Certified Professional Controller" (CPC).

This multi-year On-the-Job Training (OJT) period is the true bottleneck of the entire ATC system, and it is a bottleneck that is fatally compromised by understaffing. The training process requires a CPC to dedicate time and attention to supervising the developmental controller. In an understaffed facility—where CPCs are already working mandatory 6-day weeks and 10-hour days to manage live traffic—there is little to no capacity left for the intensive, one-on-one training required.

This creates a systemic "death spiral":

• Chronic understaffing (see Part 2) forces CPCs to work exhaustive overtime just to cover operational needs.
• Overworked CPCs have drastically reduced time and cognitive bandwidth for OJT.
• The OJT process for developmental controllers slows down, extending their certification time well beyond the 1.5–3 year window.
• This delay in certifying new CPCs worsens the understaffing, which in turn places even more demands on the existing CPCs, further slowing training.

This lag also explains why "record hiring" numbers, such as the 1,811 new controllers hired by the FAA in Fiscal Year 2024, are a misleading metric of system health. A "new hire" in 2024 is not a functional asset. They are a drain on facility resources for 1.5 to 3 years. That "record hire" is, at best, a potential solution for 2027 or 2028—and only if they pass the high-attrition training, and if the understaffed facility has the capacity to train them in the first place.

The Cognitive War: Managing a Zero-Margin-for-Error Job

The core of the ATC profession is a continuous, high-stakes battle against cognitive overload. The job demands a unique and rare psychological profile, one characterized by high conscientiousness (detail-oriented, strong sense of duty), high agreeableness (essential for teamwork and pilot communication), and, critically, low neuroticism (high emotional stability and resilience to stress).

The daily task is to manage an immense and sustained cognitive load. This involves processing multiple, simultaneous data streams—radar information, rapidly changing weather updates, and constant radio communication with numerous pilots. Controllers must maintain perfect situational awareness and use "judgment to select and take the safest and most effective course of action from among several available choices". This requires exceptional cognitive flexibility and working memory to "hold and manipulate multiple streams of information simultaneously".

This "flow" of cognitive processing is fragile. Research into the cognitive demands of ATC and aviation shows that when an operator's cognitive load increases, or is disrupted by an "off-nominal" event (such as an emergency or a sudden runway incursion), "cognitive processing loads on working memory expand exponentially and rapidly reach a plateau that inhibits safe performance".

This "break point" is the constant, invisible enemy. High cognitive load has been shown to measurably impair a controller's core faculties, including attention, memory, and decision-making abilities. It can even distort their perception of time. The entire job is the active, second-by-second management of one's own cognitive resources to prevent this catastrophic break.

This cognitive fragility is the central vulnerability of the National Airspace System. It is the linchpin that connects all other parts of this report. If the job's core requirement is a stable, rested, focused, and "low-neuroticism" cognitive state, then any external factor that degrades this state is a direct and existential threat to safety.

• Chronic understaffing and 6-day workweeks (Part 2) introduce fatigue.
• DST and shift work (Part 3) introduce circadian disruption and cognitive impairment.
• Government shutdowns (Part 4) introduce financial stress and distraction.

All of these systemic failures attack the one thing the job cannot function without: a clear, rested, and focused mind.

A System in Perma-Crisis: How Chronic Understaffing Pushes the NAS to the Brink

The exceptional baseline difficulty of the ATC job is dangerously amplified by a chronic, systemic crisis of understaffing. This is not a new or temporary problem, but a decade-long structural deficit that has normalized a state of "perma-crisis," forcing the entire system to operate on a foundation of human fatigue.

The Staffing Deficit: A Decade of Doing More with Less

In 2024, the FAA employed 14,264 air traffic controllers. While the agency celebrated "exceeding" its hiring goal of 1,800 by hiring 1,811 new controllers in Fiscal Year 2024, this figure masks a deep and persistent deficit.

