Near loss of control, Never happened before.

[Aiden327]

Last night I had a pretty scary landing at KORD.

The flight was from KDCA to KORD. Estimated time 1:36, actualy about 2:00 with a 51kn headwind. Plane was the Leonardo SH MD-82

Takeoff was a bit tricky becuase of the weather.

KDCA 090852Z 33014G21KT 10SM SCT036 02/M03 A3019 RMK AO2 SLP222 T00171028 53008

With snow on the ground and the fact the md-80 is known for its icing problems I called for a ground De-Ice on the ramp after engine start. They proceded with type 1 and 4 fluid. After complete the flight controls were fully responsive. Being 3-4am my time I proceded to I direct take off doing a 30 second run up of the engines at 70N1 per procedure to clear de-icing fluid from the engines. Take off roll was supprisingly long but I didn't put much thought into it.

ZFW: 111710lbs
FOB: 26300lbs
GW: 138010lbs

Planned Reserve Fuel 8000lbs.

Estimated fuel usage was abut 18.3lbs.

Engine and Wing Anti-Ice was on the entire flight, fuel heat was used about 3-4 times every time the fuel dropped near 0c.

ATC assigned me visual runway 28 at KORD with the weather

KORD 091151Z 25005KT 8SM CLR M06/M08 A3025 RMK AO2 SLP255 T10611083 11039 21061 56005

About 5000 feet I went manual and completed the approach checklist. This is where I noticed the overhead annunciator panel was displaying "L ICE PROT TEMP LOW"

I opened the QRH and folled the checklist.

[quote]Associated PNEU X-FEED VALVE Lever ---- Open (Already Open due to after start-checklist)

Note: If at low engine power, advance power. (EPR and N1 Normal. No Power Loss)

Associated ICE PROTECT AUGMENT
valve c/b (if tripped) ---- RESET

[DaveSims]

Are you sure the elevators were not responding, or that you slowed down too much, almost to a stall or beyond, and couldn't raise the nose?  I question how much ice is the issue, because you only get ice in visible moisture, aka clouds or fog.  The weather you listed shows ORD as clear skies and clear visibility, ice should not be an issue.

Two things stand out to me.  One, the icing situation could have caused the pitot tube to ice over, causing a faulty airspeed reading.  Two, the correct action if you are descending a little too fast is to add a little power, not raise the nose.  Remember your basic airmanship, use pitch to control airspeed, power to control descent rate.  Simply raising the nose at those speeds without an increase in power will cause the aircraft to slow down, further increasing your descent rate.

[aeroart]

I agree with Dave that "8SM CLR" eliminates the possibility of icing because of the lack of visible moisture.

Just to add to his comments about the pitot tube freezing, when icing conditions actually exist, the static ports can also freeze over. In an airliner or any other aircraft equipped with heated pitot tubes, it is probably more likely that the static ports will freeze, particularly in freezing rain. Pitot-static operated instruments (airspeed, altimeter, and vertical speed) will be affected. The air data sensor will also be affected by frozen pitot tubes and static ports, and may have started the chain of events that lead to the crash of that Air France airplane into the Atlantic Ocean.

Art

[Aiden327]

Hmm, Ice doesn't occur even in sub zero conditions?

I weighed about 55 tons making my landing speed 135 knots. I was going 155 knots when I pulled back so I should have been way above stalling speed. Next time I will add more power.

So are you saying the pitot tube could have frozen over? All my gauges were in order and pitot heat was on. The failure that occored had to do with left wing de-ice temperature not pitot tube.

I will note that even though Chicago weather was clear I descended through overcast a bit higher up maybe 60 or so miles from the airport.

Thanks for the replies!

EDIT: According to the MD-80 FCOM Icing conditions are +6C and below and or a dewpoint within 3c of the temperature. Engine Ice is to be on at all times during these conditions and wing ice is to be on during visable moisture. The plane it self is said to have icing problems around the tail section. Could this play a factor?

[aeroart]

As far as I know, the only time ice can form without visible moisture is when the air is below freezing and supersaturated and there are no condensation nuclei around which the ice can form. I think this combination is most likely in the Arctic where the air is cleaner.

I suppose that the engine ice is to be on is because as the air enters the curved nacelle intake, its temperature drops to and below the dew point (just like in a carburetor), and ice can form there. I don't remember ever having ice form on the wings under the same conditions.

What I said about pitot tube icing was just to complete what Dave had mentioned. With no visible moisture and your pitot tube heaters on, I'm sure that pitot tube icing wasn't the issue.

There was a forum question about icing under similar conditions either here or on FlightSim.com some tme ago. I don't remember how it turned out.

Art

[Aiden327]

I have been doing a bit of reading, and it appears MD-80's have a major problem with ice and tend to ice up more then other plane's. The biggest problem I have read about is the tail section.

