Prospective flight attendants listen to their instructor during an etiquette training course at Indigo Airlines' Ifly training centre in Gurgaon on the outskirts of New Delhi November 18, 2014. (Photo by Adnan Abidi/Reuters)

Planes land in fog at Heathrow Airport, west London on January 4, 2014, as heavy fog covers a many parts of the south east. (Photo by Steve Parsons/PA Images via Getty Images)

Australian Aboriginal hunter Marcus Gaykamangu of the Yolngu people, carries an Australian native lizard called a goanna over his shoulder as he walks away from a billabong near the “out station” of Yathalamarra, located on the outksirts of the community of Ramingining in East Arnhem Land November 22, 2014. (Photo by David Gray/Reuters)

A house and garden is illuminated ahead of Christmas in Olching near Munich December 11, 2014. The house is decorated with more than 30,000 lights. Every year hundreds of houses across Germany are decorated by their owners with lights ahead of Christmas. (Photo by Michaela Rehle/Reuters)

Female porters carry a holy woman belonging to the Jain community through a street to collect food from local residents living in nearby areas, during early morning in the western Indian city of Ahmedabad December 19, 2014. (Photo by Amit Dave/Reuters)

Children try to walk through a flooded street at Kampung Melayu residential area in Jakarta, December 23, 2014. Torrential rains that have continued in Indonesia in recent days have widened the number of flooded areas that include Jakarta and Bandung, a local newspaper said on Tuesday. (Photo by Reuters/Beawiharta)

Pakistani Christian Maria Akbar, 15, checks herself in the mirror, after having her make up done by hairdresser Razia Rehmat, 39, in preparation for Christmas holiday, at a hair salon, in a slum that hosts Christian families, on the outskirts of Islamabad, Pakistan, Wednesday, December 24, 2014. (Photo by Muhammed Muheisen/AP Photo)

A man carries an injured civilian at a site hit by what activists said was an air strike by forces of Syria's President Bashar al-Assad in the Duma neighbourhood of Damascus December 27, 2014. (Photo by Bassam Khabieh/Reuters)