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iskyfly
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« Reply #45 on: February 24, 2009, 07:43:30 AM »

Regarding icing and autopilot;
http://www.airdisaster.info/forums/viewtopic.php?f=6&t=2054&st=0&sk=t&sd=a&start=50#p26750

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Autopilot use in icing is not addressed for us in any of our manuals. I believe it was a recommendation that came from the Roselawn accident but was intended for smaller aicraft more susceptible to tail icing/stall. To be honest, tail stall is not even stressed on the big jets and I don't believe I've ever had any training on it. Boeing is apparently unconcerned enough about it that none of the Boeing products that you are familiar with (727/737/757/777) even have tail deicing. They are only equipped with wing anti-ice systems. My MD80 does have tail anti-ice as part of the airframe anti-ice system. I'm not sure if Airbus heats the tail or not. The only thing in our SOP that even touches on the possibility of tail icing/stall is a recommendation that when airframe anti-ice is required down to touchdown, you should select a tail cycle approximately 1 minute prior to selelction of land flaps (the anti ice cycle normally runs 15 mins on the wings followed by 2.5 mins on the tail. You have the ability to manually select a tail cycle and that is the recommendation prior to flap movement....this is only in our MD80 manuals as none of the other planes even have tail heat).

It sounds like Colgan's manuals 'recommended' hand flying in icing conditions. I can understand this as the autopilot will mask any strange control deflections or trim changes that you might otherwise feel when hand flying (the A/P will mask those changes and hold the desired attitude right up until it can't take it anymore and then will disconnect allowing those trim/control forces to do nasty things to the plane). However, it is still just a recommendation and the Captain could have felt that in IMC condtitions at night in adverse weather with a fairly new F/O (etc.) that it was better to keep the A/P on. No doubt that decision will be scrutinized. Their SOP requires handflying with severe icing and nobody is suggesting that severe icing conditions were present. The NTSB briefs keep mentioning 'significant icing', but inflight icing is rare enough that whenever you see a good amount cover the windshild bolts or the windscreen, pilots will always comment and say "wow, look at the ice building up'. That will go on the CVR, but taken out of context, it doesn't mean severe icing. You're not allowed to remain in severe icing....you are supposed to change altitudes/exit severe icing. You certainly wouldn't continue an approach if you felt you were in severe icing.
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cessna157
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« Reply #46 on: February 24, 2009, 08:17:41 AM »

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.
« Last Edit: February 24, 2009, 08:21:01 AM by cessna157 » Logged

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« Reply #47 on: February 24, 2009, 09:56:49 AM »

Cessna, thank you for taking the time to look into the operations policy under which you flew (hint:  search for " ice " should limit the results to just the relevant sentences.  Smiley ).  Iskyfly - thank you also for reposting that quote.

The reason I am questioning this black-or-white finality of the icing policy is exactly what the bolded point in iskyfly's repost stated.   The risks of light-to-moderate icing to an aircraft certified for flight into known ice are indeed much lower than that of other hazards related to night, IMC flight.   Therefore I do not believe there was an operational prohibition of AP use in known light to moderate icing.  

Keep in mind that all other aircraft that night, including a similar model some 23 minutes behind the accident aircraft, reported only to a level of moderate icing on approach into Buffalo.  More importantly, the NTSB has not officially determined the level of icing that night, despite the publicly released comments from the accident flight deck indicating "significant icing."  As was stated elsewhere, caution should be exercised in taking this comment out of context since "significant icing" is not an official, defined level of ice.  For example, the pilots could have been commenting on the ice build-up on the windshield wiper, a part nonessential to the aerodynamics of that aircraft.

Placing the FAA-worded but controversial definition of known ice aside for a moment, consider that just about every cloudy day in the Northeast US from October to March (and there are a lot - too many, actually, and we are all sun-deprived) has a light-to-moderate icing potential.  Had there been such a prohibition of AP use in light-to-moderate ice, this would suggest that every air transport flight over the Northeast skies would be hand-flying approaches, most notably at night, the majority of the time.  Are we really to believe that every air transport aircraft is hand-flying approaches the majority of the time during the six months that make up icing season in the Northeast US?   Absolutely not.