A 2025 congressionally mandated report found that from 2013 to 2023, the FAA hired only two-thirds of the controllers it had projected it would need. This hiring deficit, compounded by attrition and the training pipeline breaks from the 2019 shutdown and the COVID-19 pandemic, has left the system critically short.

As of September 2024, the data reveals a system stretched to its limits:

• Widespread Shortages: Over 40% of the FAA's 290 terminal facilities were under the agency's own 85% staffing goal.
• Critical Nodes: Thirty-two of these facilities were staffed at 74.9% capacity or less. Some, like North Dakota's Grand Forks Tower, were at a critical 53.3% capacity. The tower at Hartsfield-Jackson Atlanta International Airport (ATL), the world's busiest, was 17% below full staff.
• The Squeeze: This crisis is defined by a dangerous divergence. From 2013 to 2024, the total number of air traffic controllers decreased by 3.9%, while the annual number of flights rose by 6.5%.

This data is visualized in Table 1, demonstrating the "squeeze" on the workforce.

The FAA's public-facing "hiring goal" is a misleading metric that masks the true staffing deficit. Hitting an insufficient annual goal does not solve the problem; it is a failure of long-term planning. This is compounded by placement issues. While 118 facilities were understaffed in 2024, 85 were over 100% capacity, "partially due to intentional overstaffing of new hires". This indicates that new "developmental" controllers—who are a training burden, as established in Part 1—are being placed in some facilities, while critical, high-traffic hubs remain short on Certified Professional Controllers.

The Fatigue Engine: The Mandatory 6-Day Workweek

The direct, unavoidable consequence of the staffing deficit described in 2.1 is that the FAA must assign mandatory overtime and 6-day workweeks to maintain coverage. The National Air Traffic Controllers Association (NATCA), the controllers' union, has been "sounding the alarm" about this problem for over a decade.

This is not a rare occurrence. In 2022, controllers at 40% of FAA facilities worked 6-day weeks at least once per month. At many of the nation's busiest and most short-staffed facilities, including major radar centers in New York, Chicago, Atlanta, and Dallas, overtime in the form of 6-day weeks and 10-hour days is a common, weekly requirement. NATCA is actively soliciting stories from its members to educate Congress on the "real long-term consequences" of this schedule on their physical and mental health.

This chronic overwork has trapped the FAA in a "Fatigue Catch-22." The root cause (understaffing) prevents the agency from fixing the primary symptom (fatigue).

A clear example of this paradox occurred in April 2024. The FAA, facing intense public scrutiny over fatigue, unilaterally announced new rules regarding rest periods. NATCA publicly warned that applying these new rules to the existing understaffed workforce—without first modeling their impact—would create coverage holes in facility schedules. These holes would then have to be filled by... more mandatory overtime for the remaining controllers. This, the union argued, would increase fatigue and make the new policy "nothing more than window dressing". The system is, in effect, too sick to accept the cure.

The "6-day workweek" is no longer a temporary emergency measure. It has become the de facto operating model for the National Airspace System. This normalization of exhaustive schedules directly degrades the precise cognitive skills—attention, memory, and decision-making—that the job requires, as established in Part 1.

The Tyranny of the Clock: Time, Fatigue, and the Controller

The user's query regarding the difficulty of "time zones and daylight savings" points to a common misconception. For the operation of air traffic control, time zones are not a difficulty; they are a problem that was solved decades ago. The true "difficulty with time" is a far more serious human-factors battle, fought not against geography, but against human biology.

The Global Standard: Why Aviation Uses "Zulu" Time (UTC)

All operational aviation activities, including air traffic control, flight plans, and weather forecasts, mandatorily use Coordinated Universal Time (UTC). This is the primary time standard at 0° longitude (the Greenwich Meridian). In aviation, it is ubiquitously known by its military and phonetic alphabet designation, "Zulu" time (Z).

