A220 deice

[digits_]

I'll play the part of the nosy pax here.

Is there anything special on the A220 operated by Air Canada that would prevent it from getting deiced when other planes (also operated by Air Canada) do get deiced and are able to leave?

Talking about the current YYZ 'snow storm'.

[lownslow]

I dunno, maybe barrel icing concerns?

[digits_]

What do you mean by 'barrel icing concerns'?

[fish4life]

Composite vs aluminum construction?

[Pratt X 3]

Maybe it's limited space in CDF and your flight just ain't as special as the other Air Canada flights. Sorry!

[digits_]

Maybe it's limited space in CDF and your flight just ain't as special as the other Air Canada flights. Sorry!

Plane was stationary at the CDF. It was the first one there, waiting. The other planes showed up and got deiced

But yes, definitely possible it wasn't important enough, just curious if there might have been a technical reason.

[lownslow]

What do you mean by 'barrel icing concerns'?

Some engines are more susceptible to intake icing on the ground than others (in places where it seems it can’t be made to go away) but I don’t know where the 220 stands on that spectrum.

[jlfd26]

Where were you going? Maybe ground controller just sent the aircraft there to wait for a wheels up time to an airport that was busy

[Col. Panic]

Where were you going? Maybe ground controller just sent the aircraft there to wait for a wheels up time to an airport that was busy

That was going to be my guess, some sort of flow delay, and not wanting to start a holdover time until closer to wheels up time; although I wouldn't think that they would block a usable deice bay during a snow storm! Did you eventually get deiced? Maybe the crew heard that you were on board and just wanted to see how much they could inconvenience you! Or maybe they just needed some block growth to top up their month.

[digits_]

Where were you going? Maybe ground controller just sent the aircraft there to wait for a wheels up time to an airport that was busy

That was going to be my guess, some sort of flow delay, and not wanting to start a holdover time until closer to wheels up time; although I wouldn't think that they would block a usable deice bay during a snow storm! Did you eventually get deiced? Maybe the crew heard that you were on board and just wanted to see how much they could inconvenience you! Or maybe they just needed some block growth to top up their month.

Destination was CYWG. No flow. We did get deiced.

Cpt said the snow was too heavy to get deiced. Other planes were fine. Reported visibility did not improve or deteriorate between the announcement and the decision to deice an hour later.

[Col. Panic]

Where were you going? Maybe ground controller just sent the aircraft there to wait for a wheels up time to an airport that was busy

That was going to be my guess, some sort of flow delay, and not wanting to start a holdover time until closer to wheels up time; although I wouldn't think that they would block a usable deice bay during a snow storm! Did you eventually get deiced? Maybe the crew heard that you were on board and just wanted to see how much they could inconvenience you! Or maybe they just needed some block growth to top up their month.

Destination was CYWG. No flow. We did get deiced.

Cpt said the snow was too heavy to get deiced. Other planes were fine. Reported visibility did not improve or deteriorate between the announcement and the decision to deice an hour later.

Air Canada has a system at its major airports to accurately measure the precipitation type and intensity, and produce an accurate holdover time based on that information. It is possible that this system (measuring the liquid water equivalent of the precipitation) indicated there was not sufficient holdover time until the precipitation changed, even if there was no change in the METAR reported conditions. Normally this system provides more accurate, and more operationally "helpful" results than the standard HOT tables, but perhaps in this situation, the other operators who were not using the LWE system calculated more favourable HOTs. Or (more likely) they were just aiming for inconvenience.

[digits_]

That was going to be my guess, some sort of flow delay, and not wanting to start a holdover time until closer to wheels up time; although I wouldn't think that they would block a usable deice bay during a snow storm! Did you eventually get deiced? Maybe the crew heard that you were on board and just wanted to see how much they could inconvenience you! Or maybe they just needed some block growth to top up their month.

Destination was CYWG. No flow. We did get deiced.

Cpt said the snow was too heavy to get deiced. Other planes were fine. Reported visibility did not improve or deteriorate between the announcement and the decision to deice an hour later.

Air Canada has a system at its major airports to accurately measure the precipitation type and intensity, and produce an accurate holdover time based on that information. It is possible that this system (measuring the liquid water equivalent of the precipitation) indicated there was not sufficient holdover time until the precipitation changed, even if there was no change in the METAR reported conditions. Normally this system provides more accurate, and more operationally "helpful" results than the standard HOT tables, but perhaps in this situation, the other operators who were not using the LWE system calculated more favourable HOTs. Or (more likely) they were just aiming for inconvenience.

Is this system airplane type specific? Another AC plane did get deiced while we were waiting.

Interesting though, didn't know they had such a system in place.

[skypirate88]

The holdover times are wing material specific. A composite wing seems to have different holdover times then an aluminum wing.

[lownslow]

Cpt said the snow was too heavy to get deiced. Other planes were fine. Reported visibility did not improve or deteriorate between the announcement and the decision to deice an hour later.

I had the same thing happen on a 220 with the same explanation given just yesterday. Best guess is that it’s a holdover time issue with composite wings, IIRC those are much shorter for type 1 de-ice fluid on account of the composite not retaining heat the way aluminum does.

[digits_]

Cpt said the snow was too heavy to get deiced. Other planes were fine. Reported visibility did not improve or deteriorate between the announcement and the decision to deice an hour later.

I had the same thing happen on a 220 with the same explanation given just yesterday. Best guess is that it’s a holdover time issue with composite wings, IIRC those are much shorter for type 1 de-ice fluid on account of the composite not retaining heat the way aluminum does.

Sounds like a great airplane for Canadian winter flying then...

[Curiousflyer]

The discussion revolving around the composite wing is irrelevant in this specific situation. The hold over times for Type 4 is the same for an aluminum and composite wing. There is a slight difference on holdover times for Type 1 fluids on a composite vs aluminum wing, however if it was heavy snow, the Type 4 would need to be applied afterwards.

My best guess is that it had something to do with the difference between the LWE holdover time and using the Metar visibility chart. There is no holdover time for heavy snow using the Metar,. So if the crew was unable to get a holdover time from the LWE sensor, either due to a sensor failure (very common) or a problem with the aircraft receiving the information (less common but still possible) they would not have the information required to safely conduct the flight, regardless of what other planes were doing.

The LWE sensor is a device at the airport that measures how much frozen precipitation is falling. The LWE holdover time is much more accurate than using the traditional visibility method, but is also complex and more prone to failures. Also the LWE sensors give an report based on when it was requested by the pilots. So if it failed for say 10 minutes, some crews wouldn't even be aware of it, as they'd request them at slightly different times.

My next guess would be an anticipated delay for departure that would exceed the hold over time. So if when arriving at the de-ice facility, the crew expected it would take 35 minutes to exit the de-ice facility and take off, but the holdover time was only good for 25 minutes they wouldn't be able to safely take off. Taking a risk on this could pose a serious delay and possibly even cancelling the flight. Think de-ice, taxi to runway, cannot depart because hold over exceeded, taxi back to the gate for fuel, fuel delay, crew hits duty day limit, flight cancelled or massive delay. If the crew figured they could wait in the de-ice facility for 30 minutes, then spray and get out safely, it may have been the more prudent decision.

I'm sure there are dozens of other theories, I've got no inside info, just guessing. Feel free to poke many holes in my theory.