Previous Chapter: Appendix C: Federal Aviation Administration Air Traffic Control Facilities and Staffing Levels
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Suggested Citation: "Appendix D: Estimating the Cost of Staffing-Related Flight Delays." National Academies of Sciences, Engineering, and Medicine. 2025. The Air Traffic Controller Workforce Imperative: Staffing Models and Their Implementation to Ensure Safe and Efficient Airspace Operations. Washington, DC: The National Academies Press. doi: 10.17226/29112.

D

Estimating the Cost of Staffing-Related Flight Delays

This appendix draws on Federal Aviation Administration (FAA) data on delays, including those attributed to staffing, to estimate the cost of these staffing-related delays. All data are drawn from FAA’s Operations Network (OPSNET) database. After reviewing trends in delays, an estimate is made of their costs to passengers and airlines.

The estimated cost of delays in 2024 caused by FAA Air Traffic Control (ATC) staffing shortfalls ranges between $135 million and $165 million, although, as noted below, this estimate does not include delay-related costs the committee is unable to account for due to data inadequacies.

FAA DELAY DATA

FAA provides information about delays reported daily through FAA’s OPSNET. A reportable delay is defined as “delays to instrument flight rules (IFR) traffic of 15 minutes or more, which result from the ATC system detaining an aircraft at the gate, short of the runway, on the runway, on a taxiway, or in a holding configuration anywhere en route.” The delays are then classified into five primary causes:

  1. Weather: adverse weather conditions affecting operations.
  2. Volume: delays due to volume when airport is in optimal configuration with no impacting conditions.
  3. Runway: Reductions in capacity due to runway/taxiway closure or configuration changes.
Page 244
Suggested Citation: "Appendix D: Estimating the Cost of Staffing-Related Flight Delays." National Academies of Sciences, Engineering, and Medicine. 2025. The Air Traffic Controller Workforce Imperative: Staffing Models and Their Implementation to Ensure Safe and Efficient Airspace Operations. Washington, DC: The National Academies Press. doi: 10.17226/29112.
  1. Equipment: ATC equipment failure or outage causing reduced capacity.
  2. Other: All impacting conditions not elsewhere classified, such as airshows, VIP restrictions, military operations. Staffing shortfalls were added as subcategory of “Other Delays” beginning in mid-2022.

Table D-1 shows delays by cause for calendar years 2015–2024, as well as averages for 2015–2019 (pre-COVID), 2020–2021 (COVID), 2022–2024 (post-COVID). Reductions in weather-related delays account for most of the decline in total delays. Runway and volume delays have declined slightly, while delays due to equipment have risen in numbers and duration. The number of delays attributed to “Other Factors” (including staffing) has been more variable, including an unprecedented decrease in 2023 relative to 2022 and 2024 (as well as to pre-COVID years). The committee was not able to identify any reporting changes that would explain the 2023 anomaly. Because of this variability, it used the average of the 2022–2024 period. The average duration of Other Delays has increased from 30 minutes in 2015–2019 to 45 minutes in 2022–2024. All the delay metrics in Table D-1 increased dramatically in 2024 compared to a year earlier.

As staffing delays are subsumed within the Other Delays category, we reviewed the longer-term mix of Other Delays, as shown in Table D-2.

Table D-2 shows that from 2015 to 2019 the share of Other Delays (which includes staffing) were relatively stable, averaging about 5.0% of delays and 3.3% of delay minutes. For the overall 2022–2024 period, there is a marked rise in Other Delays to 6.1% of delays and 6.7% of delay-minutes.

DISTRIBUTION OF TOTAL AND OTHER DELAYS JANUARY 2022–DECEMBER 2024

Table D-3 shows that the Other Delays category was concentrated in the Core 30 Airport facilities (Towers, TRACONS, Tower and Approach Control, and Centers) as well as in the 19 facilities defined as “staffing levels 15% below their standard” in Chapter 2. These 19 facilities (1 Level 9, 18 Levels 10–12) represent approximately 22% of operations, but about 40% of Total Delays and about 45% of Other Delays (which include staffing-related delays).

Page 245
Suggested Citation: "Appendix D: Estimating the Cost of Staffing-Related Flight Delays." National Academies of Sciences, Engineering, and Medicine. 2025. The Air Traffic Controller Workforce Imperative: Staffing Models and Their Implementation to Ensure Safe and Efficient Airspace Operations. Washington, DC: The National Academies Press. doi: 10.17226/29112.

