Excessive Climb On T/O

[Guest regamuffin]

Hey guys please tell me im doing something wrong iv set the fms to perfection set the flaps thrust and stab trim but once iv taken off and on the climb out i switch the controls overs to the autoflight system with prof nav and fms armed, but for some reason it quickly climbs at like 30 DEGRESS nose up and like 5000 feet per minute and it like basically stalls its self my mates having the same problem too any ideas???.Paul

[scandinavian13 5,192]

Is the trim on your flightstick over-riding the trim of the autopilot?Sometimes when I fly the Queen, I forget to zero out the trim on my flightstick and I'll step away during cruise and come back to a stalled aircraft. If you forget to zero out the trim, any spike in the data from the stick will revert control to the trim setting on the stick. That might be your problem.Kyle

[Guest regamuffin]

Nope its not that that was the first thing i checked its only just the t/o transition to climb wont thrust is set to climb by the autoflight system it manages to sort its self out.Paul

[mburkhard 23]

Paul,is the autopilot following the flight director when this happens? The flight director should NOT go above 25

[Mace 1,904]

Check your FLEX value. I noticed if it's a little high, the MD-11 shoots up at a high rate of climb, especially if you are not particularly heavily loaded.FLEX is a tough on to calc I guess, without something like Topcat as is being discussed in the other thread.RhettFS box: E8500 (@ 3.80 ghz), AC Freezer 7 Pro, ASUS P5E3 Premium, BFG 8800GTX 756 (nVidia 169 WHQL), 4gb DDR3 1600 Patriot Cas7 7-7-7-20 (2T), PC Power 750, WD 150gb 10000rpm Raptor, Seagate 500gb, Silverstone TJ09 case, Vista Ultimate 64ASX Client: AMD 3700+ (@ 2.6 ghz), 7800GT

[Guest D17S]

The MD11 handles its initial TO phase a bit different than the 744. Notice the speed target remains at V2 until acceleration altitude(with PROF engaged). If don't want to just climb like a bat, arm PROF with your second button press after AF engage. That will allow Otto (via its pal, FMS) to nose over at accel alt. An accelation to your 1st speed limit will then occur with a reduced rate of climb. Get those flaps up. These events move right along. Seemed odd to me too, but so it seems, dats the way an MD11 works.

[3-2-1-Now 126]

Hi,I like the way MD worked this! Note that the aircraft will NOT pitch down and accelerate until you start retracting the flaps! The system will fly based on current configuration.I've still got a problem getting the AP/ATS disconnect switches working (but it is being looked into), but once you throw the Boeing methodology out the window, it is easy to grasp.Best regards,Robin.

[DLP084 5]

Hi, I had the same issue but thats the point, throw out the boeing logic. You have to leave the flaps out until you reach the accel. alt. When you retract now it works fine. "At or above acceleration altitude and flaps retract speed call "flaps up.""Jan-Paul

[Guest regamuffin]

so let me just clarify this your saying leave flaps out till acceleration point, but this is what i do anyways but i personally think the autoflight system is follow the fb well about 25 degress nose up last night i went all the way to 30 can we just explain this situation again just to make sure what i need to do to stop this bearing in mind it does it near enough on any sort of flex temp.Paul

[Guest D17S]

Watch the magenta speed target above the speed tape. On the initial roll it will be V2. IF an engine has not failed, on liftoff it will increase to V2+10. Prior to acceleration altitude, flaps retraction will not affect this speed, except in a very dangerous way. The V2+10 number is very close to the flaps 15 Vmin. As the flaps retract, the FMS will watch this Vmin and reset the target airspeed to a safe value if necessary, A Low Speed Protection event will occur. The speed target above the airspeed tape will turn white and reflect this new airspeed. It's a bad idea to allow this backup safety system fly the airplane for you. However if you leave the flaps at TO setting as you transit acceleration altitude, V2 will Still be maintained, only the AS target will turn white. Otto will continue to fly V2+10. To allow the acceleration altitude event to occur, press FMS SPD (not PROF, like you said, forget Boeing. I'm still trying). That will turn the white speed target number back to magenta and set the next Vmax (probably slat retract). The problem comes when the airplane is allowed to accelerate to beyond V2+10 prior to AP engagement. When the AP Is finally engaged, the airplane will decelerate back to V2+10. Sometimes it undershoots on the way down and all Hello breaks loose. Underspeed protection kicks in and it can turn into a real "E" ticket ride. For TO, a pilot Must control the airplane to at least V2+10's ballpark BeFore it's handed to Otto. Our pal Otto's pretty good, but he sometimes needs a little help from his friends.What to watch? *** The airspeed target above the speed tape. ***Airspeed is the controlling metric during the TO and climb phase. Speed on pitch. Say it again. Airspeed is being controlled by the pitch of the airplane. Thrust simply stays at either TO or CLM. - Speed - On - Pitch - . (On the other hand, the more things change, the more they stay the same)If you want to handfly. watch airspeed, Do Not use a pitch angle to control the airplane. Make sure you don't go crazy pitchin' up to slow to V2+10. Keep an eye on pitch angle for that purpose, but other than that, the flight director is just a pretty picture.So then, I agree, kinda. Leave the flaps at TO until you have accelerated away from V2+10. If you want the automated "Acceleration Altitude" feature to do this for you, press FMS SPD after AP engagement to arm this function.. . . and remember, focus on controlling airspeed with your pitch during that TO initial climb.

