Takeoff into light freezing rain

BeechBoy

BeechBoy

New Member
Below is an excerpt from the Dornier 328 (jet) AFM (Limitations Section 02-08-00) regarding non-certificated/severe icing conditoins.

"WARNING: Severe icing may result from environmental conditions outside of those for which the airplance is certificated. Flight in freezing rain, freezing drizzle, or mixed icing conditions (supercooled liquid water and ice crystals) may result in ice build-up on protected surfaces exceeding the capability of the ice protection system, or may result in ice forming aft of the protected surfaces. This ice may not be shed using the ice protection systems, and may seriously degrade the performance and controllability of the airplane."

Since freezing rain/freezing drizzle constitute supercooled large drops (SLD) which have been proven to result in severe ice accumulation and ice accumulation aft of the de-ice boots, my interpretation of the above paragraph is that takeoff into freezing rain (even light freezing rain) or freezing drizzle should not be attempted in this type of aircraft (even if the aircraft has had Type 4 anti-icing fluid applied).

The reason I bring up the Type 4 issue is that my Chief Pilot is of the opinion that if the airplane has been de-iced with Type 4 and the holdover time has not been exceeded it is permissible to take off into these conditions. My opinion is that the protection offered by Type 4 is lost as soon as the airplane becomes airborne - yeah, you're safe until you rotate but from that point on you're flying into non-certificated icing conditions.

Does anyone have any opinion on this?

Edit: This is the only official word we have regarding this specific type of precipitation. We have a company manual that gives holdover times, etc, but nothing detailing specifics about freezing rain/drizzle.
 
Do you have a FOM (or GOM) that specifies the types of winter ops authorized in that aircraft?

Without such guidance I have to agree with you. Anti-ice fluid (IV) is a Newtonian fluid that is designed to flow off during the takeoff roll, leaving a clean wing by around 100KIAS. At that point the aircraft's anti-icing system is expected to take over, if needed. If such a system is incapable of handling the anti-ice load then I would say don't fly into it.

Edit: I asked a friend who flew the 328JET and he was under the impression the jet version has bleed air anti-ice and not boots. Is the AFM you reference for both versions or just the jet?
 
BeechBoy said:
Below is an excerpt from the Dornier 328 (jet) AFM (Limitations Section 02-08-00) regarding non-certificated/severe icing conditoins.

"WARNING: Severe icing may result from environmental conditions outside of those for which the airplance is certificated. Flight in freezing rain, freezing drizzle, or mixed icing conditions (supercooled liquid water and ice crystals) may result in ice build-up on protected surfaces exceeding the capability of the ice protection system, or may result in ice forming aft of the protected surfaces. This ice may not be shed using the ice protection systems, and may seriously degrade the performance and controllability of the airplane."

Since freezing rain/freezing drizzle constitute supercooled large drops (SLD) which have been proven to result in severe ice accumulation and ice accumulation aft of the de-ice boots, my interpretation of the above paragraph is that takeoff into freezing rain (even light freezing rain) or freezing drizzle should not be attempted in this type of aircraft (even if the aircraft has had Type 4 anti-icing fluid applied).

The reason I bring up the Type 4 issue is that my Chief Pilot is of the opinion that if the airplane has been de-iced with Type 4 and the holdover time has not been exceeded it is permissible to take off into these conditions. My opinion is that the protection offered by Type 4 is lost as soon as the airplane becomes airborne - yeah, you're safe until you rotate but from that point on you're flying into non-certificated icing conditions.

Does anyone have any opinion on this?

Edit: This is the only official word we have regarding this specific type of precipitation. We have a company manual that gives holdover times, etc, but nothing detailing specifics about freezing rain/drizzle.
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It depends on how thick the icing is, how effective your anti-ice and de-ice actually works, as well as the GOM/FOM. If the FOM/GOM puts a limitation on flight into known icing then you may be limited, however, the 1900 has a verbatim warning issued on page 2-15 of the 1900C AFM. I think the key word is "may" because just below in our book it says:

"During flight, severe icing conditions that exceed those for which the airplane is certificated shall be determined by the following visual cues. If one or more of these visual cues exists, immediately request priority handling from ATC to facilitate a route or an altitude change to exit icing conditions."