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joeyb747
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« Reply #48 on: February 24, 2009, 06:24:27 PM »

Ok-I have some new information. After consulting a couple of different people, I have this information for you all.

First of all, I was misinformed, and shared incorrect info, and for that i apologize.

The correct info is this: There is no such "requirement" on not using autopilot on approach in icing conditions on any type of aircraft.

However, there are "recommendations". All are type-specific, and vary by model. These "recommendations" are aimed at turboprop aircraft that have deicing boots. Aircraft that use heated leading edge do not have any such "recommendations".

Mesaba has a recommendation on its Saab 340 fleet that the pilot hand-fly the airplane on approach in moderate and higher icing conditions. This is per a NWA Captain. I am not familiar with Mesabas' policies/recommendations or whatever you would like to call them.

American Eagle has a similar recommendation on its ATR fleet, its Jetstream 31 fleet, and its Saab 340 fleet.

The -8, or Q400, has leading edge boots. I'm guessing the recommendation follows those same lines.

I've been told these recommendations came about after the American Eagle ATR crash in Roselawn, IN.
 
But of course, these are just recommendations. It's pilots discretion when to use autopilot or not.

I hope this will help clear up some things. And again, I apologize for the wrong information.     grin
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napper505
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75 th anniversary


« Reply #49 on: February 25, 2009, 09:43:30 PM »

Hey

Was listening to Kbuf tonight

(mesaba?)  was shown as DhD 400 Colgan was redirected to London, contact Toronto Center etc..   between 9:00 pm and 9:30 pm local time

Current weather mixed snow and now mixed freezing rain 30 miles West of YYZ.

Quote from pilot "where do you want us to go?"   huh

There is a front moving thru .  Now listening to both YYZ and kbuf whenever I can


Napper505



« Last Edit: February 25, 2009, 09:55:04 PM by napper505 » Logged

tuned to cyyz
joeyb747
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« Reply #50 on: February 27, 2009, 07:44:42 PM »

napper505:
You posted "(mesaba?)" in your last post. Im not sure if that was a question about who Mesaba is, but if it was, here is some info for you:

Mesaba is a regional carrier for Northwest under the Northwest Airlink banner. They operate CRJs and Saab 340s. Up until 2006 they opeated the Avro RJ85. (I liked that airplane, very unique looking, nice flying too!) Mesaba was founded in 1944 with one Piper Cub! They hub out of KMSP and KDTW. I beleive they serve KBUF from KDTW with the Saab 340. Not for sure on that...


Fleet:

As with all Northwest Airlink partners, the aircraft Mesaba operates are owned by Northwest Airlines. The Mesaba Airlines fleet consists of the following aircraft as of September 2008:

Aircraft Total Passengers
(First/Economy) Routes Notes

Bombardier CRJ-200LR 17
 50 Northwest Airlink 15 transferred from Pinnacle Airlines

Bombardier CRJ-900 36
(36 options)
(7 from other Delta Connection carriers) 76 (12/64) Northwest Airlink

Delta Connection First Operator of the CRJ900 Next Gen

Saab 340B+ 49 (34 Northwest Airlink) 


Retired

Aircraft                                    Year Retired                   Replacement                     Notes

Avro RJ-85                                   2006                      Bombardier CRJ-900      Transferred to Cityjet (Dublin, Ireland)

Fairchild Swearingen Metroliner  1997                             Saab 340 

De Havilland Canada Dash 8      1998                             Saab 340 

Fokker F27                                    ?                                   Dash 8 

Beechcraft Model 99  Metroliner    ?                                       ?

Saab 340A                                2006                                  None 

« Last Edit: February 27, 2009, 07:49:02 PM by joeyb747 » Logged

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napper505
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75 th anniversary


« Reply #51 on: February 27, 2009, 09:25:55 PM »

Hey!!

Thanx for the info on Mesaba. I know about them but I didn't know what the were flying..

My bad!! I got CJC1134 and Mesaba 1134 mixed up on the Flight aware page. embarassed

archive was on feb 26.2009  0200z.mp3     at  around 20.20 minute remaining.

"Where do you want us to go?"

