True
mmrassi, but why would one ignore such indications? And my point was more that even at seemingly high temps, one can still encounter icing.
Anecdotally I've been told by a colleague, sitting in the rear of the cabin who could hear the change in "air noise" with the selection/deselection of anti ice, that there was still a significant rim of ice on the intake lip when the anti-ice was turned off.
Originally Posted by Douglas/Boeing 717 FCOM
General
Ice protection is provided by the airplane anti-ice systems.
NOTES: Icing can occur on the ground under the following conditions:
• OAT is less than 6°C (42°F), and
• Visible moisture is present (clouds, fog with visibility less than 1 mile, rain, snow, sleet, ice crystals, etc.) or,
• OAT and dewpoint are within 3°C (5°F) of each other or,
• When operating on ramps, taxiways, and/or runways where slush/standing water may impinge and freeze on exterior surfaces.
In flight, icing can occur under the following conditions:
• TAT is less than 6°C (42°F), and • Visible moisture is present, or
• Ice is built up on edges of windshield and other visible portions of the airplane.