Md-11 Lsas
 

I've been reading a little about this system and the manuals aren't real clear. I know the system will cause a nose down command if you are in a stall, but will it do it if you are in windshear.

I was thinking the same thing...

The answer is yes and no. "LSAS stall protection engages if windshear command guidance is on. If
windshear command guidance is off, LSAS stall protection should have
engaged earlier (amber PLI)" There would still have to be stick shaker first. If your looking at possible factors, I'd look at PNL. Keep in mind, you're only looking at 10-15 lbs. of force.

LSAS Does many things for the MD! I will break out the manual and spell them out once I have free minute.

Lsas
 

LSAS does command a lower pitch on landing, ie lowers the nose, when the aircraft is on the ground and the spoilers are deployed. It is to help prevent tail strikes. It is also off when airborne less than 100 ft AGL. So you could have a scenario with a bounce where it could get interesting.

Not so sure about that. A lot of inputs going into that system in this situation. I am not saying it was the cause but I think it could have been a factor in prohibiting a recovery.

Here you go! Number six is what people are concerned with!

Longitudinal Stability Augmentation System (LSAS)
LSAS provides:
1) Pitch Attitude Hold and Automatic Pitch Trim – With no force
on the control column, and bank angle less than 30 degrees,
LSAS holds the current pitch attitude. LSAS holds this attitude
by deflecting the elevators as much as 5 degrees. The
horizontal stabilizer is automatically adjusted to relieve the
sustained elevator deflection and maintain a full 5 degree
elevator authority.
2) Pitch Attitude Limiting – LSAS maintains pitch attitude to less
than 10 degrees of dive, or less than 30 degrees of climb.
3) Pitch Rate Damping – Increases the apparent static stability to
reduce the chance of over-control in pitch. It is active
throughout the flight envelope. 100% of max damping is
available above 20,000ft, decreasing linearly to 30% below
16,500 ft.
4) Speed Protection – If the autopilot is not engaged and the
autothrottle is not available (or able to maintain a safe speed),
LSAS Speed Limiting will engage to provide overspeed or
stall protection. LSAS overspeed protection is accomplished
by changing pitch. LSAS does not provide flap, slat or gear
overspeed protection.
5) Stall Protection – At 75-85 pct of the angle of attack required
to activate the stick shaker, the LSAS stall protection engages.
LSAS reduces pitch until the AOA is sufficiently reduced.
6) Pitch Attitude Protection and Positive Nose Lowering - During
takeoff rotation, LSAS provides Pitch Attitude Protection
(PAP) to reduce the possibility of a tail strike. During landing,
after spoiler deployment is commanded, LSAS initiates
Positive Nose Lowering (PNL) to assist in transitioning the
nose wheel to the runway after main gear touchdown.
LSAS is off when:
1) The autopilot is engaged
2) Below 100 ft RA, except active for pitch attitude protection
during takeoff and positive nose lowering during landing.
3) Bank angle exceeds 30 degrees
4) During manual trim operation
5) Pilot can override LSAS if, when below 1500 ft., more than
appx 2 lbs. of pressure is applied to the control column; or,
when 10-15 lbs of force is applied while PAP or PNL is active.
The pilot may counteract the LSAS overspeed or stall protection
by using enough manual force on the control column (appx 50
lbs) to defeat the LSAS inputs.
LSAS Switches
FAIL (illuminated)
-Control channel has failed, and has shut off
OFF (illuminated)
-Respective LSAS switch has been pressed, and the
corresponding control channel has been turned off.

Fedex MD11 software program load will be different than say UPS MD11, because of the adjustment to make it fly somewhat like the MD10. (Not!!!)

Just a couple of signs that others are thinking along these lines:

FedEx Jet Has Control Issues - WSJ.com

"U.S. and most foreign carriers phased out MD-11s from passenger operations partly because of their high fuel consumption and relatively short range. But some carriers, including Delta Air Lines Inc., became disenchanted with the plane's often touchy handling.

At one point, Delta's management took the unusual precaution of instructing all MD-11 pilots to manually fly the planes up to cruise altitude -- in order to better understand their handling characteristics. But with some software and other modifications, FedEx and other cargo carriers have come to depend heavily on MD-11 aircraft."

-and-

"Monte Thames, a retired FedEx pilot, said MD-11s were so notoriously "squirrely" to land that pilots routinely spent extra time in flight simulators practicing how to control the plane. "The MD-11 is one of those planes that can bite you real quick," said Mr. Thames, 62, of Germantown, Tenn."

then:

That Tragic MD-11 Safety Record

AN excerpt from a 2000 WSJ article (partially posted at above site)

"Yet sometimes, at low altitude, the opposite occurs: Pilots tell of pulling with all their might and finding the plane hardly responded. That can be a problem during landing. In several instances where pilots brought down their MD-11s too rapidly and tried to compensate at the last minute, they smacked the aircraft's tail on the runway or caused other damage.

