Aircraft maintenance engineers remove the engine cover from an aircraft as Qantas begins preparing and equipping planes for the return of international flights, in anticipation of Australia easing coronavirus disease (COVID-19) border regulations, at Sydney Airport in Sydney, Australia, October 21, 2021. REUTERS/Loren Elliott

John Walker, head of line maintenance for Qantas, walks under an aircraft as Qantas begins preparing and equipping planes for the return of international flights, in anticipation of Australia easing coronavirus disease (COVID-19) border regulations, at Sydney Airport in Sydney, Australia, October 21, 2021. REUTERS/Loren Elliott

An aircraft appearance crew member cleans an aircraft as Qantas begins preparing and equipping planes for the return of international flights, in anticipation of Australia easing coronavirus disease (COVID-19) border regulations, at Sydney Airport in Sydney, Australia, October 21, 2021. REUTERS/Loren Elliott

An aircraft appearance crew member cleans an aircraft as Qantas begins preparing and equipping planes for the return of international flights, in anticipation of Australia easing coronavirus disease (COVID-19) border regulations, at Sydney Airport in Sydney, Australia, October 21, 2021. REUTERS/Loren Elliott

Aircraft appearance crew members clean an aircraft as Qantas begins preparing and equipping planes for the return of international flights, in anticipation of Australia easing coronavirus disease (COVID-19) border regulations, at Sydney Airport in Sydney, Australia, October 21, 2021. REUTERS/Loren Elliott

Aircraft maintenance engineers remove the engine cover from an aircraft as Qantas begins preparing and equipping planes for the return of international flights, in anticipation of Australia easing coronavirus disease (COVID-19) border regulations, at Sydney Airport in Sydney, Australia, October 21, 2021. REUTERS/Loren Elliott

An aircraft maintenance engineer conducts engine maintenance on an aircraft as Qantas begins preparing and equipping planes for the return of international flights, in anticipation of Australia easing coronavirus disease (COVID-19) border regulations, at Sydney Airport in Sydney, Australia, October 21, 2021. REUTERS/Loren Elliott

Aircraft appearance crew members clean an aircraft as Qantas begins preparing and equipping planes for the return of international flights, in anticipation of Australia easing coronavirus disease (COVID-19) border regulations, at Sydney Airport in Sydney, Australia, October 21, 2021. REUTERS/Loren Elliott

Maintenance personnel walk under an aircraft as Qantas begins preparing and equipping planes for the return of international flights, in anticipation of Australia easing coronavirus disease (COVID-19) border regulations, at Sydney Airport in Sydney, Australia, October 21, 2021. REUTERS/Loren Elliott

Aircraft maintenance engineers conduct engine maintenance on an aircraft as Qantas begins preparing and equipping planes for the return of international flights, in anticipation of Australia easing coronavirus disease (COVID-19) border regulations, at Sydney Airport in Sydney, Australia, October 21, 2021. REUTERS/Loren Elliott

Maintenance personnel walk under an aircraft as Qantas begins preparing and equipping planes for the return of international flights, in anticipation of Australia easing coronavirus disease (COVID-19) border regulations, at Sydney Airport in Sydney, Australia, October 21, 2021. REUTERS/Loren Elliott

An aircraft maintenance personnel member walks past an aircraft as Qantas begins preparing and equipping planes for the return of international flights, in anticipation of Australia easing coronavirus disease (COVID-19) border regulations, at Sydney Airport in Sydney, Australia, October 21, 2021. REUTERS/Loren Elliott

Spectators on a mountain watch a Swiss Air Force F/A-18 Hornet fighter jet performing during a flight demonstration of the Swiss Air Force over the Axalp, in the Bernese Oberland, Switzerland October 20, 2021. Picture taken October 20, 2021. REUTERS/Arnd Wiegmann

A Swiss Air Force F/A-18 Hornet fighter jet performs during a flight demonstration of the Swiss Air Force over the Axalp, in the Bernese Oberland, Switzerland October 20, 2021. Picture taken October 20, 2021. REUTERS/Arnd Wiegmann

Members of the Kommando Spezialkraefte (KSK) special forces are suspended on a rope underneath a helicopter during a flight demonstration of the Swiss Air Force over the Axalp in the Bernese Oberland, Switzerland October 20, 2021. REUTERS/Arnd Wiegmann

Pilots of the Patrouille Suisse perform in their Northrop F-5E Tiger II fighter jets during a flight demonstration of the Swiss Air Force over the Axalp in the Bernese Oberland, Switzerland October 20, 2021. REUTERS/Arnd Wiegmann

A Swiss Air Force helicopter releases flares during a flight demonstration of the Swiss Air Force over the Axalp in the Bernese Oberland, Switzerland October 20, 2021. REUTERS/Arnd Wiegmann

