The world's major airlines are bracing for impact amid the coronavirus outbreak, with United, Delta and Virgin drastically slashing their flight schedule, taking other cost-cutting measures, and storing their large aircraft which will be out of use.

The airlines have requested a bailout package from the government, ranging between $45 billion to $65 billion.

The aid, which has been discussed with lawmakers on Capitol Hill and the Trump administration, is requested in the form of loans, tax relief and grants.

It comes as industry group, Airlines for America, has estimated that the nation's seven largest airlines will run out of money completely between June and the end of the year.

In addition to the airline industry, airports are requesting $10 billion in assistance as it forecasts losses of nearly $9 billion as the demand for travel slows.

Many of the airlines' wide-body passenger planes will be put into storage while demand is low. Flight Radar images show several Delta wide-body aircraft making their way to Arizona and Alabama where they will be mothballed.

The aircraft, which include A330, A350, 767 and 777s, will be stored at Marana in Arizona, and Birmingham, Alabama.

Earlier today, United CEO Oscar Munoz and President Scott Kirby sent a letter to the airline's 100,000 employees, which was made public on Sunday, announcing that flight routes will be slashed 50 per cent in April in May.

'We also now expect these deep cuts to extend into the summer travel period,' the memo read.

United also is cutting its corporate officers' salaries by 50 per cent, citing 'the severity of the situation.'

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Flight Radar images show several Delta wide-body aircraft making their way to Arizona and Alabama where they will be mothballed as demand for travel slows

United Airlines will be slashing its flight schedule 50 per cent in April and May amid the coronavirus outbreak

United Airlines CEO Oscar Munoz (right) and President Scott Kirby (not pictured) on Sunday sent a letter to their employees announcing drastic cost-cutting measures

The coronavirus pandemic so far has claimed 70 lives in the US, with 4,061 cases reported

The letter revealed that in the first two weeks of March - usually United's busiest month - there were more than one million fewer customers on board flights than the same period last year. The airline is projecting that revenue for the month will be $1.5billion lower than in March 2019.

'When medical experts say that our health and safety depends on people staying home and practicing social distancing, it's nearly impossible to run a business whose shared purpose is 'Connecting people. Uniting the world,' Munoz and Kirby wrote to their staff.

The airline said it was working night and day to keep as much pay as possible flowing to employees, even if the situation worsens and 'demand temporarily plummets to zero.'

As of Monday morning, there were more than 174,786 cases of the novel coronavirus around the world and 6,705 deaths. In the US, there were 4,061 confirmed cases and 70 fatalities.

Along with slashing flights and executives' salaries, United management on Sunday opened talks with the airline's unions about lowering payroll expense 'in a way that minimizes what we know will be painful for all of us,' according to the letter.

Over the next months, Delta will be slashing its flight schedules 40 per cent, making it largest capacity reduction in the airline's 95-year history

Delta CEO Ed Bastian announced that he will forgo his base salary for the next six months

A separate letter from United's pilots union leadership to it members said that the airline is 'doing all it can to avoid furloughs,' as CNN reported.

United is not alone as it struggles to stay afloat in the face of a plummeting demand amid the global health crisis.

Low-cost airline Norwegian Air Shuttle said Monday it is cancelling 85 per cent of its fights and temporarily laying off 90 per cent of its staff - 7,300 people.

'What our industry is now facing is unprecedented and critical as we are approaching a scenario where most of our airplanes will be temporarily grounded,' Norwegian Air Shuttle chief executive Jacob Schram said in a statement.

'Several governments in Europe have already said that they will do everything they can to ensure that their airlines can continue to fly when society returns to normalcy.'

Shares in the company were down almost 19 per cent on Monday, down 85 per cent from the start of the year.

The UK-based Virgin Atlantic said it would ground 75 per cent of its fleet by March 26 and by up to 85 per cent at points in April, as it cancelled more flights due to coronavirus.

Virgin, which is 51 per cent owned by billionaire Richard Branson's group and 49 per cent owned by Delta Air Lines, also announced it will also ask staff to take eight weeks unpaid leave over the next three months to try to cut costs but avoid layoffs.

These latest moves come just days after Delta CEO Ed Bastian announced that he will forgo his base salary for the next six months, reported 11Alive.

Virgin Atlantic has announced it will also ask staff to take eight weeks unpaid leave over the next three months

According to Securities and Exchange Commission filings, Bastian's 2018 base salary was about $900,000. Most of his $15million annual compensation package comes from stock awards and options.

In a letter to employees made public on Friday, Bastain said that the speed of the passenger demand drop-off is 'unlike anything we've seen – and we've seen a lot in our business.'

Over the next months, Delta will be slashing its flight routes 40 per cent, making it largest capacity reduction in the airline's 95-year history.

JetBlue, which pulled its first-quarter and 2020 earnings forecast, said it was adjusting schedules between March and early May and was considering more flight cancellations.

The carrier was considering voluntary time-off programs for employees, delaying some hiring and increasing the frequency with which it cleans aircraft.

Top US infectious diseases expert Dr. Anthony Fauci on Sunday warned Americans that the coronavirus outbreak could get worse before it gets better, but said he did not expect the United States to restrict domestic travel in the near future.

Fauci, director of the National Institute of Allergy and Infectious Diseases, told ABC News' 'This Week' program he was confident the U.S. government was doing everything needed to contain the outbreak and avert a worst-case scenario.

Low-cost airline Norwegian Air Shuttle said Monday it is cancelling 85 per cent of its fights and temporarily laying off 90 per cent of its staff - 7,300 people

Some of European airline counters at JFK are seen empty on March 13, 2020

United, American Airlines Group and Delta Air Lines - the three largest US airlines - confirmed Friday they are in talks with the Trump Administration about potential assistance amid a dramatic drop-off in air travel demand due to the coronavirus outbreak.

The White House and lawmakers view the situation with increasing alarm, with an administration official saying on Saturday they want Congress to provide assistance to airlines and other industries badly harmed by the travel demand collapse.

So far there has been no talk of a full bailout like that of the auto-industry in 2009.

While no specific proposal is currently being written, a senior House Transportation and Infrastructure Committee aide said it backs tax relief talks but Republicans are 'considering federal loans for the purchase of jet fuel, and possibly other operational expenses.'