That's what NTSB investigators reckoned took place in 1997 when FedEx pilots tried to land an MD-11 at Newark. The plane touched down too hard, bounced, rolled right, broke its right wing, flipped over and was destroyed by fire. The two pilots, who escaped, took most of the blame. But the safety board also raised questions about the plane's "stability and control characteristics," the design of its landing gear and why its wing broke off, a rare occurrence in similar hard-landing accidents."

Unofficial they all are, but I have been able to find numerous sources dating to before 2000 that were questioning of the MD-11 flight control system.

What's the saying - When there is smoke, there is usually fire.

I was editing my post as you posted this. Windshear+stick shaker would give a pitch down, but not windshear alone. At least this is listed in load 908.

I'm just speculating here, but what are the chances of the FAA finally making us split our fleet? MD-10s and MD-11s (two different bid packs).

Yeah but.........
 

Talked to a bud last night and he has an interesting twist on this. If you watch the video on the "initial" nose-gear touchdown, take notice how utterly violent that nose touches down. In fact, in reports from witnesses at the airport it blew "both" nose gear tires from the aircraft. By bud surmises this violent touchdown may have knocked both pilots unconscious, therefore you see the jet recoil back into the air, most likely due to the recoiling of the nose-gear strut on what was most likely a very lightly loaded MD-11 in a very strong headwind. With no conscious pilots to add power and administer a go-around, the jet continued a mini-phugoid and simply pitched back over to 4-6 degrees, impacting the runway again in tragic form.

Think about Dale Earnhardt at Daytona. It took very little G-loads but delivered in the right fashion to kill one of the greatest Nascar drivers ever. The initial nose-gear touchdown was nothing short of violent. I think my bud may have a point, and if the FDR shows no pilot input after they became airborne again, I'll be he's right.

Reference item 6 on that long list: PAP engages only if the spoilers are deployed. I don't see spoilers deployed in the video. That means the throttles were above the threshold for auto spoiler deployment (60% I think?). Maybe they were attempting a go-around...?

INTERESTING

This is an interesting theory. Does anyone else notice in the video that when the nose gear first touches down, the mains are already back in the air after their initial touchdown? After the nose bounces back upward, the mains touchdown again and bounce (the a/c appears to bounce a total of 3 times)...this view is obscured by the tail of the Thai aircraft, but look closely.

The PNL function of the LSAS applies 3 degrees of nose down elevator upon initial spoiler deployment (to assist in the nose-lowering task), increasing to 4 degrees once spoilers have deployed beyond 10 degrees.

I know Monte and he's a great guy. But he never flew the MD11. He was on the 72 and the A300, the last ten years on the A300.

Take a look at this link. Its another FX MD11 landing in NRT in what appears to be similar wind conditions (nice job btw). Look at the touchdown. Its a nose high attitude but as the nose is being lowered the mains are not yet firmly on the ground. It appears that its almost at a 3 (4 point?) point attitude when the mains are finally firmly on the ground and then it almost looks like a bit of porpoising after that.


YouTube - Crosswind Landing - by FedEx Express McDonnell Douglas MD-11(F) ?N587FE?

Yes, it's true that he while he never flew the airplane, is there anything in Monte's statement that is untrue or inaccurate? In fact, no. It's an accurate observation from someone who has been around Fedex, and, I believe, the training department, for a long time.

Just a little info about LSAS and WAGS. They are two separate animals.

LSAS works when the autopilot is off and you have less than 2 pounds of pressure on the yoke. It uses 5 degrees of elevator authority to command or hold pitch changes when there is no input from the pilot.
You do get positive nose lowering when the spoilers deploy on landing. That assumes that you are not holding the nose off the ground with positive back pressure during actual touchdown. That's why when we land you are suppose to release back pressure at 10 ft. to essentially a neutral stick. You can always override LSAS.
With regards to stall protection it will use it's 5 degrees of elevator authority to lower the nose to get away from the Pitch Limit Indicator (indicator of Vss/Vso). It will not, however, dump the nose to do this. Demos I've done in the sim show this to be a very slow process. I do not believe the nose down pitch you see on the video was caused by LSAS.
WAGS tells you when you are in windshear and provides you guidance on how to get out of it. If the autopilot is on (LSAS not working) it will follow the guidance, if the autopilot is off you have to follow the guidance, ie follow the Flight Director (again more than 2lbs of pressure on the yoke, LSAS not working). That simple.
Hope this helps.
Disco

Still, how does a retired Airbus guy get quoted in the media on? No retired MD guys out there to be found? Or do you think HE found the media? I guess he needed his 15 minutes! :rolleyes:

After watching the video the second or third time, I had a similar thought as you said. How VIOLENT the ride must have been.