Pilots of the Patrouille Suisse perform in their Northrop F-5E Tiger II fighter jets during a flight demonstration of the Swiss Air Force over the Axalp in the Bernese Oberland, Switzerland October 20, 2021. REUTERS/Arnd Wiegmann

Members of the Kommando Spezialkraefte (KSK) special forces are suspended on a rope underneath a helicopter during a flight demonstration of the Swiss Air Force over the Axalp in the Bernese Oberland, Switzerland October 20, 2021. REUTERS/Arnd Wiegmann

Members of the Kommando Spezialkraefte (KSK) special forces are suspended on a rope underneath a helicopter during a flight demonstration of the Swiss Air Force over the Axalp in the Bernese Oberland, Switzerland October 20, 2021. REUTERS/Arnd Wiegmann

A paratrooper performs during a flight demonstration of the Swiss Air Force over the Axalp in the Bernese Oberland, Switzerland October 20, 2021. REUTERS/Arnd Wiegmann

Pilots of the Patrouille Suisse perform in their Northrop F-5E Tiger II fighter jets during a flight demonstration of the Swiss Air Force over the Axalp in the Bernese Oberland, Switzerland October 20, 2021. REUTERS/Arnd Wiegmann TPX IMAGES OF THE DAY

A Swiss Air Force F/A 18 Hornet fighter jet releases flares during a flight demonstration of the Swiss Air Force over the Axalp in the Bernese Oberland, Switzerland October 20, 2021. REUTERS/Arnd Wiegmann

A vintage Hawker Hunter Mk 58 and four F/A 18 Hornet fighter jets release flares during a flight demonstration of the Swiss Air Force over the Axalp in the Bernese Oberland, Switzerland October 20, 2021. REUTERS/Arnd Wiegmann

Passengers from Amsterdam arrive at Changi Airport under Singapore’s expanded Vaccinated Travel Lane (VTL) quarantine-free travel scheme, as the city-state opens its borders to more countries amidst the coronavirus disease (COVID-19) pandemic, in Singapore October 20, 2021. REUTERS/Edgar Su

Passengers from Amsterdam arrive at Changi Airport under Singapore’s expanded Vaccinated Travel Lane (VTL) quarantine-free travel scheme, as the city-state opens its borders to more countries amidst the coronavirus disease (COVID-19) pandemic, in Singapore October 20, 2021. REUTERS/Edgar Su

Passengers from Amsterdam arrive at Changi Airport under Singapore’s expanded Vaccinated Travel Lane (VTL) quarantine-free travel scheme, as the city-state opens its borders to more countries amidst the coronavirus disease (COVID-19) pandemic, in Singapore October 20, 2021. REUTERS/Edgar Su

Passengers from Amsterdam arrive at Changi Airport under Singapore’s expanded Vaccinated Travel Lane (VTL) quarantine-free travel scheme as the city-state opens its borders to more countries amidst the coronavirus disease (COVID-19) pandemic, in Singapore October 20, 2021. REUTERS/Edgar Su

Passengers from Amsterdam arrive at Changi Airport under Singapore’s expanded Vaccinated Travel Lane (VTL) quarantine-free travel scheme, as the city-state opens its borders to more countries amidst the coronavirus disease (COVID-19) pandemic, in Singapore October 20, 2021. REUTERS/Edgar Su

A view of empty checking desks after flights were cancelled due to an accumulation of volcanic ash, at La Palma Airport, outside Santa Cruz de la Palma, on the Canary Island of La Palma, Spain October 17, 2021. REUTERS/Susana Vera

A Binter airlines staff member walks next to empty checking desks after flights were cancelled due to an accumulation of volcanic ash, at La Palma Airport, outside Santa Cruz de la Palma, on the Canary Island of La Palma, Spain October 17, 2021. REUTERS/Susana Vera

A man looks at an electronic board showing cancelled flights due to an accumulation of volcanic ash, at La Palma Airport, outside Santa Cruz de la Palma, on the Canary Island of La Palma, Spain October 17, 2021. REUTERS/Susana Vera

People line up to board a ferry to the Canary island of La Palma as some flights were suspended to the island due to volcanic ash from the Cumbre Vieja volcano eruption at the port of Los Cristianos in the south of the Canary island of Tenerife, Spain, October 16, 2021. REUTERS/Susana Vera

Volcanic ash covers the steps of a ferry to the Canary island of La Palma as some flights were suspended to the island due to volcanic ash from the Cumbre Vieja volcano eruption at the port of Los Cristianos in the south of the Canary island of Tenerife, Spain, October 16, 2021. REUTERS/Susana Vera

