EXPLAINERNews|AviationWhich airports in the US are cancelling flights?Forty of the country’s busiest airports have been affected by the domestic flight cancellations. Here is the list.

Mass cancellations of flights in the United States are causing havoc for travellers after the government ordered a reduction in the flight schedule due to a lack of air traffic controllers.

The reduced flight schedule, set to begin on Friday, comes as the US continues with its longest-ever government shutdown , which began on October 1, after Congress was unable to agree on a federal funding bill.

Recommended Stories list of 3 itemslist 1 of 3Government shutdown becomes longest in US history as impact felt nationwidelist 2 of 3Longest US government shutdown leaves millions without food aid or paylist 3 of 3The federal shutdown and the Senate filibuster: What could happen now?end of list On Thursday night, the Federal Aviation Administration (FAA) announced a phased-in reduction plan, which sets out that airlines must cut 4 percent of domestic flights from 6am EST (11:00 GMT) on Friday and gradually increase to 10 percent by November 14.

So far, no international flights have been affected by the planned cancellations.

According to an estimate by the aviation analytics firm Cirium, about 1,800 flights are being cancelled – a reduction of 268,000 seats.

Here’s what we know about the cancellations:

Why are flights being cancelled in the US?

Since the October 1 government shutdown, now the longest in history, there has been no sign of the Republicans and Democrats ending their standoff over healthcare funding and agreeing on a new funding bill. Hundreds of thousands of federal workers, including air traffic controllers, have been furloughed or are working unpaid.

While federal workers have received back pay following the end of previous government shutdowns, President Donald Trump has threatened to sack many of them altogether if the Democrats do not agree to sign off on the funding bill.

Advertisement So far, 13,000 air traffic controllers and 50,000 security screeners have been required to work without pay as they are classified as essential workers, so they will not receive payment until the shutdown is lifted.

However, in an attempt to alleviate pressure on the already overworked industry, Transportation Secretary Sean Duffy announced the decision to reduce flights now, before the busy Thanksgiving season at the end of the month.

In a post on X on Thursday night, Duffy said the decision to reduce flights was not about politics but about “assessing the data and alleviating building risk in the system as controllers continue working without pay”.

I don’t have access to money to pay air traffic controllers during this shutdown. Congress has said there is no money. I’d love to pay them, but I can’t.

My message to Democrats is to sit down, figure it out, and not hold the American people hostage- especially when they want to…

Based on reporting by Al Jazeera.