[Guest regamuffin]

Sam, You are god in my eyes lol, Thanks so much for that detailed instruction manual lol appricate ya giving the time for the explaination thanks mate.Paul

[emvaos 13]

Paul,For your first flights and until you get to grips with the enormous performance of this aircraft I suggest : (a) You arm PROF on the ground right after engine start. This is the normal mode of operation by the way. Fly the bars and engage the AP asap and see what it does (record attitudes, climb rates etc). Below the accelerationa altitude, by default 3000 ft above field elevation, the target airspeed is V2+10. Unlike Boeing airplanes there is no fancy energy management and rolling targets here (this advanced stuff is reserved in abundance for descend and approach :)).(:( Flex as much as possible (max 70 degrees). Even so at less than 200 tonnes take off weight you rotate **smoothly** all the way to almost 18 degrees. As you fly this powerhouse of a plane you'll get used to it. It is like a Concorde take off to theta 2 :)© Make sure that your joystick does not interefere with AP commands. Go to PMDG Options/Joystick Controls and set elevators/ailerons/rudder AP override to Never.Incidentally the default acceleration altitude corresponds to NADP-1 (Noise Abatement Departure Procedure type 1) which has you climbing at V2+10 all the way to 3000 ft above airfield. This entry is **editable** and totally unecessary for most airports in the world where you can start 3rd segment (acceleration to 250) at normally 1500 ft above airport elevation. Go ahead and edit entry (TO/APP page RSK 5) this unless your charts say otherwise.Hope this helps.Vangelis===================================== E M V Precision Manuals Development Group www.precisionmanuals.com=====================================

[Guest D17S]

The differences really are interesting. For instance, only PROF/NAV can be armed prior to TO. FMS SPD cannot. If PROF is armed for TO, the airplane will climb right through acceleration altitude while continuing maintain V2+10, then capture the first altitude restriction. (I was equating PROF to to the more all inclusive VNAV. That's an incorrect comparison). As PROF captures the 1st altitude restriction, thrust then retards to continue to maintain V2+10. Only after FMS SPD is armed will the airplane engage a speed target beyond V2+10 (sans a protection event). Now you can see why I use(d) 1/2 speed all the time. This really goes by fast in real time.The question is still, what's the RW button pushing drill? If I allow the airplane to accelerate beyond V2+10 and then punch in AF, the airplane will (aggressively) decelerate back to V2+10. I think this is what Paul saw, and what I initially found so "different." The airplane has real tenancy to overshoot into an underspeed protection event (especially if we noobee pilots retracted the flaps!). I also expect this is modeled accurately. This would also be a real world concern.So then, it's gotta be a no-no to engage the AP prior to the actual acceleration event (speed target increase). My observation is that it seems very unlikely that in RW ops, a crew would maintain V2+10 even to the acceleration altitude if all engines were running. If they are all still running, the airplane has already cleared the V2/engine-out obstacle and now wants airspeed. However if a crew wanted to engage the AP prior to this event, they would - Have - to keep airspeed at least near V2+10, or be prepared to: 1) Give away valuable airspeed,2) for useless altitude. 3) and risk a deceleration undershoot. It just doesn't make sense.The only conclusion I can see is that the AP is - Always - left out until After the acceleration event . . . and I'm not liking that conclusion much either. There's a Function there somewhere, I think I'm still just missing a Factor.Or, this IS a bit different. They really missed the boat by not scheduling that 1st/2nd segment "traveling" V2 sequencing.

[downscc 1,327]

On occasion I would set the acceleration altitude on the takeoff init screen to something like 1000 agl instead of whatever it is (which seems kinda high to me). Thus, she behaves in a much more congenial way and the climb to acceleration seems more "natural."

[Guest FrancoisH]

As it was said before, many procedure from airports in Europe include noise abatment and these procedure request the plane maintain the take-off configuration sometime up to 2500ft due to the high % of clibm requested... which is more than standard computed acceleration speed. On LFPG it's possible to ease traffic that airplanes maintain 10% of climb until FL150... this change a bit your profile I think.Anyway, you'll not overshoot the speed if you follow the magenta cross at take-off... it will give your right climb angle...And if you feel that acceleration is an issue, then you can just change the altitude into the FMC and the you go ?I don't understand your point there.