Don't get me wrong, I 100% believe you guys and understand why ice should not be able to form under these conditions.

I may have found my problem though. The tail de-ice on the MD-80 is inop when the wing de-ice is on and vice versa. I completely forgot there was a tiny push button to switch to tail de-ice. After re-reading the MD-80 FCOM I found a section that suggested operating tail de-ice every 15-30 minutes.

That said the only thing I can think of is I picked up tail ice when descending through the overcast about 40+ miles away from the airport and never cleared it.

Also, the approach into KORD was over lake Michigan. Would the air contain more moisture over the lake? Sorry for all the questions, weather is very interesting to me. I may take meteorology as a elective next semester if my college will let me.

[P51FAN]

You will probably find FAA Advisory Circular 00-6A - Aviation Weather For Pilots and Flight Operations Personnel interesting:
http://www.faa.gov/regulations_policies ... ntID/22268

[Aiden327]

Thank you for the link! Am reading it right now.

[GlobalHobo]

Before even reading the other replies, my first thought after reading your description of events was tailplane icing.

I know very little about the DC-9/MD-80. Real world I am a C-141/C-5/DC-10/737 guy. I can tell you from my 141/C-5 days that t-tails in and of themselves tend to be very susceptible to tailplane icing. If descending through clouds in icing conditions, we had the anti-ice on well before entering the clouds. (Of course, that went for my other airplanes, as well.)

Remember that the horizontal stab applies down-force on the tail in a stable aircraft. An iced-up stab will tend to cause a pitch-down moment. The nose will drop. That's why the landing procedure calls for a partial-flap landing: flap extension also causes a pitch-down moment. The fact that you were unable to pitch up either on approach or in the flare strongly suggests tailplane icing.

I do know that the elevators on a DC-9/MD-80 are un-powered. Ever notice the elevators flapping in opposite directions while it sits at the gate? They'll streamline once they get some air moving over them. If your servo-tabs were frozen, full-deflection on the yoke would have zero effect on your elevator. You did good carrying the extra airspeed. Without it you might have had a full tailplane stall and an unrecoverable situation. (Remember Colgan Air 3407? A Dash-8 T-tail. The pilot lost it after he deployed the flaps on approach.)

As for the idea of pitot-static icing, I doubt it. You had pitot heat on, and in transport category aircraft, the static port is also heated, so unless your airspeed readings were stuck at 270-300 knots (your cruise IAS), they were probably correct.

From FAA Advisory Circular 91-74, Pilot Guide to Flight in Icing Conditions:
There are a number of specific cues associated with ICTS (Ice Contaminated Tailplane Stall) to which a pilot should be sensitive, particularly during this phase of flight (approach and landing). Most of these cues are less readily detected with the autopilot engaged.
*Elevator control pulsing, oscillations, or vibrations (hard to sense in a desktop flight-sim!)
*Abnormal nose-down trim change
*Any other unusual or abnormal pitch anomalies (possibly resulting in pilot-induced oscillations)
*Reduction or loss of elevator effectiveness
*Sudden change in elevator force (control would move nose down if unrestrained)
*Sudden uncommanded nose-down pitch

That's my $0.02

As an aside, I am amazed at the sophistication possible in FS9/FSX. When I was first learning the craft, I practiced instrument procedures on FS5. It was crude, but it worked well enough. But practice system failures? Fuhgedaboudit! Now you've got transport-category aircraft, their systems and their aerodynamics all modeled in high fidelity. I regularly use the PMDG 737 to prep for recurrent. It's cheaper and it works better than the training software the company bought me! Whoda thunk it?

[Aiden327]

Thank you for your reply! I am now taking extra time to make sure my tail is clear before landing and takeoff. I had the same thing happen to me again but in a different case.

I was taking off Runway 1 at KDCA in below freezing conditions with overcast at 8000ft. I noticed my takeoff roll was extremely long, I was in the red lights before I rotated. As I rotated I barely gained altitude so I trimmed like crazy. A few exaggerated turns of the trim wheel seemed to fix the issue.

Immediately upon reaching cruise I pulled out my takeoff data and crosschecked my V1 VR and V2 speeds. They were correct. My trim was also correct to according to my trim charts. This has me really confused because I never had issues taking off in snow at KDEN and its much colder and higher altitude?

On an off note Globalhoba, I highly suggest getting the Leonardo SH Maddog. It is an amazing plane that simulates everything down to weather radar, terrain avoidance radar, icing, pneumatic, even circuit breakers. It has a realistic failure generator with MEL lists (you can set how many hours are needed for the plane to wear). It also features a proper loadsheet and has a amazing built in fuel planner. I also love it because you pull on cables more then hydraulics making it a challenge to fly.