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Shore Guy
16th Jan 2006, 20:12
American Eagle Saab 340B 5,000ft plunge: icing blamed

An American Eagle Airlines Saab 340B+ dropped rapidly from flight level 115
(11,500ft/3,480m) to FL065 due to icing, the US National Transportation
Safety Board (NTSB) reports.

The January 2 incident occurred as the aircraft (N390AE) was en route from
San Luis Obispo, California to Los Angeles International (LAX). No injuries
were reported among the 25 passengers, two crew and one flight attendant,
and the aircraft landed without incident at its intended destination.

The NTSB says the crew reported a normal takeoff and initial climb, and at
FL025 the captain gave control to the first officer with the aircraft's
autopilot engaged.

"As the airplane climbed through 11,000 feet mean sea level [FL110] the
captain noted light rime ice accumulating on the windshield wiper blades and
about 0.5in [13mm]-wide area of ice on the left wing," says the NTSB's
preliminary report.

It adds: "The captain began to reach up to activate the manual de-ice boot
system and the aircraft vibrated. The aircraft encountered ice and the
windscreen immediately turned white.

"The clacker and stick-shaker activated and the captain took control of the
airplane. The autopilot disengaged and the airplane began to bank to the
left in a nose low attitude."

American Eagle flight 3008 then began a rapid decent; the captain recovered
at an altitude of around FL065. The rest of the flight was uneventful and
the aircraft landed at LAX at 15:40 on schedule.

NTSB investigators note that the day before the incident, a flight crew
reported that the timer light illuminated during an en route de-icing
recheck, and that the de-icer failure light was later deferred "in
accordance with the operator's minimum equipment list". An appropriate
placard was placed next to the de-ice system control, and the auto cycling
switch was put into the 'off' position.

"Initial examinations revealed the airplane's deice system were operational;
however, the deicer timer failure light illuminated," adds the NTSB.

American Eagle was not immediately available for comment.

NTSB account: http://www.ntsb.gov/ntsb/brief.asp?ev_id=20060109X00033&key=1

jondc9
18th Jan 2006, 03:44
EVEN in warm california you can get ice... sometimes so fast you stall.

if you are in a cloud watch your OAT gauge (sat or whatever your plane has)

keep extra speed

keep autopilot off

keep all ice protection on...especially engine, prop, pitot/static etc


GET and GIVE pireps to know when icing starts and stops and where the tops and bases of clouds are.


jon

Keygrip
18th Jan 2006, 04:36
Flight level 025 and Flight Level 065? In California?

FIRESYSOK
18th Jan 2006, 04:51
"As the airplane climbed through 11,000 feet mean sea level [FL110] the


Well maybe on a standard day.

Strepsils
18th Jan 2006, 21:28
jondc9 keep all ice protection on...especially engine, prop, pitot/static etc

Good sentiments, but not always correct, especially not on the Saab. For instance, using the prop de-ice just because you are in the relevant temperature range has been proven to result in run-back icing. Better late than early is the message from Saab.

I'd take Jon's sentiments, but change his words to say use your de / anti - ice exactly as the manufacturer recommends.:ok:

jondc9
18th Jan 2006, 21:41
strepsills, thanks for the correction.

I do know one guy who was flying a metroliner (SA227) and let ice build up on the prop spinners/inlet. On short final to TVL ( south lake tahoe airport in california USA- elevation 6200'msl or so) he flipped on both de/ anti ice systems WITHOUTturning on engine ignition...both engines flamed out due to runback...but he made the runway...couldn't get either engine started to taxi~!

YIKES...similiar sort of engine to saab....different manufacturer garrett vs the GE company.

just be careful out there and it pays to check your de/anti ice systems on nice clear days...make sure they work then or write them up when there is plenty of time to fix them.

fly safe

jon

Micky
21st Jan 2006, 13:16
[QUOTE=jondc9])
keep autopilot off

Could you explain why keep the ap off in icing.
Is that good airmanship or is this dependet on AC type???
And if yes why?

