Story in brief

• A Cathay Cargo freighter captain explains the challenges of winter flying
• Anchorage ground teams work through snow, ice and sub-zero temperatures
• Aircraft de-icing is essential for safe winter departures
• Severe weather can affect turnarounds, taxiing and flight schedules
• Safety remains the priority when conditions deteriorate

Story in full

Autumn marks the start of winter across much of the Northern Hemisphere. Freighters departing Hong Kong for the Americas may leave in 30°C heat but arrive at Ted Stevens Anchorage International Airport in sub-zero temperatures.

“We usually get our first snow around Halloween,” explains Aaron Freeman, Cargo Services Manager at Cathay Cargo’s busy Alaskan outpost. For Freeman and Line Operations Manager Captain Hayley Hunter, who flies on Cathay Cargo’s Boeing 747 freighter fleet, operating in winter means careful planning. Low temperatures, fog, wind and snow create challenges for people, aircraft and equipment, increasing the risk of delay, injury and damage.

Potential winter impacts

Bad winter weather can lead to congestion at airports. Air traffic control may reduce arrivals and departures to increase safety margins, while ice, slush and snow slow vehicles on the ramp and aircraft on taxiways. Departing aircraft may need de-icing, adding time to turnarounds.

As operations slow, disruption can spread. Parking bays remain occupied longer, incoming aircraft, may divert and delayed departures can push crews towards flight-time limits. Whatever the situation, safety always comes first.

The big freeze

Extreme cold is not only unpleasant, it can be hazardous. Winter temperatures in Anchorage drop to -34°C or lower, making warm clothing essential. For Freeman and his team, getting out of their vehicle and on to the aircraft as quickly as possible is paramount.

Arriving flight crew are picked up in a transfer vehicle at the foot of the aircraft steps, so it is just a brief chill, more so for those pilots who in a moment of sub-tropical forgetfulness omit to pack their Cathay Cargo puffa jackets. But a departing pilot carrying out the pre-flight inspection is really exposed to a challenging environment.

Both Freeman and Captain Hunter also recommend “cleats”, studded soles worn when the tarmac is slippery with ice, snow and de-icing fluid. Freeman adds that they should be removed before boarding to avoid slipping on, or damaging, the freighter’s main-deck floor.

White out

Snow is one of the big disruptors of airport operations. Runways and taxiways must be ploughed so lights and airfield markings remain visible.

It’s not all bad news, though. “It’s actually a little bit warmer when it’s snowing,” says Freeman. “It has to warm up to around -1°C to produce the condensation in the air.”

Getting to work is slower, and although Freeman harbours ideas of living in a wilderness log cabin – “it’s a dream”– it means allowing more time for journeys to work from the city. On the ramp, meanwhile, vehicle speeds are reduced for safety. “You need to have your head on a swivel to have that 360° situational awareness,” says Freeman. This is especially the case in low visibility. “Basically, in snow everything goes a bit slower.”

On the flight deck, taxiing can be challenging too. The Boeing 747 also uses its main landing gear to assist steering along with its nose gear. “We can also use a little bit of differential thrust to help us turn corners, and a little bit of differential braking,” says Captain Hunter.

Snow, slush and ice on the runway can affect take-off performance and braking distances on landing. On board the 747, crews use the Boeing OPT (Onboard Performance Tool), entering runway conditions, wind and contaminant depth to calculate take-off performance. Crews may also increase thrust if there is a crosswind or wind-shear risk “so that we’ve more oomph to power through that lower altitude zone,” says Captain Hunter.

De-icing and anti-icing

Another time-consuming process in wintry conditions is de-icing, which removes snow or ice from an aircraft’s wings and control surfaces. Even a millimetre of ice on a wing can disrupt the flow of air over the wing to stop it having enough lift for take off. On arrival, the crew inspect the wing and, if required, the Engineering team calls out the de-icing contractor.

The process is often carried out in two stages. Heated de-icing fluid removes ice and snow before a thicker anti-icing solution is applied to prevent further accumulation. It then dislodges as the aircraft accelerates on the runway, but the protection is time-limited and may expire quicker during active snowfall. If delays are too long, the entire process has to start again.

Captain Hunter remembers boarding an aircraft in Anchorage and checking the wings were clear despite snow on the ground. “Shortly after, a landing plane used full reverse thrust just behind us and threw up so much snow that we ended up having to de-ice anyway,” she says.

Divert when all else fails

Severe congestion on the ground in Anchorage can mean that incoming aircraft may need to divert. In winter, the first diversion airport is Fairbanks, 260 miles north. “Eight hours by car in winter,” says Freeman. Or a 45-minute flight if one is available.

Fairbanks is sheltered by surrounding hills and winter temperatures fluctuate between -40°C and -50°C. “The benefit of that is that it’s so cold that the snow actually doesn’t stick to the wing, so it’s pretty likely that you wouldn’t need to do de-icing and anti-icing,” says Captain Hunter.

The downside is that refuelling takes longer. “The fuel truck has to go back into the hangar every 20 minutes to warm up because it gets too cold.”

Such are the perils of an Alaskan winter. “We’re a resilient bunch,” says Freeman. “We’re not afraid to get out there and do what needs to get done because at the end of the day we’re just trying to keep the airplane moving.”