With the length/arm of the MD-11 fuselage, the sheer size of the aircraft, and just watching how high it bounced it must have been just that, violent.

I'm sorry it doesn't address your question about windshear, but this information isn't in my manual, and I think its interesting. Rather than start another thread, I thought I would just post it here.


1.18.9 MD-11 Flight Control Computer Software Changes
In December 1995, the MD-11 FCC-907 software certification introduced a pitch
rate damper (PRD) control law to the previously certified LSAS. The -907 PRD utilized
inertial reference unit (IRU) pitch rate feedback in the LSAS elevator control laws to
counter pitch rate tendencies, thereby increasing the apparent static stability of the aircraft.
According to Boeing, this change was implemented as a product improvement to help
minimize MD-11 high-altitude upsets.94 Because it was decided during FCC-907
development not to affect the MD-11’s low-altitude, low-speed handling qualities, the
PRD was designed to phase-in and phase-out on a pressure altitude schedule (15,000 to
20,000 feet).
Boeing has developed an MD-11 FCC software upgrade—FCC-908—that was
FAA-certified on May 23, 2000. The upgrade primarily comprises modifications to three
subfunctions—PRD, pitch attitude protection (PAP), and positive nose lowering (PNL)—
of the LSAS. Boeing refers to these LSAS subfunctions as a low altitude stability
enhancement (LASE) package.
Boeing indicates that the LASE package implementation has two design goals.
The first is to employ the existing LSAS to provide deterrence against tailstrikes; Boeing
indicates this goal was established in response to the Safety Board’s Safety
Recommendation A-93-59. The second goal is to augment the natural aircraft longitudinal
handling qualities, via LSAS, in a manner approximating the handling qualities of the
existing DC-10. Both objectives are intended to facilitate a common type rating between
the MD-11 and the MD-10.95
The MD-11 FCC-908 software upgrade will activate the PRD control loop below
15,000-feet pressure altitudes at a reduced gain. Whereas the -907 PRD feature was
inactive at low altitudes, the -908 PRD will remain active at 30 percent strength from
approximately 17,500 feet down to takeoff/landing field elevation. Because the PRD
increases the apparent static stability, longitudinal handling qualities of the MD-11 will be
more like those of the DC-10.

The PAP subfunction is armed whenever an aircraft’s radio altimeter registers below
100 feet agl. The PAP uses radio altitude in conjunction with IRU pitch angle and pitch
attitude rate to provide nose-down elevator commands as a pilot begins to approach or
exceed the prescribed PAP pitch limit (30° pitch at 41 feet agl and 9.5° pitch at 0 feet agl).
This enhancement will slightly increase the control column force required to pitch the
aircraft beyond the prescribed limits, but the pilot otherwise retains full pitch-control
authority. As with all LSAS functions, the elevator command authority is mechanically
limited to 5° of deflection within the elevator electro-hydraulic actuator.
Boeing indicates that the PNL subfunction is intended to address both design goals
for the LASE package. The PNL subfunction provides a two-stage, nose-down elevator
command as the main wheels spinup for landing, which counters the nose-up tendency
typically experienced when landing ground spoilers are deployed. The PNL subfunction is
armed when aircraft radio altitude registers below 100 feet agl. The FCC signals, which
are used to command the auto ground spoilers to deploy, will cause the PNL subfunction
to command the first stage of the nose-down elevator of 3°. When the ground spoilers are
detected to be in excess of 10° of displacement, the second stage of the PNL increases the
nose-down command to 4°. Because the closed-loop PRD acts in conjunction with the
PNL, the nose derotation characteristics are essentially independent of the aircraft c.g. The
PNL commands are removed from the LSAS outputs at the same time that the flight mode
annunciator returns to the TAKEOFF mode (that is, after the nose wheel has been on the
ground for at least 20 seconds).