It then procedes to list the circumstances. If those circumstances haven't been met, there should be no need for a deviation from the plan, however, if you run into those circumstances then you should request priority handling. I wouldn't worry about it until it starts really building up.
 
Almost every gom/fom//pom that I have heard of allows for -FZRA just not FZRA. It should be in your op specs some where. I guess in a month it really doesn't matter for the DOjet any way:(.
 
Here's the ultimate question you need to ask yourself, "Do you feel lucky punk?"
Haha, JK. :nana2:

The posting I would like to see here would be someone from a manufacturer that has been through the certification process of aircraft de-ice/anti-ice equipment. It is my impression that no aircraft are certified for Severe Icing conditions, hence the definition of the term by the NWS:

"The rate of ice accumulation on an aircraft is such that de-icing/anti-icing equipment fails to reduce or control the hazard. Immediate diversion is necessary. This standard of reporting this type of icing was based on a recommendation set forth by the subcommittee for Aviation Meteorological Services in the Office of the Federal Coordinator for Meteorology in November 1968. The convection has been to designate icing intensity in terms of its operational effect upon reciprocating engine, straight wing transport aircraft as used by commuter operators." It's a tough argument to make that you are operating in accordance within the certification of the aircraft when intentionally flying in any meteorological condition that constitutes severe icing. I also don't buy the argument that it's okay if the freezing precip is only the first 1000' or whatever due to the increased weight hazard from ice adhering to the underside belly. They only certify aircraft to withstand a limited water droplet size striking the deice surfaces. SLD's are more than 1000's bigger than the certification level. Again, just a tough argument to make no matter what company documentation you provide (AFM/GOM/OPS SPECS... ETC). The AFM seems to me to be the first and foremost governing document for the pilot.

Feewwww! I'm glad I got that off my chest. With that said, we all know pilots operate in the stuff. Is it possible to do without running into problems? Apparently, which of course depends on the quality of aircraft you fly. If you choose not to, you have a perfectly good reason for refusing to do it- it is outside the certification of the aircraft.

Fin.:D
 
moxiepilot said:
According to NASA, deicing fluid does not offer protection after Vr as the fluid is supposed to be shed.

http://aircrafticing.grc.nasa.gov/courses.html

It also gets into the reasons for -FRDZ and the associated problems. I'm not disagreeing with you or your chief, just some added knowledge...
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Deice fluid mostly runs off the airplane at taxi speeds. AntiIce (the sticky green stuff, Type II, II, or IV) is designed to shear off the airframe prior to rotation. The reason being that most aircraft with anti ice systems built in, especially for the wing, are effective in flight, but not on the ground.

On the CRJ we can can use engine cowl anti ice one the ground, but we can only turn on the wing anti ice (it's a hot wing, so bleed air warms the inside leading edge) just prior to take off. That way it becomes effective as the anti ice fluid comes off the plane. The hot wing is effective for pretty much everything except SLD icing. Or FOM says something like, "if SLD icing is encountered (evidence of this is ice accumulating on the side windshield) exit the SLD icing conditions".

As far as freezing rain... We can go in -FZRA, but nothing more then that. Same thing with -PL. If it is more then "light" or there is any other precip attached, we are stuck. The thing to keep in mind though is that in the end, even if your winter ops manual says you have hold over times for a certain temp/precip combo, most have some wording at the bottom that states "the airframe MUST be clean for take off". If you have any doubt that with the current precip you're airframe is clean, even with a coat of anti ice on it, you SHOULD be covered if you decide to sit it out for a bit.

FYI, -FZRA and drizzle doesn't always constitute SLD.
 
First off, to answer someone's question about DO-Jet ice protection, it's boots only on the wings and tail.

This is going to be a long post but I think it's worth reading to the end because it shows how management can be 100% convinced that they are right when they are 100% WRONG!!

After cancelling this flight I basically got reamed out by the Chief Pilot. His argument was that the warning in the AFM in no way constituted a limitation against taking off into light freezing rain. The arguments of Skyway management (Director of Safety, Director of Ops, Head of Training, and Chief Pilot) are as follows:

1. Since the warning doesn't specifically mention "light" freezing rain (only freezing rain / freezing drizzle) it may be implied that the AFM was referring to moderate freezing rain & moderate freezing drizzle. (I agree that this is the convention in weather reports but I'm not convinced that the AFM makes this distinction).