UTC is used for one express purpose: to avoid all confusion from local time zones and Daylight Saving Time.

A controller in Atlanta, a pilot flying over the North Atlantic, and a controller in Paris are all operating on a single, unambiguous clock. A flight departing Newark (Eastern Time) at 7:00 a.m. local and arriving in Phoenix (Mountain Time) at 9:30 a.m. local appears to take 2.5 hours, a chronological impossibility. In UTC, this flight is simple: a 1200Z departure and a 1630Z arrival, for a flight time of 4.5 hours.

This standardization eliminates operational difficulty. The only cognitive load related to UTC is the minor, persistent "code-switching" a controller must do. Their high-stakes job operates in immutable Zulu time, while their body and personal life operate in variable local time. They must constantly perform the mental conversion. FAA rules state that "local" time may only be used in communications if the speaker explicitly says the word "local" or uses a time zone designator (e.g., "0205M" for Mountain).

This code-switching can lead to confusion in non-operational settings, as one pilot noted in an AOPA article. He arrived four hours early for a "1300" appointment at a flight school, having assumed 1300Z (9 a.m. local), when the school meant 1 p.m. local time. This small-scale confusion highlights the mental "gear-shifting" controllers must perform daily.

The Human Disconnect: Daylight Saving Time (DST) and Cognitive Decline

The real-world difficulty of time management emerges with Daylight Saving Time. Aviation as a system, by operating on UTC, does not observe DST. However, air traffic controllers are humans who live in local time zones that do observe DST. This biannual clock-shift creates two distinct problems:

• Cognitive Impairment: The "spring forward" and "fall back" transitions are known human-factors disruptors. One "big data" study, analyzing performance on a visual search task (a core ATC skill) via a mobile app, revealed a significant drop in performance in the week after a DST transition. Compared to the week before, users were slower, less likely to complete the level, and had more false alarms (errors of commission). While studies looking for a direct link to aviation accidents have found a negligible-to-minor impact—likely due to other safety layers—the data on cognitive impairment is clear. Twice a year, the entire U.S. air traffic system is being managed by a workforce that is, on average, cognitively compromised by sleep disruption.
• The Shifting Conversion: DST adds another layer of cognitive load by changing the conversion factor itself. A controller in New York, who has spent months on Eastern Standard Time (EST) using the mental math "Local = Zulu minus 5," must suddenly, overnight, switch their entire frame of reference to "Local = Zulu minus 4" for Eastern Daylight Time (EDT). This mental "re-gearing" for scheduling, handoffs, and personal life adds a layer of cognitive friction and potential for error at the exact same time their brain is already impaired by the sleep disruption.

The 24/7 Burden: Shift Work and Circadian Dysrhythmia

The single greatest "difficulty with time" for a controller is not time zones; it is time of day. Air traffic control is a 24/7/365 operation. This necessitates rotating shift schedules (morning, evening, night) that force controllers to work against their body's internal clock, or circadian rhythm.

This constant rotation induces "circadian dysrhythmia," a state of de-synchronization between the body's clock and the demands of the job. This condition is a direct cause of chronic fatigue, sleep deficit, reduced well-being, and gastrointestinal disorders.

This is not a theoretical risk. Analysis of incident reports in the Aviation Safety Reporting System (ASRS) database identifies controller-related fatigue, workload, and duty/scheduling factors as recurring themes. Research has shown that performance deficiencies are "highly probable" among controllers working the most disruptive rotation patterns. The FAA acknowledges this risk by allowing for "recuperative rest" (naps) during midnight shifts "to rejuvenate their mental acuity," though this is contingent on traffic volume and staffing.

This is the true, compounding tyranny of the clock for a controller:

• They are on a baseline of circadian disruption from 24/7 shift work.
• Twice a year, DST further disrupts their sleep and degrades their cognitive performance.
• All the while, they must perform the constant, low-level mental "code-switch" between the immutable UTC of their job and the ever-shifting local time of their life.

