Airlines Say Permanent Daylight Saving Time Would Take Two Years to Absorb

The airline industry says permanent daylight saving time would take up to twenty-four months to absorb, and the House just handed the Senate a bill that would force the change.

A bipartisan supermajority, and a warning issued the same day

On July 14, 2026, the U.S. House of Representatives passed the Sunshine Protection Act by a vote of 308 to 117. House Clerk Roll Call 238 records the tally, with twenty-two Republicans and ninety-five Democrats voting against the measure. The bill, designated H.R. 139 in the 119th Congress, would lock the entire country onto the clock the U.S. currently observes from March through November, the "spring forward" summer time, and abolish the November "fall back" to standard time. Under its terms, individual states would have to affirmatively exempt themselves before the act took effect if they wanted to remain on permanent standard time instead.

Hours after the vote, Airlines for America, the trade group known as A4A that represents the major U.S. passenger and cargo carriers, issued a formal statement. The change, A4A wrote, "would have considerable implications for aviation, including passenger disruption, crew and aircraft positioning, and domestic and international connectivity issues." The group made a second, plainer point in the same statement: "Airlines operate expansive interconnected domestic and global networks that are reliant on stability and predictability."

Then came the number that has anchored every subsequent industry conversation. A4A publicly stated the change could take up to twenty-four months for airlines to fully absorb into their scheduling systems. The trade group did not oppose the underlying policy. It asked Congress for runway.

Why an airline needs two years to change a clock

An airline's schedule is not a wall calendar. It is a stack of interlocking systems that must remain in constant agreement with foreign carriers, foreign airports, and international air traffic control zones. Reservations, crew rostering, aircraft positioning, maintenance windows, and airport slot allocations are all coded against fixed offsets from Coordinated Universal Time. Shift one country's offset relative to the rest of the world and every transoceanic itinerary in that country's timetable has to be re-timed.

The working precedent is the 2007 extension, when Congress added four weeks to the DST window. Analysts at the time compared the software update effort to a mini "Y2K." Updating software to accommodate that extension cost the U.S. economy an estimated 500 million to 1 billion dollars in total IT work. The Air Transport Association, the predecessor group to Airlines for America, calculated that the 2007 two-month extension alone would cost the U.S. airline industry 147 million dollars. U.S. airlines also faced an ongoing 150 million-dollar-per-year cost coordinating with European partners whose DST calendar did not sync with the new American one.

A permanent switch would reopen that second problem on a larger scale. The United States would slip an hour further out of step with Europe, Asia, and Latin America for the winter months, and every one of the thousands of daily transoceanic flight slots would need to be re-timed on the same runway.

A shorter estimate, from someone who studies airline software

Not everyone accepts the twenty-four-month figure. Henry Harteveldt, founder of the aviation-analysis firm Atmosphere Research Group, has said carriers would likely need "six months to a year to adjust," disputing the airline industry's estimate. Harteveldt's argument is that modern reservation and scheduling software is far more flexible than the 2007-era systems, and that most of the code paths involved are already parameterized against configurable time zone tables rather than hard-coded rules. Harteveldt has also noted that airlines already field passenger complaints during the twice-yearly clock changes, because reservations and arrival times briefly show the wrong hour.

The gap between six months and twenty-four months is not a rounding error. It is the entire policy question. If Congress writes a one-year effective date into the final bill, it accepts Harteveldt's read of the software. If it writes a two-year effective date, it accepts A4A's. The Senate now has to pick.

The cost of doing nothing, and the polling that got us here

The case for changing something, anything, is easier to make. William Shughart, senior fellow at the Independent Institute and a professor of public choice at Utah State University, has studied the economic cost of the twice-yearly clock change for decades. Shughart estimated that if every American took just ten minutes on each transition to adjust clocks and watches, the cumulative opportunity cost to the country would reach 1.7 billion dollars. In his own words, describing the productivity cost: "You report to work groggy for a few days and are not as productive."

The polling backs him up. An Associated Press-NORC survey released in December found only about twelve percent of Americans favor keeping the current spring-forward, fall-back system, roughly fifty percent want it changed, and forty percent have no strong opinion. Of those who want a change, roughly fifty-six percent prefer permanent daylight saving time, more evening light, while about forty percent prefer permanent standard time and more morning light. Only two U.S. states, Arizona and Hawaii, currently opt out of the twice-yearly change. Twenty states have already passed legislation to remain on daylight saving time permanently the moment Congress authorizes it.

The disagreement, in other words, is no longer about whether to end the clock change. It is about which clock to end on, and how much time to give the industries that have to rebuild their calendars around the answer.

Trucking, hospitals, and a Senate calendar problem

Airlines are the loudest voice in the room, but they are not the only sector on the hook. Trucking companies, freight railroads, hospital scheduling systems, and payroll and reservation IT platforms would all need re-coding on the same timeline as the carriers. Each of those industries operates its own interlocking dispatch layer, and each has its own version of the A4A ask: give us runway, or watch the errors pile up on the customer side.

Senator Tom Cotton, Republican of Arkansas, blocked a Senate attempt in October 2025 to fast-track the previous version of the bill by unanimous consent. Cotton has argued that permanent DST would push winter sunrise past 9 a.m. in parts of the country, particularly the northern Great Plains and parts of the Northwest. Senate Majority Leader John Thune must now decide whether to schedule a formal Senate vote on H.R. 139. The bill has White House backing; the administration has publicly urged the Senate to pass it, and the President is expected to sign the measure if it clears Congress.

That leaves one question in front of the Senate, and it is not the one most of the coverage is chasing. It is not whether the country wants the change. Twelve percent is a settled number. It is whether Congress writes a two-year runway into the effective date, as Airlines for America is asking, or a shorter one closer to Harteveldt's estimate, and lets the carriers, the freight networks, the hospitals, and the payroll platforms sort the difference out on their own dispatch screens.

Sources

• Airlines for America statement, July 14, 2026
• House Roll Call 238, H.R. 139, 119th Congress
• Atmosphere Research Group commentary, Henry Harteveldt
• Independent Institute, William Shughart research
• AP-NORC Center survey on daylight saving time