2. Since the warning states that freezing rain/freezing drizzle MAY (not WILL) cause control or performance problems it is OK to take off. If you do encounter severe icing then you can use the procedure for exiting severe icing outlined in the AFM. (My opinion: if the AFM says that if you do something you MAY die that's enough for me. I ain't doin' it!).

3. Since we have a holdover time for light freezing rain in our FAA approved company manual it may be implied that it is OK to take off into these conditions. (My opinion: after you takeoff, type 4 protection is gone and you're still in uncertified icing conditions. Also, the FSDO wants to remove the holdover time for flight into light freezing rain because they think it gives a false sense of security that it's OK to fly into these conditions).

4. The NASA icing research on SLD (supercooled large drops) was done on a Twin Otter. We fly a 328 which has a different wing. Therefore, conclusions reached on the Otter cannot be applied to the DO-Jet.


I contacted Dornier 328 Support Services in Germany. Their response: "Takeoff into freezing rain, even light freezing rain, is not permitted". (Skyway doesn't accept this answer: they don't think Support Services has the authority to interpret the warning).

Next I contacted, Bill Rieke, a NASA research pilot who was involved in NASA's icing research for 15+ years. He was also the co-chairman of the first NASA/FAA International Tailplane Icing Conference. In summary, when it comes to aircraft icing this guy is God. His verdict was that even light freezing drizzle can be hazardous to aircraft. Aircraft are certified for flight into "cloud sized droplets" (40-50 microns). These droplets are so small that they will do one of two things if they encounter an aircraft. They will either strike the leading edge of the wing (which is protected) or they will follow the streamlines around the wing without impacting it. Freezing drizzle is 100-150 microns (freezing rain can be 1000 microns or larger). When droplets get larger than 50 microns they are classified as SLD. Droplets this large have enough mass that they will cross the streamlines of the wing and will impact aft of the boots. This is a virtual certainty. When taking off into freezing rain or freezing drizzle (even "light" stuff) you WILL get ice aft of the boots or heated leading edge, it's just a matter of how much. His summary of my actions were "you did the right thing". (Sporty's offers his 40-page book "In-Flight Icing" very inexpensively and it's a very good reference).

I'm sure that there are pilots who have flown in freezing rain and have gotten away with it but I don't care. (I'm not passing judgement. If your AFM says that you're safe for light freezing rain that's one thing but ours does not). I'm 95% sure that I could have taken off and gotten out of the icing before things got out of hand but that's not how I play the game. If I'm safely on the ground I'm not going to take off into potentially hazardous conditions that have a clear warning in the AFM just because the odds are in my favor. Remember the DC-10 that got "microbursted" in Dallas? Do you think that was his first time playing with T-storms? Same thing with the A-340 that ran off the runway in Toronto. My philosophy is that, to the best of my ability, I'm going to do what's right and what's safe - not what others do or have done. Endeth the sermon.
 
It shows your conviction that you took it all the way to the Reike/Van Zant level. However, wouldn't he be required to offer you the most conservative answer or else be open to litigation? The OpSpecs are probably the resource that trumps in this case. I admire how you make decisions and stand by them though, nothing wrong with being safe.
 
Freezing Rain in any form is a no-go for me in the Caravan. Can't really use Type IV on that though. So the rain will freeze on you before you even reach the runway, so it's an easy descision.
 
If you're not comfortable, don't do it. I applaud your firm stance. I'd rather get yelled at than buried.
 
Absolutely unbelievable. Here's how you send the wrong message to your pilots, as a manager or supervisor.

"So, you consulted the AFM and determined that a departure could be unsafe? That's a misinterpretation of the AFM and despite the fact that you "erred" toward caution, I'm suspending you and pending review, you may be fired."

This kind of nonsense strengthens my desire to be involved in the safety department. You can't just tell people to be safe. You have to reinforce safe behavior. This is negative reinforcement, am I right? :confused:
 
ackeight said:
Freezing Rain in any form is a no-go for me in the Caravan. Can't really use Type IV on that though. So the rain will freeze on you before you even reach the runway, so it's an easy descision.
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Not in your op specs? The 208 is approved for type IV.
 
Good for you for standing your ground. Nicely done!

I'm going to double check our company ops for the DoJet tomorrow (I'm guessing they'll be quite similar to yours) to see what they say. I would also have a problem taking off in those conditions.
 
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