This combination, layered on top of the chronic staffing crisis (Part 2), creates a workforce perpetually managing a state of fatigue.

Case Study in Collapse: The 2025 Government Shutdown

The 43-day government shutdown of October-November 2025 served as an acute, high-velocity stress test on the chronically fragile ATC system. It pushed the human-factors layer of the NAS past its breaking point, culminating in the unprecedented grounding of the nation's skies by the FAA itself.

"Essential and Expendable": The Psychological Burden of Working Without Pay

As "excepted" or "essential" federal employees, the nation's 14,000+ air traffic controllers were required by law to report to work during the shutdown. They were also not paid for this work.

As the shutdown dragged on, controllers missed one, then two paychecks. This plunged a high-salary, high-stress workforce into a financial crisis, creating "immense stress and fatigue". Controllers reported "debilitating financial worries". The cognitive dissonance was profound: they were deemed "essential" enough to hold the safety of 2.7 million daily passengers in their hands, but not essential enough to pay.

This financial stress was not just a personal problem; it was an immediate and direct threat to aviation safety. As established in Part 1, the ATC job requires a hyper-focused, "low-neuroticism" cognitive state. This state was "distracted" and "overburdened" by the stress of not knowing how to pay their bills. One former pilot noted the danger: "When you have air traffic controllers with high responsibility level... to now to be added with the stress of how can I pay my rent or my mortgage or put food in the table for my family". One controller reported that "Air traffic controllers are texting I don't have enough money to put gas in to come to work".

To make ends meet, controllers were forced to take second jobs. One controller, Jack Criss, wrote publicly that after his 8-hour shift performing a "zero margin for error" job, he would "clock into DoorDash, trying to make ends meet for my daughter and me".

This reality is a fatigue multiplier of catastrophic proportions. The controller is already on a mandatory 6-day week and 10-hour day due to the staffing crisis (Part 2). The shutdown adds the profound psychological stress of financial ruin and the physical exhaustion of a second job. This created an untenable level of human fatigue that the system was not designed to withstand.

The Breaking Point: Mass "Call Outs" and Staffing Collapse

The direct result of this unsustainable pressure was a "surge" in "call outs" (absences and sick leave). Controllers, under immense financial and psychological distress, were "not showing up for work".

The impact on the NAS was immediate and crippling. The FAA reported that "strained staffing levels at multiple facilities" led to "widespread impacts".

• At one point, half of the nation's "Core 30" airports were experiencing controller shortages.
• In the critical New York-area airspace, 80% of facilities were understaffed.
• Facilities like Orlando International Airport (MCO) and Hollywood Burbank Airport (BUR) had their towers temporarily unstaffed, forcing ground stops or forcing pilots to coordinate amongst themselves.

This collapse was not the result of a coordinated strike, which the controllers' union did not condone. Rather, it was a symptom of the system's pre-existing fragility. The NAS was already operating with zero resilience due to the chronic understaffing detailed in Part 2. As reports from the 2019 shutdown also noted, "a slight increase in sick leave... was enough to throw some major East Coast airports into chaos". The 2025 "call outs" were having an "outsized impact... because many FAA facilities were already understaffed". The system had no "slack" or "give."

Grounding the Skies: The FAA's Unprecedented Flight Cuts

By the first week of November 2025, the human-factors failure had become a full-blown operational crisis. Citing "safety concerns" stemming directly from the controller shortage, the FAA took the unprecedented step of ordering airlines to reduce their own flight schedules at 40 of the nation's busiest airports.

The FAA, the agency responsible for the efficiency of the NAS, was forced to shrink the system to "slow the flow of traffic" to a level its depleted and exhausted workforce could safely manage.

The timeline of this collapse, detailed in Table 2, is stark.

In total, this self-inflicted grounding, which lasted 10 days, caused over 11,800 flight cancellations. It provides an undeniable causal chain: a political impasse led to financial and psychological stress on the workforce, which degraded the system's human infrastructure, forcing a system-wide operational failure.