Napper505

I meant to add this link

read from page 30 on.   q400  pilots comments

http://www.pprune.org/rumours-news/362055-continental-turboprop-crash-inbound-buffalo-29.html


« Last Edit: February 28, 2009, 04:16:12 PM by napper505 » Logged

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joeyb747
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« Reply #52 on: March 01, 2009, 08:46:40 PM »

Interesting stuff. Thanks napper505!  grin
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kea001
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« Reply #53 on: March 26, 2009, 11:15:27 AM »

Icing Didn’t Affect Plane in Buffalo Crash, NTSB Says
By John Hughes

March 25 (Bloomberg)

“The circumstances of the crash have raised several issues that go well beyond the widely discussed matter of airframe icing,” NTSB Acting Chairman Mark Rosenker said in the statement. He scheduled a three-day hearing for May 12-14 in Washington.

Also of interest:

"Investigators have found no connection between the accident and a ground obstruction that may affect equipment guiding planes to the Buffalo airport, the NTSB said. Southwest Airlines Co. warned pilots about the obstruction in an advisory issued 13 days before the crash."

more at bloomberg.com
http://www.bloomberg.com/apps/news?pid=20601103&sid=aZKSjzvjBPSQ&refer=us

NTSB Advisory
UPDATE ON NTSB INVESTIGATION INTO CRASH OF COLGAN AIR DASH-8 NEAR BUFFALO, NEW YORK; PUBLIC HEARING SCHEDULED
http://ntsb.gov/Pressrel/2009/090325.html
« Last Edit: March 26, 2009, 11:40:30 AM by kea001 » Logged
SJ30
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« Reply #54 on: March 26, 2009, 02:25:01 PM »

Ok, wait a minute!  You guys are freaking me out here!

Are you guys telling me that when I start flying something that has an auto-pilot coupled to an FMS, that my aircraft will be subjected to control input influences that reside outside of my physical sphere of influence?  Is this what the whole "CAT" system is all about [CAT I, CAT II and CAT II]?

The SJ30-2 has the Primus Epic CDS avionics package with the 615 integrated avionics computer bringing together a flight director, auto pilot and a flight management system.  This is the aircraft that I will be logging anywhere from 260 to 520 hours per year as PIC.  Are you guys telling me that some ILS equipment on the ground at some airport, or the geographical elements of the approach to a specific runway at said airport, could be causal for my aircraft doing something that I did not ask it to do while flying a precision approach? !!!!

Because, if that's what you guys are discussing here in this thread, you have OFFICIALLY scared the snot out of me, completely - 100% snot'less.   shocked

What the........are you guys talking about here?  Please tell me that "I'm just too green and have a very long way to go before I understand all this," or "I'm getting way too ahead of myself" on this, please.  Somebody correct me because this is very scary stuff for a future twin jet pilot to hear.

Why?

Because!  How many OTHER airports will somebody end-up being the Lab Rat on discovering a new "ILS" problem?

Man, I hate hearing stories like this... this does not build confidence - not at all.  Somebody please tell me I've got it all wrong. 
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« Reply #55 on: March 26, 2009, 02:27:23 PM »

Please tell me that "I'm just too green and have a very long way to go before I understand all this," or "I'm getting way too ahead of myself" on this, please.

What he said.. er.. typed.  Smiley
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SJ30
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« Reply #56 on: March 26, 2009, 03:40:44 PM »

Well, I'm not a pilot and I appreciate that you've invested a lot of your time and money in very sophisticated equipment but it can be quite helpful to look out the window once in awhile, just to see if things are running, you know, smoothly.
 
You can never do enough cross-referencing and such.   evil

Roger, that!  I hear what you are saying, but what these guys seem to be discussing from a technical standpoint is quite different, indeed!   shocked

From what I've been reading here, these guys are talking about an outside influence such as ILS equipment and geographical (read: terrain) features, determining the outcome of what would otherwise be a normal precision approach that was well under the control and authority of the PIC.  That freaks me out, because it counters the very thing the pilot is trying to accomplish, namely, land the aircraft!   huh

So, for now, I'm confused and a bit troubled by what I'm reading here.  It would seem to me that once the FAA becomes aware of such ILS/Geographical/Terrain anomalies, that they and/or the airport officials would not merely throw up their hands, issue a "publication" and then tell pilots: "Hey, we told you there might be a problem."  Such an anomaly seems at the very minimum to be a super critical SOF [safety of flight] issue and should shut down that particular ILS system on that particular runway until the problem could be studied and removed.

