The charity has launched an urgent appeal for donations.
The Thames Valley Air Ambulance has worked out that it's facing at least a £1 million drop in cash, after having to cancel the majority of its fundraising events.
And the charity says that predicted shortfall 'could be a significant understatement.'
TVAA provides pre-hospital advanced emergency critical care in Oxfordshire and the surrounding counties, but has also been covering the cost of its doctors and paramedics taking shifts at the John Radcliffe Hospital during the pandemic.
The shortfall represents more than 10% of its annual income and so it's now calling on the public, where they are able to do so, to consider donating, by clicking here.
The charity has in its 21-year history been entirely funded by the public and community it serves and has not received any funding from the government or National Lottery.
Neil Harman, Thames Valley Air Ambulances Director of Fundraising said: "We are truly in an unprecedented situation. Never before in our history have we anticipated such a large loss in fundraising over such a short period.
"We do want to reassure the public, that whatever the response to our appeal, we will continue to provide lifesaving care in the immediate future and be on hand to back-up the NHS in our efforts to tackle the pandemic.
"We are calling on those that can give, to back us at this time and help us secure our service well into the future".
The charity has also been providing a new inter-hospital transfer service for Covid-19 patients, which it's had to fund itself.
In the last financial year, the number of times Thames Valley Air Ambulance were dispatched to patients in need increased by more than 110%.
In total, the charity's teams of paramedics, doctors and pilots were called out to 2,670 patients across our region.