TABLE D-1 Distribution of OPSNET Delays by Cause for 2015–2024 and Averages for 2015–2019, 2020–2021, and 2022–2024

Calendar Total Delays Weather Delays Volume Delays Equipment Delays Runway Delays Other Delays
Year Number Average Total Number Average Total Number Average Total Number Average Total Number Average Total Number Average Total
Delays Minutes Minutes Delays Minutes Minutes Delays Minutes Minutes Delays Minutes Minutes Delays Minutes Minutes Delays Minutes Minutes
2015 325,381 44 14,445,740 206,687 53 10,968,179 76,547 26 2,019,472 1,433 35 50,575 22,486 38 857,877 18,228 30 549,637
2016 345,466 46 15,797,028 228,708 54 12,339,604 80,767 27 2,159,161 1,490 47 70,521 19,231 41 792,644 15,270 28 435,098
2017 444,928 49 21,664,341 265,172 58 15,284,684 105,460 28 2,907,923 1,207 47 56,944 43,472 54 2,362,417 29,617 36 1,052,373
2018 443,533 47 20,711,912 298,811 56 16,716,169 94,541 26 2,414,380 1,359 39 53,454 29,344 33 982,349 19,478 28 545,560
2019 456,011 49 22,468,039 311,403 58 18,124,547 95,032 25 2,386,611 2,942 47 139,689 29,287 44 1,290,992 17,347 30 526,200
2020 92,387 39 3,670,767 51,587 46 2,388,021 28,011 30 851,238 727 40 29,665 5,795 22 133,083 6,267 42 268,760
2021 196,386 40 8,021,469 109,334 46 5,042,661 55,386 31 1,754,918 338 30 10,196 18,402 37 692,261 12,926 40 521,433
2022 266,883 43 11,564,449 153,794 49 7,599,414 73,263 31 2,308,815 1,515 47 72,616 14,349 34 491,480 23,962 45 1,092,124
2023 296,844 42 12,601,253 179,958 48 8,728,894 79,382 31 2,473,710 4,025 59 237,520 25,713 33 867,840 7,766 37 293,289
2024 359,694 44 16,065,315 193,056 51 9,861,692 98,323 29 2,924,101 5,820 54 318,122 38,321 43 1,647,930 24,174 54 1,313,470
Total 2015–2024 3,227,513 44 147,010,313 1,998,510 52 107,053,865 786,712 28 22,200,329 20,856 45 1,039,302 246,400 38 10,118,873 175,035 37 6,597,944
20152019 Average 403,064 47 19,017,412 262,156 56 14,686,637 90,469 26 2,377,509 1,686 43 74,237 28,764 42 1,257,256 19,988 30 621,774
20202021 Average 144,387 40 5,846,118 80,461 46 3,715,341 41,699 31 1,303,078 533 35 19,931 12,099 30 412,672 9,597 41 395,097
20222024 Average 307,807 43 13,410,339 175,603 49 8,730,000 83,656 30 2,568,875 3,787 53 209,419 26,128 37 1,002,417 18,634 45 899,628

SOURCE: FAA OPSNET.

Page 246
Suggested Citation: "Appendix D: Estimating the Cost of Staffing-Related Flight Delays." National Academies of Sciences, Engineering, and Medicine. 2025. The Air Traffic Controller Workforce Imperative: Staffing Models and Their Implementation to Ensure Safe and Efficient Airspace Operations. Washington, DC: The National Academies Press. doi: 10.17226/29112.

TABLE D-2 Total Versus Other Delays, January 2010–December 2024

Total Delays Other Delays Percentage of Total
Number Minutes Number Minutes Number Minutes
2015 325,381 14,445,740 18,228 549,637 5.6% 3.8%
2016 345,466 15,797,028 15,270 435,098 4.4% 2.8%
2017 444,928 21,664,341 29,617 1,052,373 6.7% 4.9%
2018 443,533 20,711,912 19,478 545,560 4.4% 2.6%
2019 456,011 22,468,039 17,347 526,200 3.8% 2.3%
2020 92,387 3,670,767 6,267 268,760 6.8% 7.3%
2021 196,386 8,021,469 12,926 521,433 6.6% 6.5%
2022 266,883 11,564,449 23,962 1,092,124 9.0% 9.4%
2023 296,844 12,601,253 7,766 293,289 2.6% 2.3%
2024 359,694 16,065,315 24,174 1,313,470 6.7% 8.2%
2022–2024 923,421 40,231,017 55,902 2,698,883 6.1% 6.7%
Mean 2015–2019 5.0% 3.3%
Standard Deviation 2015–2019 1.1% 1.0%

SOURCE: FAA OPSNET.

Page 247
Suggested Citation: "Appendix D: Estimating the Cost of Staffing-Related Flight Delays." National Academies of Sciences, Engineering, and Medicine. 2025. The Air Traffic Controller Workforce Imperative: Staffing Models and Their Implementation to Ensure Safe and Efficient Airspace Operations. Washington, DC: The National Academies Press. doi: 10.17226/29112.