Is it just me, or am I misreading this?

BTW - for the record.  I don't have the SJ30 yet.  It is part of a long-range (1-3 yr) plan which includes the accumulation of at least 1,500 PIC IFR hours in something that is multi-engine and high-performance, before I make the move to the SJ30 as the certified single pilot operator.  So, I've got some time to go yet.   smiley     

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Jason
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« Reply #57 on: March 26, 2009, 04:44:26 PM »

Are you guys telling me that some ILS equipment on the ground at some airport, or the geographical elements of the approach to a specific runway at said airport, could be causal for my aircraft doing something that I did not ask it to do while flying a precision approach? !!!!

Absolutely, the autopilot which is following the flight director, which is following the CDI will simply respond to any course deviation whether it is actually real or just a signal anomaly.  It doesn't know what's real and what's not, that's why the PF has to continually monitor the approach when coupled to an autopilot. Thus the push for WAAS and LAAS (GPS) approaches that provide CAT I like minimums. At the moment, that's an LPV, but in the future LAAS will allow CAT I or lower mins published as GLS PA. If you've flown a WAAS approach, you can see how much smoother and precise the needles are. No wiggly CDI and GS needles like on many ILS approaches.

On the CJ3, we'll often load the ILS frequency on both NAV 1 and NAV 2, but will display FMS on the PNF's PFD so we can cross reference the lateral course indications between the ILS and FMS.
« Last Edit: March 26, 2009, 04:46:49 PM by Jason » Logged
SJ30
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« Reply #58 on: March 26, 2009, 06:07:19 PM »

Absolutely, the autopilot which is following the flight director, which is following the CDI will simply respond to any course deviation whether it is actually real or just a signal anomaly.

Wow!  Amazing! 

Where I come from, this would be classified as completely unacceptable design theory/strategy.  To systematically link [AP to FD to CDI] and thereby exceedingly increase the probability of negative anomalistic input leading to an undesired result/outcome - by design - is bizarre.  I mean, if we know the CDI is pegged to the ground based ILS and we also know that the approach to landing is the most critical phase of flight [placing in to a high mission critical index] then how did anyone make the decision to proceed with such a auto-pilot driven design strategy?

I'm shaking in my boots.  Why?  Because this is not the first time I've heard of this happening.  This happened sometime in late 2008, and for the exact same reason.  Some problem with the ILS system causing external input into the aircraft which effectively took the aircraft out of the pilots control, at least temporarily.  And, I read about it happening again, in early 2008 and I think again sometime in late 2007.  These are just the times that I am aware of - I'm sure I don't know about all of them.  Wow!

It doesn't know what's real and what's not, that's why the PF has to continually monitor the approach when coupled to an autopilot.

How about just dump ALL AP approaches?  Just don't approve them.  At least until the design flaws can be logically worked out of the system.


Thus the push for WAAS and LAAS (GPS) approaches that provide CAT I like minimums. At the moment, that's an LPV,...

And, ironically, this was being worked on back in 2008 by IS&S for the PC-12.  Was is not a PC-12 that recently went down in Montana?  I'm not suggesting that it went down for the auto-pilot/LPV reason, but I just find the timing a bit ironic - that's all.

http://www.aviationtoday.com/categories/bga/26721.html


...but in the future LAAS will allow CAT I or lower mins published as GLS PA.

So, you are talking 200 ft minimums before the DA or the MAP?  I get confused - I'm so green, still.  I know I'm pushing things, but I want to take every opportunity to learn something I did not know before.  The DA and the MAP have always caused me some slight confusion.

I guess with the GLS [GNSS/GPS technology based] you get the vertical guidance and that would be a huge support tool for PA's, yes/no?

If you've flown a WAAS approach, you can see how much smoother and precise the needles are. No wiggly CDI and GS needles like on many ILS approaches.

