Ice on wings
 

Can sombody tell if if its possible for ice to form on the wings with a ground temperature of 8 degrees C.. I was on an easyjet a320 in alc last weekend delayed by formation of ice.

It certainly is,

If you look up cold soaked wings, you'll get an idea as to how it happens.

Yes. During a long cruise the fuel in the wings can get very cold (-20 plus routinely), and this extra cold fuel cools the skin. Then, if any moisture is encountered in the descent it can cause ice or frost to form on the top and bottom of the wings.

Usually, refuelling with some (relatively) warm fuel is enough to melt it, but not always!

DH

Yes, on the ground ice could form at temperatures well above zero. It requires a particular set of circumstances and would usually be associated with "tankering" fuel. This is means that the company require the aircraft to arrive with as much fuel on board as possible in order to avoid or minimise uplift for the return sector. "Tankering" occurs for various reasons, the most common being fuel price differential but other reasons might include industrial action, lack of fuel bowsers or low fuel stocks. The result is that the aircraft arrives with a relatively large quantity of cold-soaked fuel in the tanks and if temperatures at cruise altitude are low (N. Europe winter) the fuel can be even colder. Now land at an airfield with highish humidity and condensation very quickly forms on the wings that contain a large amount of very cold fuel, result a layer of ice. Now 8 degrees C is a bit on the high side, but add a few knots of wind and the effective temperature could easily be below 5 degrees. I am sure that you have seen how long it can take for frozen ground to thaw, even in sunlight with positive temperature and this is really the problem here. The solutions; wait for it to melt, it will take time but it will happen eventually, de-ice the affected areas (wings) if facilities are available (remember de-icing fluid has to be heated up first) or add some nice warm fuel to raise the temperature of the fuel already in the tanks.

I hope that this answers your question.

YS

Yep, as mentioned above not uncommon. Many aircraft (most?) are allowed to dispatch with frost/ice on the underside of the wings in the fuel tank area, but it has to be removed from the top surface before flight.

Thank you yellow sun.. It was a very calm night. No breeze. Heavy condensation though.. Was after a thirty min turnaround. Never encountered it before at alicante..

It is not unusual to see MD80 series a/c being de-iced in the summer months.

It can happen in the most unlikely places - I see your Alicante and raise you a humid Bermuda and plus 20'ish celsius :eek:.

Once upon a time I walked out from the terminal at BDA to "our" aircraft ( a heavy ) to see the local engineer and station manager stood on the top of the boarding steps glaring at several dozen square metres of ice on the upper surfaces of both wings ...... ( a long story but ultimately it was indeed down to lots of cold soaked fuel).

I'm not sure any of the passengers believed the "reasons for delay" PA and it was just as well it was plus 20 celsius because the nearest deicing rig was probably on the Eastern seaboard.