Automatic landings?? If the aircraft is capable, the airline is approved and the crew is trained, they can be performed, but don't see who suggested the MD11 performs automatic landings as standard?

The MD11 actually does perform some beautiful auto lands, that DVD you have of Martinair shows one on arrival at Schiphol.

A/T on for landing can be dangerous if you experience sudden wind gusts and the ATS is pulling back the thrust to idle at 50 (or was it 47?) feet. Bounced landing, here we go...

A/T on for landing can be dangerous if you experience sudden wind gusts and the ATS is pulling back the thrust to idle at 50 (or was it 47?) feet. Bounced landing, here we go...

How would it be any different with manual throttle control? A situation such as that should probably follow with a go-around for safety reasons, regardless of autothrottle usage.

How would it be any different with manual throttle control? A situation such as that should probably follow with a go-around for safety reasons, regardless of autothrottle usage.

 

The computer has no idea what you are doing and going to do. If you lift the nose it only reacts after with more thrust. That's why every airline I know requires you to have manual thrust if you are controlling the airplane without auto.

See it like this: slightly gusty winds, ATS is spooling up and down to maintain the speed und you are riding down the ILS and disconnect ATS together with the A/P maybe at 1000ft. It's still ok to land, but you might idle the power later e.g. 30FT to adjust the wind changes affecting your airspeed. There would be no reason for a go around.

 

But with ATS on, it just reduces thrust to idle at 50ft regardless of any environment conditions which can result in a serious loss of airspeed before touchdown, resulting in a high sinkrate and a dangerous (especially with the 11) bounced landing.

The computer has no idea what you are doing and going to do. If you lift the nose it only reacts after with more thrust. That's why every airline I know requires you to have manual thrust if you are controlling the airplane without auto.

That is indeed the case (at least with Boeing aircraft), but (1) I am not sure this applies entirely to the MD-11, and (2) I was not referring to the general usage of autothrottles coupled with manual flight, but rather the use of the autothrottle in the scenario described by the previous poster.

 

I do not fly the MD-11 or know a lot about it, but based on descriptions from other people, it seems like the design of the MD-11 autothrottles system suggests that it should be coupled with manual flight.

 

See it like this: slightly gusty winds, ATS is spooling up and down to maintain the speed und you are riding down the ILS and disconnect ATS together with the A/P maybe at 1000ft. It's still ok to land, but you might idle the power later e.g. 30FT to adjust the wind changes affecting your airspeed. There would be no reason for a go around.

 

But with ATS on, it just reduces thrust to idle at 50ft regardless of any environment conditions which can result in a serious loss of airspeed before touchdown, resulting in a high sinkrate and a dangerous (especially with the 11) bounced landing.

If you know there is going to be a severely bouncy landing, you should probably go around. If you are using manual throttles, I don't think you should either apply more throttle or hope that no more sudden gusts will occur. I thought the autothrottles would correct for severe speed loss in the case of wind shear regardless of altitude (unless the flare has already begun).

Take a steady and strong headwind (no gusts, no bumps, no whatever), you'll experience the same problem.

 

Thrust Idle at 50ft > Airspeed loss > Bounced Landing

 

I know that this seems to be some kind of philosophy thing, some airlines have A/T on for APP and some say "if manual, then AP and AT off". To come back to the 11, the ATS pulling thrust to Idle has been identified to be one of the reasons for crash landings (together with the "character" of the MD-11 (LSAS, high speeds etc.).

For those of you running Windows8, are there any compatibility issues with the MD-11?

I could be wrong, but if my memory doesn't trick me, the main problem with the MD-11 resulting in bad or even disastrous landings is the flare manoeuvre. To be more specific, the execution itself, avoiding bounces, or not. :unsure: Stabilized approach beforehand? Yes, please.

 

Touchy elements from my perspective would be. The plane comes with a 'too' small tailplane setup, a very aft CG, a number two engine on top plus reverser and some spoilers causing a nose up tendency. Plus the high landing speeds adding kinetic energy to the game. Don't ask me about the actual severity of each item, but that's how I would look at the surely unique setup of the plane in general.

 

Now, while even the combination of those things won't prevent a safe flight and landing, it seems like it caused a hurdle for the crews at times. I recall writers summing up that the awareness about the vertical speed and the degrading elevator authority are vital elements of a proper MD-11 landing. While both things are also important on more normal setups, it seems like the MD-11 got described as being less forgiving. The bounce recovery training being very important and the tailstrike prevention also being a large factor on the MD-11.

 

I think the autothrottle system will start retarding the throttles at around 50ft RA. So that's a normal thing to happen. Do gusty winds change the setup? Yes, but, from the docs, only in the regard of the actual landing speeds going up as one adds the gust component to the Vref calcs.

 

I couldn't find anything recommending the MD-11's AT off in other than some emergency situations. However, if there's some source for that, go ahead. Me is interested. :smile:

See it like this: slightly gusty winds, ATS is spooling up and down to maintain the speed und you are riding down the ILS and disconnect ATS together with the A/P maybe at 1000ft. It's still ok to land, but you might idle the power later e.g. 30FT to adjust the wind changes affecting your airspeed. There would be no reason for a go around.