The Long-Term Scars: Why a Shutdown is Never "Over"

The end of the 2025 shutdown and the resumption of normal flight schedules did not mark the end of the crisis. It marked the beginning of a long, multi-year "echo" of damage. A government shutdown is not a "pause" button; it is a structural wound on the NAS. This is evident by examining the long-term impacts of the 35-day shutdown of 2018-2019, a crisis from which the FAA still had not recovered six years later.

The Broken Pipeline: A One-Month Closure, A One-Year Setback

The most significant, invisible damage from a shutdown is the breaking of the training pipeline. During the 2018-2019 shutdown, the FAA was forced to close its training academy in Oklahoma City. All classroom and simulator training for new hires was suspended.

The impact of such a closure is not 1:1. It is exponential. An FAA official, quantifying the damage from the 2019 event, stated:

"If we were to take a shutdown... for 15, 20, 30 days, that's going to set us back at least a year on the progress that we've made".

The "re-start" is a logistical nightmare. It involves recalling instructors, rebuilding student cohorts from applicants who may have taken other jobs, and renegotiating expired contracts for simulators and facilities. This "pause" in the pipeline is still being felt six years later and is a direct contributor to the 2024-2025 staffing crisis (Part 2).

The 43-day shutdown of 2025 has created a new 1-to-1.5-year "hole" in the training pipeline. This "hole" will not be fully felt today. It will arrive in 2028, 2029, and 2030, just as the controllers who would have been hired in 2025 should have been completing their OJT and becoming Certified Professional Controllers. This is a self-inflicted, generational wound that guarantees future staffing shortages.

The Brain Drain: The Accelerated Attrition of Experience

While the broken pipeline stops new talent from entering the system, the "brain drain" accelerates veteran talent leaving it.

The financial and mental strain of working without pay destroys morale and causes "spiking" resignations. But the most alarming statistic is the loss of irreplaceable experience. During the 2025 shutdown, retirements quadrupled, jumping from a daily average of 4 per day to as many as 15-20 per day.

These are not new hires. These are veteran CPCs, the most experienced and skilled controllers in the system, who were eligible for retirement and "decided to walk away" rather than continue to work indefinitely without pay.

This is the second, and more insidious, long-term scar.

• You can (eventually) train a new controller in 3-5 years.
• You can never get back 20 years of experience that "walked away".

This "brain drain" creates a permanent experience deficit in the towers and radar rooms. It leaves the less-experienced CPCs with an even greater share of the workload, and it removes the critical mentors needed to train the next generation of developmental controllers. This permanently increases the systemic risk and "difficulty" for everyone left behind.

Conclusion: The Future of the Tower and the High Cost of Neglect

The findings of this report are conclusive: the difficulty of being a U.S. Air Traffic Controller has been dangerously amplified by systemic neglect.

The job's inherent, high-stakes cognitive demands (Part 1) are being stretched to the breaking point by a chronic, decade-long staffing crisis (Part 2). This crisis has normalized a work-life of constant fatigue, where 6-day weeks are common and the human body is in a constant battle with circadian disruption (Part 3).

This "brittle" system, operating with no resilience, was shattered by the acute political failure of the 2025 government shutdown (Part 4). The shutdown provided definitive, costly proof that the system's "human-factors" layer is its single point of failure. Financial and psychological stress is as tangible a threat to the National Airspace System as an engine failure or a radar outage.

The long-term scars of this neglect are deep and will be felt for years. The broken training pipeline and the accelerated "brain drain" of veteran talent guarantee that the 2025 crisis will echo, ensuring future staffing shortages. The U.S. National Airspace System is now arguably less safe, less stable, and less experienced than it was before. For the controllers who remain—the unseen guardians in the tower—the difficulty of their job has been permanently, and avoidably, increased.