manual landing with autothrottle?

[ESzczesniak 128]

Guys, on the A3xx the auto thrust only automatically retards thrust during an auto land, if you are hand flying with auto thrust on it will (not) automatically reduce thrust during the flare!

 

I believe the 737NG's on the Boeing side are the same. I fly the throttles manually when AP is off, so I'm not 100% certain, but am pretty sure. Obviously on autoland, they also decrease to idle on their own.

[Rations 102]

I think we are doing the folks who are new to the flight sim community a great disservice by speaking in code in the forums. For example; RW ops -- what?

Welcome to AVSIM!

 

I think new users will be able to understand and appreciate abbreviations and acronyms (not really code) after observing the contexts of and reading forum content long enough, as well as participating in discussions.

 

Afterwards, using abbreviations and acronyms becomes convenient for both writers and readers.

 

For example, shortening terms such as automatic terminal information service (ATIS) and standard terminal arrival route (STAR) is very convenient and logical, as it saves space and time spent typing and mentally processing / reading.

[lodestar 186]

On MD11 is recommended to use manual thrust control in strong croswinds and windshear, otherwise you can leave autothrottle on(and i read somewhere that is recommended)when you do manual landings. In PMDG MD11 just don't forget to set your external hardware throtthle to idle somewhere between TOD and 50ft - if you don't, it may happen that autothrottle will not reduce thrust on landing.

On Airbus, you must reduce thrust manually during manual landing

 

p.s. i think that 737 don't have that function anymore, after Turkish Airlines crash at Schipol

Edited January 27, 2013 by B247NG

[Rations 102]

On MD11 is recommended to use manual thrust control in strong croswinds and windshear

I thought using the autothrottle in rapidly varying winds is recommended, as the flight computer can react quicker to environmental changes. I do not have any experience with the MD-11, so I may be incorrect.

[lodestar 186]

I thought using the autothrottle in rapidly varying winds is recommended, as the flight computer can react quicker to environmental changes. I do not have any experience with the MD-11, so I may be incorrect.

MD11 autopilot/autothrust are probably not stable enough in winds and turbulence. I can't find all that things right now, but here is something about:

http://airlinesafety.com/faq/faq9.htm

http://www.airlinepilotforums.com/cargo/9248-md-11-unsafe.html

[G550flyer 1,013]

Interesting. Was this the method recommended by McDonnell Douglas?

Actually, Mickey D only gave the text book flare procedure. The technique I mentioned came from experience. I picked it up while flying KC-10S in the Air Force. Military flying is full of techniques, good way to fill the experience gap when training a young force. You become a aircraft captain in the military quickly. The DC10 had a high range of weights. It would perform differently at hi, mid and lite weights. Another technique using 10% is break away thrust for taxi. 520k=52% N1 on 1 and 3.You never use #2 for taxi. You would start it and leave it at idle if you were above 500k. Other than that you start it at a point to ensure have 5 minutes at idle before takeoff. #2 causes issues for structures and buildings when running. It's angled down and the thrust is unaffected by ground friction like the wing engines. Another technique is 10% of gross weight plus 23 for a good N1 target on approach with flaps 35 on glide path. 400k=63% N1.

 

Back to the flare height. When the 10 is heavy, you have to pull the power earlier. It slows slowly when heavy. When lite, it responds to thrust change quickly. The heavy aircraft is easier to land. Pull the power late, and the aircraft gets a little floaty as the speed bleeds. The lite aircraft is trickier, you have to keep the power in longer. Pull the power too early, she will slow quickly and drop onto the runway firmly. It's easy to get caught in a cycle of landing either heavy or lite alot. Suddenly you get the heavy or lite aircraft and your landing is thrown off. A way around this issue is to use the 10% technique. It's a simple way to adjust your landings based on weight. We also flare off the radar altimeter call outs. There are few landing ques in the 10. You adjust your flare rate based on the rate of the call outs. We call it the cadence. If its fast, you apply at a quicker rate. If its slow, you apply slower. Basically, at flare initiate height, you pull power and pitch up to 6-8 degrees while shifting your aimpoint down the runway to visualize the sink rate. You slide your fingers up and grip the thrust reverse levers while maintaining cross wind controls. At touch down, the ground spoilers go to the 2/3 position which causes the nose to pitch up. You have to fly the nose done while lifting the reversers to the reverse idle interlock. As the nose touch down, the spoilers go to full and the reverse idle interlock is removed from the #2 throttle allowing full reverse use.

 

Another time we would experience the momentum effect is during receiver air refueling. The heavy aircraft were very sluggish to throttle response when moving fore and aft. Once in motion, it was sluggish to stop movement. You had to monitor the input in to judge how much throttle to take out. It was very easy to get in trouble when heavy. The key to the heavy jet was patience. Add a little, see what it does. Not enough, add a little more. Once she start moving, take a little out. Last thing you wanted was for her to get charging towards the tanker, it takes a moment to slow down. The medium weight aircraft was perfect. It had the right response to input. The lite jet was too responsive, very easy to over shoot input.