94 The Safety Board investigated some of these upsets, including the April 6, 1993, China Eastern
MD-11 accident at Shemya, Alaska, and the December 7, 1992, China Air accident at Anchorage, Alaska.
95 According to information provided by Boeing, the MD-10 is a modification of the DC-10 model that
was customized for FedEx. Like the MD-11, the MD-10 design incorporates a two-person flight crew
complement with associated changes to flight deck displays and system controls. The basic fuselage, wing,
control surface, flight control, and engine designs were not changed from those of the DC-10. On May 9,
2000, the FAA granted Boeing an amended type certificate for the MD-10 freighter. The FAA also approved
a common pilot type rating and landing proficiency credit for the MD-10 and -11, provided that the MD-11
incorporates FCC-908 to render its handling similar to that of the DC-10/MD-10.
Factual Information 50 Aircraft Accident Report
The PAP subfunction is being added to LSAS to mimic the tailstrike protection
that the MD-11 autopilot already provides for coupled landing and go-around operations.

Wow. So, they trick-f'd the -11 with software to make it behave like an MD-10, so they can get common type? I am sure Boeing pushed the snot out of this to the FAA because FedEx had promised to convert a ton of DC-10s...as long as it didn't cost them money (like having a separate MD-10 and MD-11 type rating/training program). It's starting to stink in here. :eek:

And if the dudes up front screwed up???

Not sure what you are getting at?

Wow dense = p =m/v

And if nothing wrong with the plane? 'cuz we all know this is gonna be the outcome...God forbid.,

Then we'll deal with those issues. Regardless, I don't like how the whole 11/10 common type thing went down. Do you?

Well, were you at FDX at the time this 'thing' went down? I have no issues with the whole 10/11 type. I do not believe it is any different than 75/76 or 74(multiple varients) etc

Well, good for you. Some of us do have a problem. Have a great day.

Yes, I was in the 11 program when this "thing" went down. No, I have never failed a check ride or line check in my career.

You sure are cocksure flying your keyboard.....that is disturbing.

727-100/727-200....different handling, same airplane. DC-10/MD-11....different handling, different airplane.

Haz, he is not worthy to banter with. BTW was that you in your avatar? Must have hurt.

I have to disagree here..... There is a ton of difference in the 75/76 and the 74. Especially dependent upon the variant of the 74. Even if you go with the 747-400 its is a whole different animal then the 75/76.

Schedule?
 

I find it strange that no one has talked about their (FDX80) schedule yet. I think they had two long legs with a CAN hub turn in between. I personally think this is way tiring myself. Now add the windshear and lack of sleep together; recipe for an accident IMHO. I can't tell you how tired I get on these "Optimized" trips now.

I brought up fatigue and scheduling a while ago, but was trying to stay away from the specifics of this specific mishap until more facts are known.

Generically, after a long day, the thought processes and physical agility are definitely slowed - and we can all agree that those weather conditions in general require everyone to be on their A+ game. Add in the potential of shifted circadian rhythm / multiple time zones and the natural process of looking forward to getting to the hotel as soon as the descent begins (I know we've all been there), and it starts to be really difficult to be an A+ player. Combine difficult environmental and/or aircraft conditions with one of those nights where you are comparing who had less sleep than the other in order to figure out whose leg it is going to be, and things get really rough.

2 hr flight from CRK to CAN (NOCAT), 3+ hr turn in CAN, 3+30 flight over to NRT to arrive at about 650am local for about a 10hr duty time

I thought they did SIN-CAN, then turned to NRT.

Pairing 112/15 ANC, unless it was revised it was CRK-CAN-NRT.

They definitely came from CRK to CAN and hubturned to NRT. Couple of former Subic (now Hong Kong) Captains jumpseated with them from CRK to CAN (JR and JF).

??????

Are you saying the 747-400 is a different animal than the 75/76. How so ? Not to be sarcastic, but I believe the original poster was comparing the MD 11 / MD 10 differences to those of the 757 vs. 767 or comparing the two MD aircraft to differences among the variants of the 747 Classic vs -400.

Another poster went on to say there is a difference in handling of the 727-100 "Stubbie" vs. the 727-200 "Stretch" and then concluded that the MD 10 and MD 11 were different in handling also.


Back to the LSAS issue, works good lasts a long time. In my short time at UPS, I've found the MD11 is a good hand flown airplane. It is very similar in my opinion to the 767-300. The exception, there is less roll oscillations (my poor pilot technique, I'd bet) in the MD11 than there are in the 767.

What I have observed is that the MD11 is usually hand flown to 3000 to 5000' on climbout, then hand flown again at 1000' HAT so LSAS is not really used often.

Quirky airplane ? Yep, IMHO stemming from the small tail and high approach speeds, a moving foot during banked turns, a tendency to pitch up on landing if autobrakes aren't used, autothrottles going to idle just prior to the flare, and an FMC system that uses FROM - TO logic vs. TO logic...which is frustrating for us Boeing types.

FF