Everyone has different thoughts over Christmas.

London (Thames, Westminster and “Big Ben”) (Courtesy Richard de Crespigny)

I am currently sitting in cold London contemplating winter.

The shortest day, or Winter solstice occurs in the Northern Hemisphere on about 21 December.   This is the day of the maximum Earth’s cooling rate, though the actual Earth’s temperature lags the “lapse rate” by about one month – so January is the coolest month (+4 degrees Celsius)  and July is the hottest month (+17 degrees).

Will London have have a white Christmas?   Will fog require us to utilise the A380’s wonderfully capable auto-land systems when I return here next time?     Will Alex have a great time as “Tower Boy” at the Cresta?  Will the northern hemisphere have another great ski season?

Long range sectors to cold destinations pose considerable challenges for aviators, even Santa Claus.    Here are some of them:

Surface Fog

London Airport has fog events on average three times per month in October, November, December, January.   Two events per month in February and March.    When fog is present, the A380s can land in fog if we only have just 75 metres of visibility.   When we choose to land in these conditions, it’s not the landing that is the problem, but the taxi to the terminal and then trying to drive on roads where the cars are rendered immobile in the fog.

Surface Snow

London Airport has snow events on average six times per month in January, five in February and four in March and December.   Snow looks pretty, but it plays havoc withe the aerodynamic performance of the wings and control surfaces.  Thousands of litres of de-icing and anti-icing fluid are required to protect an A380 before takeoff in adverse snowing conditions.

Fuel Freezing

Even Santa Clause would be challenged at this time of the year.    USA Jet A fuel starts to freeze at minus 40 degrees Celsius    Jet A1 fuel (that Europe and Australia provides) starts to freeze at -47 degrees Celsius.    Is this a potential problem? – sure.

Cold Fuel

Below are two photos from a flight over Europe at 3 a.m. in the morning when flying at 41,000 feet.   The outside air temperature is minus 70 degrees Celsius (SAT shown at bottom left)  and the temperature of the fuel in the A380’s Outer Fuel tanks has fallen to minus 35 degrees Celsius (shown mid left & right)  – just five degrees warmer than the freezing point of Jet A fuel.  Fuel in the Mid and Inner tanks have cooled to -28 and -14 degrees Celsius respectively.

We have a potential problem, but Airbus have considered and mitigated it.   The second photo shows that the A380’s automatic outer tank transfer function has activated to transfer the cold fuel from the Outer Tanks into the warmer Inner Tanks.   The top image shows the forward fuel transfer galleries transferring this fuel.   Problem averted!   (Though both of our fuel transfer galleries were inoperative during the Qf32 flight).

Had we been in another manufacturer’s large aircraft in this condition, then to prevent the fuel cooling further, we would have been required to either descend into warmer air or speed up to increase the compression (thus temperature) of the air impacting against the air frame.  Both of these actions would have reduced our maximum range.

Cold Outer Tank Fuel (-35 deg C) being transferred from the outer tanks to the inner tanks (Courtesy Richard de Crespigny)

Notice:
1. The “COLD FUEL OUTER TANK TRANSFER” function has been automatically activated.
2. The fans are rotating (N1%) at exactly the same RPMs (to stop “beating” noises) (Courtesy Richard de Crespigny)

Christmas Reflection

Most people will reflect over this period as we see yet another year come to a close.   Did we honour our “New Year Resolutions” and did we do enough to help our family, friends, company and others.

Have we kept up with the new technologies, collaborations and convergences in our new globalised world?

Have we kept up with Gen Y?

The new world is becoming dominated by social media, some of which I believe are here to stay.    Ignore these changes at your peril!      The proof is the power of Twitter, described in QF32 at page 177.    Click here to view a funny perspective of Christmas.

Merry Christmas, Happy and Safe Holidays to you all from Coral, Alex, Sophia and me.