I still question this "policy" with regards to the level of icing it references. Cessna, did your company specify a level of icing where the AP must be disengaged on approach or was it any ice *period*?
Well, after searching 1500+ pages of "ice" (it's surprising how many times offICEr and servICE show up!), I may have your answer.
In the "Limitations" section of our flight manual, which describes all of the operating parameters (and unfortunately its the chapter that we have to have memorized for obvious reasons), I found absolutely nothing pertaining to the operation of the aircraft/autopilot in icing conditions. Only saw the obvious stuff dealing with when the anti-icing systems must be on. So, with that being said, it initially doesn't look like a hard ticketed item, to use the pun.
When looking through the Operating Policies, here is what I have found. It is worded in such a way to provide the pilot with the choice (I learned in an Aviation Law class that many FARs are also worded this way, to provide loopholes, options, etc). For Cruise
, it says "If there is a significant performance loss in icing conditions, CONSIDER disengaging the autopilot. Leave icing conditions as soon as possible." (emphasis added by me)For Approach/Landing
, autopilot disconnection is never mentioned, but it does say to consider adding up to 10 knots if visible ice is noticed.
Also in the recommendations it says to consider leaving the flaps up as long as possible to avoid additional aircraft icing, and if flaps are deployed in severe icing conditions for an extended time, airframe buffeting may start and is considered normal. If retracting the flaps reduces the buffet, a landing may be made at the discretion of the pilot, applying speed, performance, and runway penalties.
When it says to "consider" disconnecting the autopilot, that goes along with all of the icing training I have received throughout my career, not just with the CRJ. So, there are in fact no real limitations on how much ice we can fly through or when to use the autopilot. It merely gives the pilots the choice of what they want to do. That being said, the CRJ has excellent ice shedding abilities, especially the -700 and -900. There have been a few accidents with the 50 seat series in icing due to the nature of its critical hardwing, but these have only occurred during takeoff at time of rotation, nothing airborne.