Please explain

Cheers Micky

jondc9
21st Jan 2006, 13:47
Dear Micky:

regarding autopilot OFF in icing conditions. While you should certainly consult the aircraft manual, the idea is this:


if you tell the autopilot to maintain altitude or rate of climb etc, the autopilot is not really holding altitude, it is TRYING to hold altitude my manipulating the elevator.

if the wing gets iced up, the autopilot will have to work harder and harder to hold altitude UNTIL the elevator makes the wing get to critical angle of attack ( in England it is known as angle of incidence) and the wing stalls. now the plane is losing altitude and the dumb autopilot either disengages or continues to pull "up" on the elevator taking you deeper and deeper into the stall.
\
A human pilot would say: hmmmm, the plane is getting harder to handle, oops I can't hold altitude, better to trade altitude to get out of the stall and regain control especially with the wing's efficency compromised by ICE.


a tragic crash happened in America, near chicago when an ATR72 iced up on autopilot and spun out of control killing all aboard. YOU , as the pilot, must ask yourself ,'is it better to lose altitude and make a semi controlled crash landing (or better yet, escape the ice) and survive or watch the autopilot pull up and up till control is lost?"


please let me know if you understand this and be sure to check with YOUR flight instructor before you go charging off into the great unknown.


regards

jon

Huck
21st Jan 2006, 14:09
An autopilot in icing can also mask trim changes, including aileron forces. (In the Roselawn ATR crash they had "control snatch" in roll due to disturbed flow over the ailerons.)

If you are at a stable indicated airspeed and suddenly have to start trimming, and you're in icing conditions, I'd say the time to act is upon you.

If the autopilot is on, the worst thing possible will happen: it will trim and trim until it runs out of authority, then disconnect and say, "you've got it!"

Safety Guy
21st Jan 2006, 14:27
On aircraft equipped with leading edge deicing boots, a check of their function should be completed before any flight into icing conditions. A long time back, when I was flying a KingAir 100, we encountered similar icing conditions to those experienced in the Roselawn (Chicago) accident during approach into Milwaukee, WI. There was approximately 1/2 inch of ice on the unprotected surfaces as we made our approach. I was hand flying the aircraft and we were cycling the boots as per the KingAir manual. When I called for full flap on final approach (IMC), the aircraft began to pitch up as the flaps extended. I hit the forward stop on the elevator control, and the pitch was approaching 10 degrees nose up and increasing. I called for flaps up and slowly started increasing power. Fortunately the pitch up stopped and I was able to regain control. We retracted the flaps and continued our approach for a flapless landing. While I can't recall the exact number (it all happened pretty fast!), I believe I carried 140 to 150 kts down to landing to keep control.

When we got to the FBO, I climbed out and found that there was at least 1 inch of ice on the leading edge of the left horizontal stab. A function check showed that the boot was not inflating. After that, we had our maintenance guy stand outside the aircraft after engine start at home base and he did a visual check of the boot function. Not a perfect solution, but one more way to reduce the risk.

Shore Guy
21st Jan 2006, 19:03
In one of the more bizarre icing accidents I have ever read about, this King Air was unfortunate enough to crash, but fortunate in that everyone survived.In fact, most with minor/no injuries). I remember seeing the picure of this aircraft.....half in/half out of the building it crashed into. When it went through the roof, I understand it severed the pipes for the buildings sprinkler system, spraying the aircraft with water, which may have prevented a fire.

Abstract:
http://www.ntsb.gov/ntsb/brief.asp?ev_id=20020403X00453&key=1

Full report:
http://www.ntsb.gov/ntsb/brief2.asp?ev_id=20020403X00453&ntsbno=LAX02FA108&akey=1

jondc9
21st Jan 2006, 21:05
safety guy:

great story. in this age of IPODs and the like, it would be better to have nicer anti/deice equipment.

your story also highlighted one of the most important things about moving controls...keep your hand on the flap lever and if things are getting worse, move it back to where it was better. :-)

with all the security cameras that can be bought for such a cheap price, we as pilots should demand cameras/viewers so that we can see how our plane looks...especially controls/boots/etc.

jon

Safety Guy
21st Jan 2006, 21:13
It's only a great story because I was lucky enough to survive it! I'm sure glad I had my wits about me that day. A little tired or distracted, and I could have missed it until we were spinning in.:eek: It gave me a whole new level of respect for the effects of airframe icing.