When do you consider you are in icing conditions JETS

[RENURPP]

I am looking for information regarding when your company and the aircraft manufacturer determines you are in airframe icing conditions.

Is it at a certain TAT or are they basing it on OAT.

If you could advise whether you are reffering to Boeing or Airbus would be helpful.

thanks

[squidward]

OAT less than +10C... (Airbus)

[Capt Claret]

B717 AFM (section 15 norm ops I think) less that 6 degrees TAT & visible moisture, or less than 3 degrees split between OAT & dew point. :8

[Artisan]

B737

+10 TAT to -40 SAT, visible moisture with a visibility of less than 1 Sm (1600m).

On ground; less than or equal to +10 TAT with visible moisture as above OR; apron, taxiways, manoeuvring areas have significant amounts of water, slush ,snow etc.

[bucket_and_spade]

Ditto. The B757 is as per Artisan's post too.

[RENURPP]

OK next question, do you get airframe icing above those temps?

I regularly see icing on the windscreen at TAT around +20, i assume there is more on the airframe. Icing is visible below OAT of zero, (the freezing level).

The MEL has multiple requirement that reference no flight into known or forecast icing conditions.
I think I maybe missing something here.
We see ice at temps below 0 OAT yet our manual suggests icing is only a problem at temps below 6 degrees TAT in visible moisture. Anyone have any info to fill in the blanks for me?

[Artisan]

Renurpp,

During certification of an aircraft for flight in icing conditions, a temperature range is determined, where the aircraft is at risk. Within this 'at risk' temperature range, the engine/wing anti-ice/de-ice must be used. Outside this range, there is no percieved risk. In some aircraft types, use of wing anti-ice/de-ice above and below the temperature range can actually damage the equipment.

As far as the MEL application goes, I have always applied it thus;
(1) If you CAN stay completely out of cloud then do so,
(2) If you can't stay out of cloud, then you must stay out of the 'at risk' temperature range. This might mean flying lower or delaying the flight until problem is fixed or WX improves.