Icing up
This is what happens when the droplets of water in suspension in clouds or fog turn to ice on a surface at a temperature lower than 0°C. Any accumulation of ice on the envelope will make the airship heavier and less manoeuvrable. Icing up caused Nobile's airship Italia to crash-land on the sea ice in 1928. Our airship's enveloped will be made of textile that is much smoother, which will make it harder for ice crystals to become attached to it.

Wind
Wind is also a limiting factor. In winds stronger than about 30 kph it is advisable to leave the airship moored to its mast rather than trying to take off. If we run into strong winds once airborne, we can always change altitude to seek more favourable winds.

Difficulties before Spitsbergen
The first difficulties could arise during the flight north from Paris starting in mid-March, because we may still encounter sleet and snowstorms at this time of year between France and the north of Norway. The subsequent stretch, from North Cape to Spitsbergen, a 1,000-km flight across the still frozen Barents Sea, will have to be done in good weather and with a favourable wind because the flight is close to the maximum range of the airship.

Flights over the ice pack
In April, the winds over the Arctic Ocean are light and the cold, dense air over the ice pack will give us extra lift and flight stability.

Assistance during flight
Météo France, which is an invaluable partner for the expedition, will be sending weather forecasts and providing navigational assistance.