Hi guys,

 

as the title says it - I searched the manuals back and forth and couldn't find a hint when to use what switch position. So, what is exactly an icing condition, and when would you select the "on" switch position right away? This bothers me since ever.

Hello Lars,

 

This might help.

 

http://meriweather.com/flightdeck/777/over/antiice.html

 

I'm guessing you should select the AUTO position, that way the aircraft can do it itself.

Icing conditions are normally +10C to -10C with visible moisture (cloud fog or rain).  Anti ice is on in these conditions to prevent the ice accumulation on engine intake nacelle and leading edges of wings. As Mark said, AUTO is normal in the 777.

So there is actually no occasion when you move it deliberately to the "on" position?

Check the QRH, I believe you would use ON if you had a ICE DETECTION message indicating that the ice detector has failed. Think of it as a backup to the automation.

Hi,

 

The FCTM actually gives several hints about how to use the anti-ice (search "anti-ice") and the chapter 3 section 20 of the FCOM v2 (p 3.20.1) explains how the system works and allows to understand as well how to use the switchs.

For engine anti-ice switches for exemple, AUTO will switch the engine anti-ice only in flight. Therefore if you face icing condition on the ground before takeoff or after landing, you should set the switches to ON because if they are set to AUTO, the engine anti-ice will be off as long/soon as the aircraft is on ground.

Thank you very much guys.

 

 

Hi,

 

The FCTM actually gives several hints about how to use the anti-ice (search "anti-ice") and the chapter 3 section 20 of the FCOM v2 (p 3.20.1) explains how the system works and allows to understand as well how to use the switchs.

For engine anti-ice switches for exemple, AUTO will switch the engine anti-ice only in flight. Therefore if you face icing condition on the ground before takeoff or after landing, you should set the switches to ON because if they are set to AUTO, the engine anti-ice will be off as long/soon as the aircraft is on ground.

 

I actually found that section in the FCOM, but I didn't come to the conclusion you made. Good point. So basically the rule is leaving it to "auto" unless you meet icing conditions already on the ground (or after touchdown). And I read that you should taxi with flaps retracted if you don't want to run the risk of having to repeat your de-icing procedure if you taxi long enough.

I had forgotten one reference which will give you all the information that you need:

"Cold weather operations" SP.16.2 in the FCOM v1. It explains thoroughly the de-icing / anti-ice in all phazes of the flight.

I had forgotten one reference which will give you all the information that you need:

"Cold weather operations" SP.16.2 in the FCOM v1. It explains thoroughly the de-icing / anti-ice in all phazes of the flight.

 

I found it and read it. This was exactly what I was looking for, thank you very much.

You are welcome!

Gosh! You guys are so lucky. Only a single switch to worry about. 'Tis true that in the sim there is only one "working" variable. But when you have to design an entire "Airframe and Engine Anti-Ice Panel" which had to be done for the Super VC10 the coding gets a bit complicated especially as on that panel there are 15 switches, 9 magnetic indicators, 4 warning lights, 3 temperature gauges and 4 pressure gauges!!!

Engine anti ice needs to be on on the ground when icing conditions exist. You normally switch it on during the after start/before taxi flow. Then, once the flaps are up during the initial climb, you switch it back to Auto.

In flight, if icing conditions are detected, and the switches are in the AUTO position, Engine anti ice will come on and EAI will be displayed near the N1 gauge.

After landing, you switch Engine anti ice to ON straight away with the after landing flow/when you clean up once you vacate the runway, and leave it on until you shutdown the engines (in icing conditions, of course).

Wing anti ice is never switched to ON on the ground, always stays on AUTO. In flight, the automatic function kicks in if required, and WAI is displayed. Very rare to see WAI in flight.....You can also switch it to ON, but it is not a routine thing to do.

 

I am not sure to what extent the aircraft detects icing conditions in the simulator. I guess it is a very difficult thing to simulate. I did some sort of test the other day... I had engine anti ice on on the ground with 20 degrees C, clear skies, and did not have the EICAS ANTI ICE ON message...

Engine anti ice needs to be on on the ground when icing conditions exist. You normally switch it on during the after start/before taxi flow. Then, once the flaps are up during the initial climb, you switch it back to Auto.

In flight, if icing conditions are detected, and the switches are in the AUTO position, Engine anti ice will come on and EAI will be displayed near the N1 gauge.

After landing, you switch Engine anti ice to ON straight away with the after landing flow/when you clean up once you vacate the runway, and leave it on until you shutdown the engines (in icing conditions, of course).

Wing anti ice is never switched to ON on the ground, always stays on AUTO. In flight, the automatic function kicks in if required, and WAI is displayed. Very rare to see WAI in flight.....You can also switch it to ON, but it is not a routine thing to do.

 

I am not sure to what extent the aircraft detects icing conditions in the simulator. I guess it is a very difficult thing to simulate. I did some sort of test the other day... I had engine anti ice on on the ground with 20 degrees C, clear skies, and did not have the EICAS ANTI ICE ON message...

What is the hot start procedure? Which you would need for a take-off from say somewhere like Kuwait. In the Super VC10 for example the switches are set to normal which dissipates the "excess" temperature during the hot start through the airframe anti-ice ducts to the wings etc. So the EO would check that the MIs (magnetic indicators) on the Ainti-Ice panel were open even though the airframe anti-ice switch would be shut.