Go Back  PPRuNe Forums > Flight Deck Forums > Accidents and Close Calls
Reload this Page >

ATR 72 Icing & Loss of Control - Recovered

Accidents and Close Calls Discussion on accidents, close calls, and other unplanned aviation events, so we can learn from them, and be better pilots ourselves.

ATR 72 Icing & Loss of Control - Recovered

Old 17th Dec 2017, 18:45
  #1 (permalink)  
Thread Starter
 
Join Date: Apr 2006
Location: uk
Posts: 951
Received 15 Likes on 9 Posts
ATR 72 Icing & Loss of Control - Recovered

I cannot find any thread started at the time (almost exactly a year ago) of a serious incident involving an ATR 72, for which an AAIB report has just been released. .

the Conclusion was;

The aircraft suffered an in-flight upset at FL130 after accruing airframe icing during the climb, resulting in the adverse aerodynamic effect of ice build-up on the wings. The crew were presented with a degraded perf caution but did not action the relevant checklist because they focused on climbing out of the icing conditions. The IAS was not maintained at or above red bug +10 kt and control of the aircraft was lost when a turn was initiated in the lnav mode of the flight director.
I think it's worth a read, not so much for the technical issues but for the Human Factors elements of why the crew did what they did.

If it's been done already in PPRuNe, apologies for not finding it, please delete...

PS I found a mention in PPRuNe, but buried in Airlines, Airports & Routes
old,not bold is offline  
Old 17th Dec 2017, 19:00
  #2 (permalink)  
 
Join Date: Feb 2004
Location: USA
Posts: 3,367
Likes: 0
Received 17 Likes on 11 Posts
FYI:

https://aviation-safety.net/database...?id=19941031-1
bafanguy is offline  
Old 17th Dec 2017, 19:06
  #3 (permalink)  
 
Join Date: Jan 2006
Location: Between a rock and a hard place
Posts: 1,262
Likes: 0
Received 0 Likes on 0 Posts
The ATR does not seem to like ice very much:

Incident: Jettime AT72 near Bergen on Nov 14th 2016, drops left then right wing in icing conditions
172_driver is offline  
Old 18th Dec 2017, 06:08
  #4 (permalink)  
 
Join Date: Apr 2008
Location: Nearer home than before!
Posts: 524
Likes: 0
Received 0 Likes on 0 Posts
NNUTS. In anything other than a High Speed Jet Transport (or pehaps VERY high performance Turboprop), out climbing ice is a fool's decision. Always was and always will be.
RVF750 is offline  
Old 18th Dec 2017, 06:38
  #5 (permalink)  
 
Join Date: Aug 2005
Location: fairly close to the colonial capitol
Age: 55
Posts: 1,693
Likes: 0
Received 0 Likes on 0 Posts
control of the aircraft was lost when a turn was initiated in the lnav mode of the flight director.
With the potential of degraded performance, am I the only one that thinks they might have been better off actually flying the aircraft, or is this something peculiar to an ATR?
vapilot2004 is offline  
Old 18th Dec 2017, 08:02
  #6 (permalink)  
 
Join Date: Jan 2008
Location: CO
Age: 50
Posts: 47
Likes: 0
Received 0 Likes on 0 Posts
Bank angle limitations in severe icing conditions just released.
Domi is offline  
Old 18th Dec 2017, 10:43
  #7 (permalink)  
 
Join Date: Nov 1999
Location: UK
Posts: 2,468
Received 82 Likes on 48 Posts
With the potential of degraded performance, am I the only one that thinks they might have been better off actually flying the aircraft...........?
No, the QRH drill for severe icing - reproduced in the AAIB report - tells the crew to disconnect the AP (amongst other actions).
Uplinker is offline  
Old 18th Dec 2017, 11:46
  #8 (permalink)  
 
Join Date: Oct 2002
Location: London UK
Posts: 7,626
Likes: 0
Received 16 Likes on 14 Posts
Originally Posted by Domi
Bank angle limitations in severe icing conditions just released.
If I recall correctly the American Eagle ATR was in a holding pattern.
WHBM is offline  
Old 18th Dec 2017, 12:40
  #9 (permalink)  
 
Join Date: Jun 2000
Location: Australia
Posts: 4,184
Likes: 0
Received 3 Likes on 3 Posts
control of the aircraft was lost when a turn was initiated in the lnav mode of the flight director.
Flight Directors are an aid. To follow them blindly during inappropriate conditions is only asking for trouble. A universal problem it seems
Centaurus is offline  
Old 18th Dec 2017, 12:45
  #10 (permalink)  
 
Join Date: Jan 2000
Location: Asia
Posts: 2,372
Likes: 0
Received 1 Like on 1 Post
Flying slowly at a high angle of attack in a holding pattern with a cold soaked aircraft in icing conditions can cause grief.
Metro man is offline  
Old 18th Dec 2017, 13:02
  #11 (permalink)  
 
