T/O Flap Retraction and Icing Speeds
Take off flap is 15 degrees.
At "Acceleration Altitude" the "Climb Sequence" is initiated. The nose is lowered with a climb airspeed of 170 Knots set in the ATR 72 (some companies use 180 Knots) and the power management system set to climb (from take off). With the lower nose attitude the aircraft should accelerate ready for flap retraction.
The airspeed for flap retraction depends on whether the aircraft is in "Normal" or "Icing" conditions. In "Normal" conditions on reaching "White Bug" speed the flaps are retracted, but in "Icing" conditions this is delayed until reaching the higher "Red Bug" speed.
"High Bank" is selected at White or Red Bug plus 10 knots depending on whether operating in Normal or Icing conditions respectively.
Per ATR "Icing conditions" are expected when air temperature is less than 7 degrees Celsius and there is visible moisture in the air, etc, etc.
"White" and "Red" bug speeds are determined from the charts dependent on take off weight.
Typically for the ATR 72 at, say, 20 tonnes the speeds are:
White Bug = 134 Knots
Red Bug = 161 Knots
If all the speeds, anti-icing and de-icing procedures are followed then the ATR 42/72 is perfectly safe in cold weather operations.