I've yet to begin my dual.  That's why reading about this again is freaking me out.  There is a ton of high-performance twin jet instrument flying [especially coming home at night] in my near future and learning that I could be an ILS guinea pig because of some anomaly that should have never been allowed to persist into the system, is rather an uncomfortable thought to take into my initial training with me, to say the least.


On the CJ3, we'll often load the ILS frequency on both NAV 1 and NAV 2, but will display FMS on the PNF's PFD so we can cross reference the lateral course indications between the ILS and FMS.

But, that does not yield any vertical references does it?  The particular aircraft being discussed here was the victim of a vertical reference anomaly - is that correct?  So, how does [correct when I am wrong please] having two lateral references on two different screens, help with the vertical reference problem that ultimately causes the auto-pilot to increase pitch attitude too much?

Do I understand the problem correctly?  Again, I know that I'm still a babe in the woods here on this stuff.
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Jason
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« Reply #59 on: March 26, 2009, 07:48:33 PM »

I mean, if we know the CDI is pegged to the ground based ILS and we also know that the approach to landing is the most critical phase of flight [placing in to a high mission critical index] then how did anyone make the decision to proceed with such a auto-pilot driven design strategy?

Because we have pilots that monitor the autopilot and associated aircraft systems and avionics. If there was no one up front, I would also share some concern, but we have highly trained professionals up there doing their job. Reality is that autopilot issues, both system and navaid induced, are daily occurrences around the world. It is what it is.

How about just dump ALL AP approaches?  Just don't approve them.  At least until the design flaws can be logically worked out of the system.

What design flaws would those be? Pilots are responsible for monitoring the approach when coupled to the autopilot and also for recognizing potential issues where it may be best to disengage the autopilot and handfly (or reconfigure by hand and then re-engage). They don't exist everywhere, but they do exist at some airports. The NOTAM system is usually pretty good at publishing pertinent information that affects approaches, but it doesn't always work out nicely.

And, ironically, this was being worked on back in 2008 by IS&S for the PC-12.  Was is not a PC-12 that recently went down in Montana?  I'm not suggesting that it went down for the auto-pilot/LPV reason, but I just find the timing a bit ironic - that's all.

http://www.aviationtoday.com/categories/bga/26721.html

To be completely honest with you I see absolutely no connection or irony whatsoever.

So, you are talking 200 ft minimums before the DA or the MAP?  I get confused - I'm so green, still.  I know I'm pushing things, but I want to take every opportunity to learn something I did not know before.  The DA and the MAP have always caused me some slight confusion.

I guess with the GLS [GNSS/GPS technology based] you get the vertical guidance and that would be a huge support tool for PA's, yes/no?

I don't follow your question. On a precision approach, the DA is the MAP. LPV which is technically not considered a precision approach, even though it is in many respects more precise than an ILS, also has rock solid vertical guidance that is extremely useful. GLS PA's made possible by LAAS will only enhance the precision of both vertical and lateral approach course guidance.

I've yet to begin my dual.  That's why reading about this again is freaking me out.  There is a ton of high-performance twin jet instrument flying [especially coming home at night] in my near future and learning that I could be an ILS guinea pig because of some anomaly that should have never been allowed to persist into the system, is rather an uncomfortable thought to take into my initial training with me, to say the least.

Worst scenario possible, you execute a missed approach and request a different approach. No point in chasing a potential anomaly. It is a matter of correct identifying and responding to these errors in a timely manner that is of the essence.

But, that does not yield any vertical references does it?  The particular aircraft being discussed here was the victim of a vertical reference anomaly - is that correct?  So, how does [correct when I am wrong please] having two lateral references on two different screens, help with the vertical reference problem that ultimately causes the auto-pilot to increase pitch attitude too much?

It depends how it's loaded. The CJ3 is equipped with the Rockwell Collins Proline 21 avionic suite. You can load the ILS approach in the FMS, but you won't get any vertical guidance when FMS is selected on the PFD, but you can set VNAV to provide a synthetic glidepath that coincides with the actual glide slope angle which is found on the approach chart.  We can also do this when shooting visual approaches.
« Last Edit: March 26, 2009, 07:50:26 PM by Jason » Logged
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