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wana

Again, overspedd with MD-11

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Again ,with the problem within reclimb in SID climb.My situation is like this: after take off, AUTOFLIGHT, NAV mode and PROF mode engaged and aircraft configurated clean (aircraft configed throgh PMDG laod manager with TOCG 21-22). I am on a SID for example with a navaid limits FL128. The MD levels off at FL128 automatically until passing that navaid. when passing that point, it will climb again in accordance with the FMC settings until reaching my enroute FL.Problem is: at such FL, usually exceeds FL100, with all the things under FMC control and AUTOFLIGHT engaged, the speed (ECON CLB spee,d CI 70-80, usually 32xknots) is near the overspeed red tape, once the aircraft passing the SID altitude limit point and begin to take CLB throttle to climb again, it nose up with the IAS increases about 8-10knots above the FMC computed climb speed. SO, with the PITCH mode at FMA, the aircraft will further nose up to a vertical speed of 5000 or even 6000 to slow down the MD back to its ECON CLB speed, after that, speed and pitch angel stabilized as it should be during a normal climbout. During the above mentioned time, two citical issues: 1) As the ECON CLB speed is already near the overspeed red tape, with the +10knot during nose up, so far, I already received the OVERSPEED warning for two times during the nose up-down-stabilized phase in SID climbout. 2). VS above 5000ft/min(sometimes 6000 whem nose up after level off) is not OK for the passengers and I'v been on a real MD-11 flight with no feeling at all that the MD has conducted a expidite climb during the whole phase of flight(Thai International Reg No. HS-TMD , flight from Jakarta to Bangkok ) I don't know where the problem is and already referred to the PMDG materials. My friend also got the same problem with his MD too.Should i override the AT with joystick input in this phase of flight to prevent overspeed. With this problem, I careflly watched the ITTV cockpit video of MD-11 of Matinair, I can see the pilot only changed the MCP altitude setting as the ATC instructed, nothing more. My experience with FS is that, with the CWS and some other sophisiticated systems integraded in the flight management or control system(for Airbus is Flight Augmentation Computer (FAC) and the Elevator and Aileron Computer (ELAC), the complexity of the simulation software of these highly computerized aircraft is reaching a new high. So, with my heart, I want to say thank you to the guys in PMDG team and hopes a perfect MD-11 will finally be realized.I am not a native speaker, so, Sorry for my English and hope it can be understood.Anning Wong

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Hi Anning, your english is almost perfect and easily understandable!The problem with overspeed that you are experiencing would also happen in the real aircraft at light weight, low altitude, short step climbs and high cost index. It could be made worse in the simulation by add-on wind programmes producing windshear.In real life more use is made of 'Vertical Speed' mode to make climb transitions more comfortable, and in descent it's the most commonly used mode. This is because there are so many ATC constraints and orders requiring a new FMS profile calculation to be made that the computer often 'loses the plot'. You might be able to fly a beautifully elegant profile descent into Anchorage at 4 o'clock in the morning but not into LAX or JFK...So in your case climbing out of FL128 going up to say FL160 dial in 2000ft/min and use say speed 320/vertical speed mode.Chris G

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Hi Anning, your english is almost perfect and easily understandable!The problem with overspeed that you are experiencing would also happen in the real aircraft at light weight, low altitude, short step climbs and high cost index. It could be made worse in the simulation by add-on wind programmes producing windshear.In real life more use is made of 'Vertical Speed' mode to make climb transitions more comfortable, and in descent it's the most commonly used mode. This is because there are so many ATC constraints and orders requiring a new FMS profile calculation to be made that the computer often 'loses the plot'. You might be able to fly a beautifully elegant profile descent into Anchorage at 4 o'clock in the morning but not into LAX or JFK...So in your case climbing out of FL128 going up to say FL160 dial in 2000ft/min and use say speed 320/vertical speed mode.Chris G
MD requires a level of care and feeding for t/o and climb. I usually enter 250kts as an EDIT in the clmb perf page and select--then once I pass 10,000 (250KIAS restriction), I enter 270kts KIAS as an EDIT till cruise. I've got a few friends flying for Brown and Purple--MD-11 FOs--they either manage climb via VS or as I describe. Col (ret) Rich Perry, USAF

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Thank you all vrey much for giving me these helpful hints! I will try it and before that I think the use of VS mode or the IAS 270 or a speed lower than ECON CLB speed with Clamp mode in the altitude transition will be a good solution. Don't be lasy to hard over the MD totally to the AFS and do something to talk with my plane, haha!Anning Wong

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