Join Date: Apr 2008
Location: nowhere
Posts: 1
Likes: 0
Received 0 Likes on 0 Posts
Originally Posted by RVF750
NNUTS. In anything other than a High Speed Jet Transport (or pehaps VERY high performance Turboprop), out climbing ice is a fool's decision. Always was and always will be.
Originally Posted by TangoAlphad
Agreed. It is one thing continuing a climb through icing etc but if you are picking up ice to the degree of being performance limiting unless you can already see patches of blue you probably aren't going to get through it.
Although most of my turborop experience was not in the area where I live, the area where I live is a well-known location for severe icing conditions in freezing rain.

A retired test pilot that I know did Twin Otter in flight icing tests. His advice was that the worst of the icing was actually in quite narrow bands several thousand feet thick.

Of course, each situation is different but in a situation where one cannot descend to air warm enough to melt ice or clear of both cloud and icing(ie no freezing rain), I would consider climbing first. In the case of a warm front, you may get to warmer air.

With regard to climb/descend options......When in icing conditions, you will always have the capability to descend but the climb option may no longer exist if you chose the descend option first.

At night, you will never see blue patches and if there is a higher cloud layer, you won't see blue in the day either.

As I said, this is not based on significant personal experience in such conditions and I'm sure others could give theirs based on more personal experience.
JammedStab is offline  
Old 18th Dec 2017, 13:52
  #12 (permalink)  

"Mildly" Eccentric Stardriver
 
Join Date: Jan 2000
Location: England
Age: 77
Posts: 4,128
Received 211 Likes on 60 Posts
I experienced severe icing once, in a Shorts 360 back in '86. The conditions had brought another one down some 48 hours previously, luckily with no fatalities. Airborne some 30 minutes, diverted, never reduced below climb power, and had the throttles firewalled coming over the hedge. Never try to climb above it, unless you are CERTAIN that you can clear the conditions.
Herod is offline  
Old 18th Dec 2017, 14:03
  #13 (permalink)  
 
Join Date: Oct 2011
Location: NV USA
Posts: 260
Likes: 0
Received 0 Likes on 0 Posts
Don't get slow in icing, if you do get slow don't turn, if you elect to turn use half bank until your not slow anymore.

The icing layer is rarely more than 3000 feet thick.
cappt is offline  
Old 18th Dec 2017, 17:22
  #14 (permalink)  
 
Join Date: Jan 2008
Location: CO
Age: 50
Posts: 47
Likes: 0
Received 0 Likes on 0 Posts
new OEB says HiBank only if IAS > icing bug + 30kts (30 !) in severe icing condition, otherwise LoBank - AND consider to descend to maintain the required speed.
Domi is offline  
Old 19th Dec 2017, 08:59
  #15 (permalink)  
 
Join Date: Feb 2011
Location: Leeds
Posts: 1
Likes: 0
Received 0 Likes on 0 Posts
Originally Posted by Small cog
The AAIB report says that the Captain was PF and was also LTC. Makes you wonder ...
Makes it even more likely for something to happen, Captain more or less single crew and watching what the other guy is doing, agree he should be used to being exposed those kind of situations but no one os infalliable.

I used to fly a type similar to the ATR, underpowered and a slow climber, even moderate collections of ice would cause large speed reductions and even require level offs to maintain min ice speed.

Its not an inherant problem with the ATR, if you fly a low powered aircraft with poor climb performance you are going to spend lots of time climbing through icing levels and if you get slow or don't follow procedures any aircraft in that catagory will bite you.
Livesinafield is offline  
Old 19th Dec 2017, 10:22
  #16 (permalink)  
 
Join Date: Oct 2004
Location: Germany
Posts: 63
Likes: 0
Received 0 Likes on 0 Posts
Originally Posted by Domi
new OEB says HiBank only if IAS > icing bug + 30kts (30 !) in severe icing condition, otherwise LoBank - AND consider to descend to maintain the required speed.
Not only against you but this whole is hard to believe.

Actually they did a test flight. They managed it to figure out the maximum level in ice =FL130. They stalled the aircraft at KIAS 165!

Manufacturer say >red bug speed< +10- what means 175 KIAS is recommended. That is 10 knots margin above actual stall speed.
The report cite a server ice CL- what demand minimum ice speed +10.. Is that to understand as (red bug speed/165 +10) +10 = 185 KIAS ?!
And dear Domi, never ever accept any >high bank< (what a term). Many flight directors have a small bug, omitting half bank in case pilot selecting >direct to<. You could choose pilot off FD or use a bank mode.

