The British romantic comedy Love Actually is saccharine, and occasionally creepy, but it's hard not to be touched by the documentary footage that bookends the movie of families and friends embracing in the arrivals hall of London's Heathrow Airport. Today, those scenes look alien and jarring: A pandemic has turned the world's airports into ghost towns.

Even after the coronavirus abates, air travel will be scarred permanently. No wonder investor Warren Buffett has sold his stocks in US airlines.

How to get passengers off their plane and through passport control, baggage reclaim and arrivals without putting them in proximity with one another is just one of countless travel challenges created by Covid-19.

Assigning the necessary space for people on flights won't be any easier. Years of airline cost cuts and strict counterterrorism checks have made flying a frustrating experience for passengers. Hygiene measures, health checks and social distancing will only make the experience feel more dispiriting, whether you're in economy or business.

Unless accompanied by higher ticket prices, the new health steps could make flying less profitable, whether or not demand returns. That's bad news for the world's airlines, which are now burning through vast amounts of cash.

In some cases, companies' net borrowings will far exceed their revenues by the end of this year.

Besides China, where domestic services have restarted, airlines have pretty much grounded their entire fleets. The few aircraft still in service often take off almost empty.

The silver lining of this near hibernation is that it provides a less pressured environment for testing out new hygiene measures. These will be essential to reassuring passengers and governments that more flights won't lead to a second wave of infections, but they're not likely to make flying any more fun.

The biggest American carriers say customers must wear masks. Armrests, tray tables and seat-belt buckles are being disinfected after every journey, and in-flight magazines have been removed. To minimise physical contact with airline staff and other passengers, we'll scan boarding passes ourselves and we'll be offered less food and drink on board.

It's not yet clear how passengers will be screened for Covid-19 until there's a vaccine. At a minimum, we'll probably have our temperatures checked when we arrive at the airport, but this won't weed out the high proportion of asymptomatic virus cases. Blood tests or so-called "immunity passports" may be required for international travel but even these have limitations.

Passengers who disembark from a high-risk location may still have to enter quarantine, which could deter many from booking a ticket in the first place. Health checks will slow down getting through immigration and you can probably forget arriving only two hours before a flight. This could mean even more passengers waiting inside (or outside) the terminal.

No wonder Heathrow chief executive John Holland-Kaye thinks keeping the required 2m gap at all times will be "physically impossible". A less palatable alternative for Mr Holland-Kaye and his peers, though, is that governments cap the number of departing flights to prevent crowding.

European airlines, chief among them Ryanair, say much the same thing about physical distancing inside aircraft. Some carriers are leaving the middle seat empty but the health benefits are dubious.

Modern planes have air-filtration systems that remove viruses, but these might not protect you if the person in the seat in front or behind has a cough. Leaving seats empty also creates more carbon pollution per passenger carried.

Naturally, airlines worry how they'll make money if they're allowed to sell only two-thirds of their seats.

European carriers typically need to fill about 80 per cent of them to break even. To compensate they'd have to cut costs or raise prices. The latter will be hard unless demand recovers. Quick turnarounds are imperative for budget airlines, so the longer time needed to clean the cabin between flights isn't good news.

Hygiene rules could make it harder to generate so-called ancillary revenues from things like food sales and priority boarding. And Ryanair and its low-cost peers can forget about holding passengers at cramped departure gates that feel like cattle pens, or packing them into just a couple of buses to reach the plane.

It will probably take years for demand to recover fully because millions of potential passengers have lost their jobs. Business travel will be an especially tough sell.

Firms will worry about protecting employee health and video conferencing has proven itself a viable alternative during the lockdowns. Trade shows and conferences won't recover quickly. Hence airlines are already reducing expenses and retiring older aircraft to prepare for lower demand.

British Airways is poised to cut about 30 per cent of its workforce; US and European peers will no doubt do similar once government furlough subsidies expire.

Airports may have to rethink plans for shiny new terminals and extra runways. On the plus side - for the aviation industry, if not the planet - cheaper jet fuel will help everyone. But in Europe, only a privileged few airlines are benefiting from lavish government bailouts, which could distort competition. If weaker airlines collapse, the survivors will face less competition and may eventually be in a position to raise fares.

Consolidation transformed US airline profits and even convinced Mr Buffett to abandon his aversion to investing in the sector - until the coronavirus came along.

Customers whose taxes rescue the airlines, and who didn't always get a ticket refund when they asked for one during the pandemic, may wonder why they're paying more for a worse experience.

BLOOMBERG

• Chris Bryant is a Bloomberg Opinion columnist covering industrial companies. He previously worked for the Financial Times.