 

I miss flying it, but i have the PMDG MD11 to fill the need of a heavy 3 holer

[G550flyer 1,013]

I thought using the autothrottle in rapidly varying winds is recommended, as the flight computer can react quicker to environmental changes. I do not have any experience with the MD-11, so I may be incorrect.

One thing that was annoying in the 10 was autothrottles in gusty winds and moderate turbulence . I can't speak for the MD11 but the 10 had a 5 knot issue. Any time the speed deviated more than 5 knots from the speed window, throttles would go to the stops. 5 knots slow, they go max forward. 5 knots fast and they would go to idle. This would lead to the throttles jockeying back and forth. Annoyingly your body would rock in the straps. Anytime it was very gusty/bumpy, we just click em off and set a good power setting. During turbulence penetration procedures, there was a turb button on the guidance panel. Pushing it would disconnect the autothrottles and cause the autopilot to enter CWS(control wheel steering mode). This basically allowed you to set pitch and power while using the autopilot.

[kevinh 409]

Guys, on the A3xx the auto thrust only automatically retards thrust during an auto land, if you are hand flying with auto thrust on it will (not) automatically reduce thrust during the flare!

Good point. But then neither will the A/T on a Boeing.

[Rations 102]

Actually, Mickey D only gave the text book flare procedure. The technique I mentioned came from experience. . . . Military flying is full of techniques, good way to fill the experience gap when training a young force.

One thing that was annoying in the 10 was autothrottles in gusty winds and moderate turbulence . I can't speak for the MD11 but the 10 had a 5 knot issue. Any time the speed deviated more than 5 knots from the speed window, throttles would go to the stops. 5 knots slow, they go max forward. 5 knots fast and they would go to idle.

Thanks for the detailed information! I did not know that the DC-10 autothrottles had such uncomfortable behaviors. If the PMDG MD-11 were up to the standards of the PMDG B737, I might have used the money I have saved for the PMDG B777 or PMDG B747 V2 on it instead.

[G550flyer 1,013]

Real world ops.... Anyway, great post Rick

Thanks Rob

 

Thanks for the detailed information! I did not know that the DC-10 autothrottles had such uncomfortable behaviors. If the PMDG MD-11 were up to the standards of the PMDG B737, I might have used the money I have saved for the PMDG B777 or PMDG B747 V2 on it instead.

Anytime Owen. The autothrottles were great, only in very gusty winds when the speed jumps around alot did they chase. The PMDG MD11 is very nice though the engines feel a little sluggish when spooled. I adjusted mine a tad for better response. It's worth the purchase. One day we may get a realistic DC10.

[mburkhard 23]

I thought using the autothrottle in rapidly varying winds is recommended, as the flight computer can react quicker to environmental changes. I do not have any experience with the MD-11, so I may be incorrect.

Indeed, the computers are much quicker in adjusting thrust in gusty wind conditions, therein lies the problem; They are too quick! Meaning autothrottle on many different airliners would constantly adjust throttles up or down if gusts are present, which is useless and horrifying for nervous flyers as they hear engines spooling up and down constantly. So for that you need a human brain to smoothen things out. The MD-11's auto thrust isn't great in gusty winds, but so are many Airbusses I know of. Don't know of all the jets though, in my experience it is AT OFF in extreme gusty winds on approach. Even turbulence during cruise can render auto thrust useless. Seen that myself on an A330 couple of years ago.

 

Cheers,

Markus

[Rations 102]

Indeed, the computers are much quicker in adjusting thrust in gusty wind conditions, therein lies the problem; They are too quick!

in my experience it is AT OFF in extreme gusty winds on approach.

Thanks for the information. It would be interesting to compare fuel efficiency when using automatic vs. manual thrust control during gusty conditions.

[FLEX1978 373]

 

 

Thanks for the information. It would be interesting to compare fuel efficiency when using automatic vs. manual thrust control during gusty conditions.

 

We are talking final approach here, fuel burn in this kind of situation is not something that would even be considered by bean counters.

 

As Markus has pointed out, auto thrust will try to chase speed in heavy turbulence and gusty conditions. In cruise you would set turbulence penetration speed, set a specific N1 or EPR and let the airspeed fluctuate within reason, on final approach keep thrust changes smooth and try and maintain the stable approach criteria.

[Rations 102]

We are talking final approach here, fuel burn in this kind of situation is not something that would even be considered by bean counters.

I know. I am just wondering whether there are still—considering the extreme precision of modern commercial aircraft automation—common situations (such as gusty approaches) in which manual control is actually more cost-efficient than automated control is. (For example, manually managing speed to within 3–5 kt of target speed without the excessive corrections of the autothrottle seems better for the engines.)