WASHINGTON, Nov 10 (Reuters) - Despite hopes the federal

government shutdown could end this week, air travelers in the

United States are still in for a rough few days of cancellations

and delays nationwide before taking to the skies gets back to

normal.

The Federal Aviation Administration instructed airlines to

cut 4% of daily flights starting last week at 40 major airports

because of air traffic control safety concerns. Reductions in

flights are mandated to reach 6% on Tuesday and then hit 10% by

Friday, November 14 -- and Transportation Secretary Sean Duffy

has warned they could reach 15% to 20% if the shutdown does not

end.

The government might reopen this week, if lawmakers agree to

restore federal funding, but it is unclear when the flight cuts

will be rescinded. On top of the mandated cuts, flyers must also

contend with thousands of delays every day due to rising air

traffic control absences.

The shutdown, the longest in U.S. history, has forced 13,000

air traffic controllers and 50,000 Transportation Security

Administration agents to work without pay.

On Saturday and Sunday alone, more than 1.2 million U.S.

airline passengers were impacted by air-traffic-related delays

and cancellations.

When the shutdown ends, it could take several days or longer

for air traffic to return to normal.

Chris Sununu, the former New Hampshire governor who heads

Airlines for America, told CNN on Monday that there is still "a

tough week ahead. The FAA still has mandated cancellations,

ramping up over the course of the week."

But, he added, "Keep your holiday plans. The system is going

to be up, running viable and resilient by Thanksgiving and

Christmas."

WHAT WILL HAPPEN TO THIS WEEK'S FLIGHT CUTS?

One big question for airlines is when the FAA will lift the

government-required flight cuts. Duffy has said he first wants

to see air traffic control staffing and safety data improve

before removing current targets.

The FAA said last week that 20% to 40% of air traffic

controllers at the 30 largest airports are not showing up on any

given day.

American Airlines ( AAL ) said on Monday that delays and

cancellations due to air traffic control staffing at the weekend

had impacted 250,000 customers.

The FAA has told the airlines that about 24 hours after the

shutdown ends, they can get the controllers their back pay. But

that does not mean absences drop immediately and all controllers

come back to work right away.

WHEN WILL DELAYS START TO GO AWAY?

Airlines canceled more than 2,950 U.S. flights and delayed

more than 11,200 on Sunday in the third day of

government-mandated flight cuts.

The FAA-mandated flight cuts to the top 40 airports

accounted for around 800 flights -- but major airlines ended up

canceling more than twice that figure on Sunday due to fallout

from air traffic control staffing issues.

Delays won't come to an end until air traffic

controllers start getting paid again.

If the shutdown continues, air safety workers would miss

another paycheck this week, leading even more to call in sick so

they can take on second jobs, like driving for Uber or making

deliveries for DoorDash, to make ends meet.

If it lasts two more weeks, it could affect travelers over

Thanksgiving, one of the busiest air travel times of the year.