TABLE D-3 FAA Total and Other Delays Category by Facility Type, January 2022–December 2024

Total Other Other as Percentage of Total
Number Minutes Number Minutes Number Minutes
Total All Facilities 923,421 40,231,017 55,902 2,698,883 6.1% 6.7%
Core 30 Airports, TRACONS, Centers 847,868 37,056,689 51,843 2,505,239 6.1% 6.8%
% of Total 91.8% 92.1% 92.7% 92.8%
19 Facilities Staffed at 85% or Less of Target 372,074 15,753,042 25,622 1,202,656 6.9% 7.6%
% of Total 40.3% 39.2% 45.8% 44.6%

SOURCE: FAA OPSNET.

Page 248
Suggested Citation: "Appendix D: Estimating the Cost of Staffing-Related Flight Delays." National Academies of Sciences, Engineering, and Medicine. 2025. The Air Traffic Controller Workforce Imperative: Staffing Models and Their Implementation to Ensure Safe and Efficient Airspace Operations. Washington, DC: The National Academies Press. doi: 10.17226/29112.

DELAYS BY SECONDARY CAUSE

Beginning in June 2022, FAA added a new secondary subcategory to the “Other Delays” category. This classification occurs when a facility reports delays due to insufficient staffing. The data are reported in terms of the number of flights delayed, as well as the duration of each delay. Thus, to estimate the total delay due to staffing, it is necessary to aggregate all the flights and the associated time they were affected by the staffing delay. The results are shown in Table D-4. The table shows that delays due to staffing shortages have grown rapidly and now represent more than half of Other Delays. In 2024, the 12,711 delays due to staffing represented 622,669 minutes of delay, averaging 49 minutes.

As shown in Table D-5, of the 622,669 minutes of staffing-related aircraft delays, 86% were attributed to just seven facilities.

TABLE D-4 FAA Delays by Secondary Cause, January 2022–December 2024

Other Delays Number Other Delays Minutes Staffing Delays Number Percentage of Total Other Number Staffing Delays Minutes Percentage of Total Other Minutes Average Minutes Staffing Delays
Jan–Dec 2022 23,962 1,092,124 957 4.0% 22,350 2.0% 23
Jan–Dec 2022 15,502 700,416 957 6.2% 22,350 3.2% 23
Jan–Dec 2023 7,766 293,289 2,677 34.5% 90,412 30.8% 34
Jan–Dec 2024 24,174 1,313,470 12,711 52.6% 622,669 47.4% 49

SOURCE: FAA OPSNET.

TABLE D-5 Concentration of Staffing Delays Versus Staffing Levels, 2024

Facility Minutes of Staffing Delays AFN Staffing Fill Rate
EWR 226,370 87%
PHL 183,934 130%
ZNY 37,953 77%
N90 36,744 74%
AUS 18,096 80%
ZJX 16,860 78%
SFO 16,035 92%
Total All Facilities 622,669

SOURCE: FAA OPSNET.

Page 249
Suggested Citation: "Appendix D: Estimating the Cost of Staffing-Related Flight Delays." National Academies of Sciences, Engineering, and Medicine. 2025. The Air Traffic Controller Workforce Imperative: Staffing Models and Their Implementation to Ensure Safe and Efficient Airspace Operations. Washington, DC: The National Academies Press. doi: 10.17226/29112.

Of these facilities, only PHL was overstaffed. This was likely in anticipation of taking over approach control duties for EWR to ease the demand faced by other New York area facilities (ZNY and N90) that were more than 20% below their staffing standards. Transition of approach control duties to PHL was undertaken deliberately for safety reasons and caused numerous delays.

ESTIMATING THE COST OF FAA STAFFING DELAYS

FAA staffing delays data are used in this section to estimate the annual cost of staffing delays. For January–December 2024, there were 622,669 minutes of reported aircraft delays due to staffing.1 As explained below, the estimated cost of delays due to ATC staffing in 2024 ranges between $135 million and $165 million, depending on assumptions. It is important to note that these estimates are only for direct delays and do not include any subsequent propagated delays, such as missed connections or arrival delays.

Estimating Staffing Delay Costs for Airlines

Two sources of information on airline operating costs are used in this section. The Association for American Airlines (A4A) reports a fleet-weighted average variable operating cost per hour of $6,048, equal to $100.80 per minute.2 FAA reports a fully-allocated cost (including lease/capital costs) of $8,916 per hour, equal to $148.60 per minute.3 Both estimates of airline operating costs are used below.

Using variable operating costs only,
Minutes of Aircraft Delay
•622,669
Airline Operating Costs per minute
•$100.80 (from A4A)
Airline delay costs = 662,669 × $100.80 = $62,765,035
Using fully-allocated costs,
Minutes of Aircraft Delay
•622,669

___________________

1 These are reported departure delays and do not indicate whether delays were at the gate or on the airfield in active operations.