Generally is a lack in understanding the stall subject.
Lift oppose weight. But that is valid only under the premise, continuous unaccelerated flight.
The weight is mass multiplied by G-load. A = Mass x G-load
If you fly, like in this case, exactly at stall speed, any increase of G-load will immediate stall the wing. For that in ice, always fly above stall speed for ice, avoid any turns, avoid accelerations.Those is part of aviate, what comes before CL.
If a stall occur, reduce the actual stall speed. Push gently the yoke forward. That way you fly a ballistic curve, that reducing the G-load, that reduce the stall speed!
If a spontaneous roll occur, avoid big aileron inputs. That will increase the average angle of attack, of the aileron of outer/upper wing. That part will likely stall, aircraft bank to opposite side. (In our case reached 73°).
As you loose altitude/dive; airspeed will increase, so normal airflow should reestablish.
During recovering; likely to divert from given clearance and stall is to report as well as severe ice, if you anticipate over-stress aircraft need to report . But relevant call is PAN. Mayday is movie style as in Sullivan Movie, irl commander did no std distress call.

In conclusion, I would say, this report is to revoke.
rak64 is offline  
Old 19th Dec 2017, 10:46
  #17 (permalink)  
 
Join Date: Mar 2008
Location: Milano
Age: 38
Posts: 309
Likes: 0
Received 0 Likes on 0 Posts
Originally Posted by rak64
Not only against you but this whole is hard to believe.
The report cite a server ice CL- what demand minimum ice speed +10.. Is that to understand as (red bug speed/165 +10) +10 = 185 KIAS ?!
It's definitely to be understood as 185.
Your minimum icing speed, half bank protected, is increased by ten knots, if you want to fly full bank or NAV you need 10 knots on top of the new red bug.

The ATR is a piece of crap, happy not flying it anymore...
I-NNAV is offline  
Old 19th Dec 2017, 15:57
  #18 (permalink)  
 
Join Date: Oct 2011
Location: NV USA
Posts: 260
Likes: 0
Received 0 Likes on 0 Posts
If I remember right on the EMB-120 we used 210Kts min and autopilot off strongly recommended in icing. The autopilot off was to prevent control forces masking. We had similar loss of controls leading up to the min speed increase.
cappt is offline  
Old 21st Dec 2017, 11:04
  #19 (permalink)  
 
Join Date: Oct 2004
Location: Germany
Posts: 63
Likes: 0
Received 0 Likes on 0 Posts
You forgot about the fuel problem. If you stuck in ice, your cruising level is decreed, like in the here mentioned case, from FL190 down to FL130, the fuelplanning is not correct anymore. If not prepared for this you could easily land below minimum diversion fuel. 2 other reasons why fuel planning in ice is delicate. Performance in ice is less than in clean weather, less IAS with same powersetting, more FF for same speed. Early descend is needed and higher speeds/pwr-setting in descend needed. Maybe idle descent not possible because bleed air is not enough for cabin and deicing.

But all airplanes have limitations. The problem starts if you fly your current type like another type. You have to consider actual stall speed in ice could be high as 165 KIAS. (BTW, you can stall any AC at any speed, it depends on G-load). I've seen blackbox printouts from actual stalls of EMB-120 in ice that happens at KIAS 155. In C421 I experienced few at KIAS130. Laminar airfoil have tendency to stall at much higher airspeeeds in ice than clean.
Secondly manufactor recommend Flaps 15 as seen in CL, what indicated Fuselage create to much drag when maintaining higher AoA. (I remember the same for SD3-60, in case of engine failure.) Despite of CL airframe (fuselage) of ATR is not antiiced, or?
rak64 is offline  
Old 21st Dec 2017, 11:26
  #20 (permalink)  
 
Join Date: Aug 1999
Location: Hyeres, France
Posts: 1
Likes: 0
Received 0 Likes on 0 Posts
I wouldn't say the ATR's crap.....But no doubt it's got more than its fair share of gotchas.

I had about 1,400 hours on both 42 and 72 spread over about 15 years, on and off, and it was never amongst my favourites.

I never experienced the iceing incident we're discussing here, but I do remember during the TR being warned about it. However, if you've never experienced it and, like me, about the best you can remember how to deal with it is the page number in the manual, then I can have some sympathies for the crew here when you're faced with a situation you've never experienced before and you do what seems ' appropriate ' while your colleague is desperately trying to find the page in the manual.

And just a thought....If airframers can create and install the automatics for detecting problems such as this one and warn you on the various displays, why can't they extend that functionality to either display the instructions written in the Ops Manual or to automatically initiate the required actions and then inform the crew what and why the machine's doing what its doing through the displays with a simple ' accept ' or ' reject ' for the crew.

Within the grand scheme of things, that wouldn't be an impossibly expensive fit into new machines and , depending on the actual age / spec of the machine involved, perhaps also not an impossibly expensive upgrade to older machines.
Hussar 54 is offline  

Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.