People line up to board a ferry to the Canary island of La Palma as some flights were suspended to the island due to volcanic ash from the Cumbre Vieja volcano eruption at the port of Los Cristianos in the south of the Canary island of Tenerife, Spain, October 16, 2021. REUTERS/Susana Vera

People line up to board a ferry to the Canary island of La Palma as some flights were suspended to the island due to volcanic ash from the Cumbre Vieja volcano eruption at the port of Los Cristianos in the south of the Canary island of Tenerife, Spain, October 16, 2021. REUTERS/Susana Vera

The information screen at Fiumicino airport displays ITA flights as the new airline carrier starts flying in place of bankrupt Alitalia, in Rome, Italy, October 15, 2021. REUTERS/Guglielmo Mangiapane

The information screen displays ITA flights as the new airline carrier starts flying in place of bankrupt Alitalia, in Rome, Italy, October 15, 2021. REUTERS/Guglielmo Mangiapane

The information screen at Fiumicino airport displays ITA flights as the new airline carrier starts flying in place of bankrupt Alitalia, in Rome, Italy, October 15, 2021. REUTERS/Guglielmo Mangiapane

A person is seen in front of an information board displaying ITA flights as the new airline carrier starts flying in place of bankrupt Alitalia, in Rome, Italy, October 15, 2021. REUTERS/Guglielmo Mangiapane

Andrea Gioia, commander of the last Alitalia flight AZ1586, makes a toast to commemorate Alitalia as it is handed over to its downsized successor Italia Trasporto Aereo (ITA), in Fiumicino near Rome, Italy, October 15, 2021. REUTERS/Remo Casilli

Alitalia workers react after the last ever Alitalia flight number AZ1586 from Cagliari landed in Rome Fiumicino airport, as Alitalia is handed over to its downsized successor Italia Trasporto Aereo (ITA), in Fiumicino near Rome, Italy, October 15, 2021. REUTERS/Remo Casilli

Alitalia workers demonstrate after the last ever Alitalia flight number AZ1586 from Cagliari landed in Rome Fiumicino airport, as Alitalia is handed over to its downsized successor Italia Trasporto Aereo (ITA), in Fiumicino near Rome, Italy, October 15, 2021. REUTERS/Remo Casilli

A passenger holds up the ticket of the last ever Alitalia flight number AZ1586 from Cagliari after the plane landed in Rome Fiumicino airport, on the eve of the Italia Trasporto Aereo (ITA) takeover, in Fiumicino near Rome, Italy, October 14, 2021. REUTERS/Remo Casilli

The arrivals board shows the last ever Alitalia flight, number AZ1586 from Cagliari, before its arrival at Rome Fiumicino airport on the eve of the Italia Trasporto Aereo (ITA) takeover, in Fiumicino near Rome, Italy, October 14, 2021. REUTERS/Remo Casilli

The arrivals board shows the last ever Alitalia flight, number AZ1586 from Cagliari, before its arrival at Rome Fiumicino airport on the eve of the Italia Trasporto Aereo (ITA) takeover, in Fiumicino near Rome, Italy, October 14, 2021. REUTERS/Remo Casilli

Roscosmos cosmonaut Alexander Misurkin and space flight participants Yusaku Maezawa and Yozo Hirano attend a news conference ahead of the expedition to the International Space Station, in Star City, Russia October 14, 2021. Japanese entrepreneur Yusaku Maezawa and his production assistant Yozo Hirano, led by Roscosmos cosmonaut Alexander Misurkin, will take part in a mission to the International Space Station (ISS) scheduled for December 8, 2021. REUTERS/Shamil Zhumatov/Pool

Space flight participant Yusaku Maezawa attends a news conference ahead of the expedition to the International Space Station, in Star City, Russia October 14, 2021. Japanese entrepreneur Yusaku Maezawa and his production assistant Yozo Hirano, led by Roscosmos cosmonaut Alexander Misurkin, will take part in a mission to the International Space Station (ISS) scheduled for December 8, 2021. REUTERS/Shamil Zhumatov/Pool

Roscosmos cosmonaut Alexander Misurkin and space flight participants Yusaku Maezawa and Yozo Hirano attend a training session ahead of the expedition to the International Space Station, in Star City, Russia October 14, 2021. Japanese entrepreneur Yusaku Maezawa and his production assistant Yozo Hirano, led by Roscosmos cosmonaut Alexander Misurkin, will take part in a mission to the International Space Station (ISS) scheduled for December 8, 2021. REUTERS/Shamil Zhumatov/Pool