2 See https://www.airlines.org/dataset/u-s-passenger-carrier-delay-costs.

3 See https://www.faa.gov/regulations_policies/policy_guidance/benefit_cost/econ-value-section-4-op-costs.pdf.

Page 250
Suggested Citation: "Appendix D: Estimating the Cost of Staffing-Related Flight Delays." National Academies of Sciences, Engineering, and Medicine. 2025. The Air Traffic Controller Workforce Imperative: Staffing Models and Their Implementation to Ensure Safe and Efficient Airspace Operations. Washington, DC: The National Academies Press. doi: 10.17226/29112.

Airline Operating Costs per minute
•$148.60 (from FAA)
Airline delay costs = 662,669 × $148.60 = $92,528,613

Estimating Staffing Delay Costs for Passengers

FAA estimates the weighted (business and leisure) value of air passenger travel as $47.10 in 2016 and recommends adjusting this figure by the Consumer Price Index for all Urban Consumers (CPI-U) for other years.4 Using this adjustment, the estimated value of passenger travel time in 2024 is $62.04 per hour. In addition, A4A reports that the average number of passengers per flight was 106. Passenger-related delay costs due to staffing are estimated as:

Aircraft Delay Minutes
•662,669
Times: Average passengers per flight
× 106
Equals: Total Person-Delay Minutes
70,242,914
Divided by 60
÷ 60
Equals: Person Delay Hours
1,170,715
Times: Value of Travel Time
× $62.04
Equals: Estimated Passenger Delay Costs
$72,631,159

Estimated Total Staffing Delay Costs (January–December 2024)

Estimate (airline variable operating costs) = $62.8 million (mm) + $72.6mm = $135.4mm

Estimate (airline fully-allocated costs) = $92.5mm + $72.6mm = $165.1mm

___________________

4 See https://www.faa.gov/regulations_policies/policy_guidance/benefit_cost/econ-value-section-1-tx-time.pdf.

Page 243
Suggested Citation: "Appendix D: Estimating the Cost of Staffing-Related Flight Delays." National Academies of Sciences, Engineering, and Medicine. 2025. The Air Traffic Controller Workforce Imperative: Staffing Models and Their Implementation to Ensure Safe and Efficient Airspace Operations. Washington, DC: The National Academies Press. doi: 10.17226/29112.
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Suggested Citation: "Appendix D: Estimating the Cost of Staffing-Related Flight Delays." National Academies of Sciences, Engineering, and Medicine. 2025. The Air Traffic Controller Workforce Imperative: Staffing Models and Their Implementation to Ensure Safe and Efficient Airspace Operations. Washington, DC: The National Academies Press. doi: 10.17226/29112.
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Page 245
Suggested Citation: "Appendix D: Estimating the Cost of Staffing-Related Flight Delays." National Academies of Sciences, Engineering, and Medicine. 2025. The Air Traffic Controller Workforce Imperative: Staffing Models and Their Implementation to Ensure Safe and Efficient Airspace Operations. Washington, DC: The National Academies Press. doi: 10.17226/29112.
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Page 246
Suggested Citation: "Appendix D: Estimating the Cost of Staffing-Related Flight Delays." National Academies of Sciences, Engineering, and Medicine. 2025. The Air Traffic Controller Workforce Imperative: Staffing Models and Their Implementation to Ensure Safe and Efficient Airspace Operations. Washington, DC: The National Academies Press. doi: 10.17226/29112.
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Suggested Citation: "Appendix D: Estimating the Cost of Staffing-Related Flight Delays." National Academies of Sciences, Engineering, and Medicine. 2025. The Air Traffic Controller Workforce Imperative: Staffing Models and Their Implementation to Ensure Safe and Efficient Airspace Operations. Washington, DC: The National Academies Press. doi: 10.17226/29112.
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Suggested Citation: "Appendix D: Estimating the Cost of Staffing-Related Flight Delays." National Academies of Sciences, Engineering, and Medicine. 2025. The Air Traffic Controller Workforce Imperative: Staffing Models and Their Implementation to Ensure Safe and Efficient Airspace Operations. Washington, DC: The National Academies Press. doi: 10.17226/29112.
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Suggested Citation: "Appendix D: Estimating the Cost of Staffing-Related Flight Delays." National Academies of Sciences, Engineering, and Medicine. 2025. The Air Traffic Controller Workforce Imperative: Staffing Models and Their Implementation to Ensure Safe and Efficient Airspace Operations. Washington, DC: The National Academies Press. doi: 10.17226/29112.
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Suggested Citation: "Appendix D: Estimating the Cost of Staffing-Related Flight Delays." National Academies of Sciences, Engineering, and Medicine. 2025. The Air Traffic Controller Workforce Imperative: Staffing Models and Their Implementation to Ensure Safe and Efficient Airspace Operations. Washington, DC: The National Academies Press. doi: 10.17226/29112.
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