 

But with ATS on, it just reduces thrust to idle at 50ft regardless of any environment conditions which can result in a serious loss of airspeed before touchdown, resulting in a high sinkrate and a dangerous (especially with the 11) bounced landing.

 

 

Sadly the bounced landing has lost a few lives and airframes the past few years. All FedEx I believe

No, Lufthansa Cargo and Mandarin lost airframes as well as Sky Lease, Varig and others damaging airframes.

 

Fedex does have a Tail Strike Awareness Programme and later, I believe, another programme that addresses the bounce on landing.

 

Their 1996 programme states Autothrottles should be used for landings and will begin to retard after passing 50ft AGL. If the aeroplane flares early and the autothrottles are allowed to retard, the airspeed will decay, elevator effectiveness will be reduced, higher pitch attitude will be required making pitch-up tendency after touchdown more pronounced and more difficult to counteract.

 

Pilots should avoind holding off the aircraft to achieve a smooth landing as this will result in a long touchdown, heavy braking, a higher pitch attitude and reduced tail clearance. Below 10ft with the aircraft fully flared (sink rate of 2-4fps) the basic technique is maintain attitude by applying required control wheel pressure. A more advanced technique is to relax the back pressure approximately 1ft prior to main gear touchdown.

 

If a bounce occurs, a go-around should be initiated. High altitude go-arounds are initiated with pitch, while low level go arounds must be initiated with thrust. During low level go arounds main wheel touchdown may be unavoidable. The PF must not exceed 10 deg of pitch or retract the MLG until passing 20ft AGL with positive rate of climb.

 

Extract from Fedex investigation

A more advanced technique is to relax the back pressure approximately 1ft prior to main gear touchdown.

I remember reading that one was supposed to un-flare a B727 immediately before touchdown in order to produce a smooth landing, as the main landing gears were located so far aft. Is the same logic behind the technique described here regarding the MD-11?

A more advanced technique is to relax the back pressure approximately 1ft prior to main gear touchdown.

Will, the sentence doesn't make sense.

 

From what I've found, it should read.

A more advanced technique is to relax the back pressure to lower the nose (approx 1°) prior to main gear touchdown.

Now what they tried to achieve with that technique was the prevention of tailstrikes as the autospoilers with main gear spoolup caused a pronounced nose up tendency. However, after the Newark crash 1997, they've deleted that advanced technique recommendation and stressed that any nose up tendency after main gear touchdown should be avoided/countered and the nose wheel should be 'flown' smoothly to the runway.

 

Regarding the use of the autothrottle, it wasn't a mandatory item after (another?) revision any more. Note. This refers to the Fedex docs.

 

And another note. The plane helps the pilot with a system of the LSAS (longitudinal stability augmentation system), namely the pitch attitude protection (PAP) and positive nose lowering (PNL), by adding a nose down command to avoid tailstrikes. The latter does this in reaction to the ground spoiler deployment. The rough description of the first one would be that it limits the travel, marking the limits with a higher force being necessary to override the LSAS.

No, Lufthansa Cargo and Mandarin lost airframes as well as Sky Lease, Varig and others damaging airframes.

 

Fedex does have a Tail Strike Awareness Programme and later, I believe, another programme that addresses the bounce on landing.

 

Their 1996 programme states Autothrottles should be used for landings and will begin to retard after passing 50ft AGL. If the aeroplane flares early and the autothrottles are allowed to retard, the airspeed will decay, elevator effectiveness will be reduced, higher pitch attitude will be required making pitch-up tendency after touchdown more pronounced and more difficult to counteract.

 

Pilots should avoind holding off the aircraft to achieve a smooth landing as this will result in a long touchdown, heavy braking, a higher pitch attitude and reduced tail clearance. Below 10ft with the aircraft fully flared (sink rate of 2-4fps) the basic technique is maintain attitude by applying required control wheel pressure. A more advanced technique is to relax the back pressure approximately 1ft prior to main gear touchdown.

 

If a bounce occurs, a go-around should be initiated. High altitude go-arounds are initiated with pitch, while low level go arounds must be initiated with thrust. During low level go arounds main wheel touchdown may be unavoidable. The PF must not exceed 10 deg of pitch or retract the MLG until passing 20ft AGL with positive rate of climb.

 

Extract from Fedex investigation

 

I was talking about FedEx crashes like this:

 

http://www.youtube.com/watch?feature=player_embedded&v=V6cMK9LUnzI#!

Yes, and he was pointing out that other operators also suffered from MD-11 hull losses and may, like Fedex, run a tailstrike awareness program, from which he posted the details.

 

A very recent crash would be this one. http://en.wikipedia....rgo_Flight_8460 I think the Lufthansa Cargo folks in general can tell a story or two on MD-11 bounces and their outcome. :(