Roscosmos cosmonaut Alexander Misurkin and space flight participants Yusaku Maezawa and Yozo Hirano pose for a picture during a training session ahead of the expedition to the International Space Station, in Star City, Russia October 14, 2021. Japanese entrepreneur Yusaku Maezawa and his production assistant Yozo Hirano, led by Roscosmos cosmonaut Alexander Misurkin, will take part in a mission to the International Space Station (ISS) scheduled for December 8, 2021. REUTERS/Shamil Zhumatov/Pool

Roscosmos cosmonaut Alexander Misurkin and space flight participants Yusaku Maezawa and Yozo Hirano attend a training session ahead of the expedition to the International Space Station, in Star City, Russia October 14, 2021. Japanese entrepreneur Yusaku Maezawa and his production assistant Yozo Hirano, led by Roscosmos cosmonaut Alexander Misurkin, will take part in a mission to the International Space Station (ISS) scheduled for December 8, 2021. REUTERS/Shamil Zhumatov/Pool

Space flight participant Yusaku Maezawa attends a training session ahead of the expedition to the International Space Station, in Star City, Russia October 14, 2021. Japanese entrepreneur Yusaku Maezawa and his production assistant Yozo Hirano, led by Roscosmos cosmonaut Alexander Misurkin, will take part in a mission to the International Space Station (ISS) scheduled for December 8, 2021. REUTERS/Shamil Zhumatov/Pool

Roscosmos cosmonaut Alexander Misurkin and space flight participants Yusaku Maezawa and Yozo Hirano attend a training session ahead of the expedition to the International Space Station, in Star City, Russia October 14, 2021. Japanese entrepreneur Yusaku Maezawa and his production assistant Yozo Hirano, led by Roscosmos cosmonaut Alexander Misurkin, will take part in a mission to the International Space Station (ISS) scheduled for December 8, 2021. REUTERS/Shamil Zhumatov/Pool

Space flight participant Yusaku Maezawa attends a training session ahead of the expedition to the International Space Station, in Star City, Russia October 14, 2021. Japanese entrepreneur Yusaku Maezawa and his production assistant Yozo Hirano, led by Roscosmos cosmonaut Alexander Misurkin, will take part in a mission to the International Space Station (ISS) scheduled for December 8, 2021. REUTERS/Shamil Zhumatov/Pool

Roscosmos cosmonaut Alexander Misurkin and space flight participants Yusaku Maezawa and Yozo Hirano pose for a picture during a training session ahead of the expedition to the International Space Station, in Star City, Russia October 14, 2021. Japanese entrepreneur Yusaku Maezawa and his production assistant Yozo Hirano, led by Roscosmos cosmonaut Alexander Misurkin, will take part in a mission to the International Space Station (ISS) scheduled for December 8, 2021. REUTERS/Shamil Zhumatov/Pool

Space flight participant Yusaku Maezawa attends a training session ahead of the expedition to the International Space Station, in Star City, Russia October 14, 2021. Japanese entrepreneur Yusaku Maezawa and his production assistant Yozo Hirano, led by Roscosmos cosmonaut Alexander Misurkin, will take part in a mission to the International Space Station (ISS) scheduled for December 8, 2021. REUTERS/Shamil Zhumatov/Pool

Space flight participants Yusaku Maezawa and Yozo Hirano attend a training session ahead of the expedition to the International Space Station, in Star City, Russia October 14, 2021. Japanese entrepreneur Yusaku Maezawa and his production assistant Yozo Hirano, led by Roscosmos cosmonaut Alexander Misurkin, will take part in a mission to the International Space Station (ISS) scheduled for December 8, 2021. REUTERS/Shamil Zhumatov/Pool

Space flight participant Yusaku Maezawa attends a training session ahead of the expedition to the International Space Station, in Star City, Russia October 14, 2021. Japanese entrepreneur Yusaku Maezawa and his production assistant Yozo Hirano, led by Roscosmos cosmonaut Alexander Misurkin, will take part in a mission to the International Space Station (ISS) scheduled for December 8, 2021. REUTERS/Shamil Zhumatov/Pool

Space flight participant Yusaku Maezawa attends a training session ahead of the expedition to the International Space Station, in Star City, Russia October 14, 2021. Japanese entrepreneur Yusaku Maezawa and his production assistant Yozo Hirano, led by Roscosmos cosmonaut Alexander Misurkin, will take part in a mission to the International Space Station (ISS) scheduled for December 8, 2021. REUTERS/Shamil Zhumatov/Pool

Space flight participants Yusaku Maezawa and Yozo Hirano attend a training session ahead of the expedition to the International Space Station, in Star City, Russia October 14, 2021. Japanese entrepreneur Yusaku Maezawa and his production assistant Yozo Hirano, led by Roscosmos cosmonaut Alexander Misurkin, will take part in a mission to the International Space Station (ISS) scheduled for December 8, 2021. REUTERS/Shamil Zhumatov/Pool