De-Icing process

[JP59]

Hello,

I am currently adding an automated de-icing feature to the WidePSX Ground Services module. My question is : how many time does the de-icing process usually takes, for an average amount of ice ? Is it always done on the de-icing zones of an airport or can it also be done at the gate ? Is there a rule to determine the place were the de-icing will take place ? Thanks in advance.

Best regards
Jean-Philippe

[michelvsr]

Hi Jean-Philippe,
Your question is not easy to answer in a few words because the subject is quite complicated.
Depending of the equipment of the airport, the present weather, the type and the thickness of the contamination, the de-icing process can be conducted at the gate or on a special zone of the airport.
For example, to de-ice an aircraft covered with morning frost while the weather is cold but fair, it will take 10 to 15 mn at the gate, before engine start.
For an aircraft covedred with a thick amount of snow or ice, during an winter weather with heavy snow and wind, it will need to proceed in two phases, first de-icing to eliminate the contamination and then, protection with ant-ice liquid. In this case, it will take 20 to 30 mn on a de-icing zone, engines running or not, depending of the airport equipment and regulation.
Michel.

[Hardy Heinlin]

Hello Jean-Philippe,

just in case you want your add-on to detect the current amount of ice on the aircraft: The data can be read from this variable:

Qs429="Icing"; Mode=ECON; Min=11; Max=24;

(More details in the Aerowinx manual, page 474, yellow box "System Analysis").


Regards,

|-|ardy

[JP59]

Hi Michel and Hardy,

@Hardy : I already found this information and I am able to de-ice the aircraft by overwriting the Qs429 to 0;0;0;0;0;0;0 and set the fluid holdover time. Thanks anyway for the information. I have one question : You said that in the Analysis section the amount of ice is indicated in Kgs for Wings L/R and the 4 engines. However, when I see the values in the Qs429 they do not correspond with what is indicated in the Analysis page. What is the unit of the values stored in the Qs429 ? How to convert them in Kgs ?

@Michel : Thanks for the detailed informations. I will see if I can set the de-icing in two phases, depending of the amount of ice detected in the related PSX variable. From my understanding of your explanations, I can think about implementing two scenarios depending of the amount of ice on the aircraft (feel free to comment and/or modify) :

Scenario 1 : Light icing, 10 minutes de-icing at the gate.
Scenario 2 : Strong icing or snow, 10 minutes de-icing at the gate plus 20 minutes at a de-icing bay.

One last question Michel, what is the aircraft status during the de-icing ? You said that in the de-icing bay the engines can remain on. What about the packs, APU (when de-icing at the gate) and other equipments ? Thanks again for the informations.

Kind regards
Jean-Philippe

[michelvsr]

Hi again Jean-Philippe,

For the scenario 2, the 2 phases are made at the same place, special area or gate.
For the de-icing with engines running, there is a special check-list to prepare the operation. Here a part of this Air France checklist

CAUTION:Operate the APU during de-icing only if necessary. If
the APU is running, ingestion of de-icing fluid causes
objectionable fumes and odors to enter the airplane.
Ingestion of snow, slush, ice, or de-icing/anti-icing
fluid can also damage to the APU.

If de-icing / anti-icing is needed:
APU .................................................................As needed F/O
The APU should be shut down unless APU operation is
necessary.
Call “FLAPS UP”. C
Flaps.............................................................................UP F/O
Prevents ice and slush from accumulating in flap cavities during
de-icing.
Thrust levers ...............................................................Idle C
Reduces the possibility of injury to personnel at inlet or exhaust
area.
PACK control selectors..............................................OFF F/O
Reduces the possibility of fumes entering the air conditioning
system.
Wait approximately 10 seconds after pack switches are off before
positioning bleed switches to off to reduce pack wear.
ENGINE BLEED air switches (engines running) OFF F/O
Reduces the possibility of fumes entering the air conditioning
system.
APU bleed air switch (APU running)...................OFF F/O
Reduces the possibility of fumes entering the air conditioning
system.
After de-icing / anti-icing is completed:
APU ............................................................As needed F/O
APU bleed air switch (APU running)....................ON F/O
ENGINE BLEED air switches ..............................ON F/O
Wait approximately one minute after de-icing is completed to turn
pack selectors on to ensure all de-icing fluid has been cleared from
the engines.
PACK control selectors ................................... NORM F/O

Have a nice evening.
Michel.

[JP59]

Thanks Michel these informations are very useful. So if I understand I can implement the de-icing at the gate whatever the scenario is, and it will remain realistic.

Sorry for asking so many questions but I need to fully understand the process in order to implement something realistic in WidePSX. From the checklist I can see that the APU operation is to be avoided during the de-icing process for obvious  reasons. Precisely, during the « in-gate » de-icing, how is the aircraft powered ? Are the engines started exceptionally before the pushback in this situation ?

Best regards,
Jean-Philippe

[Will]

Remember that it's airport-dependent as well. The airport I flew out of didn't deice at the gate; the aircraft would taxi to a deicing stand close to the approach end of the active runway, where all the equipment was assembled.

[Hardy Heinlin]

What is the unit of the values stored in the Qs429 ? How to convert them in Kgs ?

As far as I recall, the display range is such that it doesn't exceed "99". Here's a code snippet with the factors:

Code: [Select]

.append( (int) ( Ice.wingL.iceKgs * 0.0495f ) ).append( ';' )
.append( (int) ( Ice.wingR.iceKgs * 0.0495f ) ).append( ';' )
.append( (int) ( Ice.nacelle1.iceKgs * 1.98f ) ).append( ';' )
.append( (int) ( Ice.nacelle2.iceKgs * 1.98f ) ).append( ';' )
.append( (int) ( Ice.nacelle3.iceKgs * 1.98f ) ).append( ';' )
.append( (int) ( Ice.nacelle4.iceKgs * 1.98f ) ).append( ';' );


Regards,

|-|ardy

[JP59]

From my understanding of the (complex) de-icing process, related with the technical limitations (I can’t build a 20000+ airports database to know which airport has de-icing bays or not), I will implement an automated de-icing service at the gate only, just before pushback, with new ground engineer calls to advise the crew and request the clearance to start the de-icing. The de-icing time will be related with the amount of ice on the airframe (from 10 to 20 minutes), and will lead to a delay from the scheduled out time set in WidePSX. The fluid hold-over time will be set to 45 minutes, starting from the ground engineer call « de-icing completed ».

Thanks Hardy for the factors, I can now calculate the amount of ice from the variable’s informations. Thanks Michel and Will for the explanations, and this very useful checklist.

Best regards
Jean-Philippe

[Will]

I can't code, but I love writing instructions and scripts. What if you check for the state of the engines? If the pilot requests de-icing while the engines are off, then it's done at the gate with the appropriate dialogues. If the engines are on, then it's performed at the de-icing station, wherever that is, with different dialogues. You don't geed to give taxi instructions, because the pilots wouldn't ask for the de-icing process to start until they've arrived at the pad.

[JP59]

Hello Will,

My goal is to make the de-icing process automatically initiated by WidePSX, and not the reverse. This idea came to me from my last flight, where from my warm simulator room, I forgot to de-ice the aircraft. Your scenarios makes sense, but for the above reasons I will remain with my original idea.

Best regards
Jean-Philippe