Hey!I've just started the tutorial and my problem is i can't press the button for APU Bleed/Air!And running the Air System manually tells me at engine start procedure - "Start Air pressure low"I can't start the engines.Really worked exactly after the tutorial!

http://forum.avsim.net/topic/245586-you-must-sign-your-full-real-name-to-posts-to-use-this-forum-posts-without-names-will-be-deleted/I think the tutorial keeps the systems in automatic mode, and maybe your APU hasn't run long enought to be able to provide air.

Ok, it worked, but why it worked now the next time i started fsx it i don't know. I made everything right. Maybe i made a fire test at the wrong place/moment...?Beside I wonder why there are a few times in cruise alt - mode some faults in the PFD like unpredictable overspeed or altidude changes, which made my AP quite angry.Also i couldn't let the plane descend without the use of speed brakes(in the tutorial as not needed describted). but i think thats normal....Whats with the QNH. Normally it is to be set for the destination in the end of the descend for important reasons, isn't it?

Sir, (since I don't know your name), these are very interesting questions that we can probably give you the answer to. However, I would suggest that you review Dan's post in greater detail and read the link he attached and adjust your signture accordingly, or add the requested information in a subsequent post. Many people fail to follow these rules in their first post (myself included, awhile back), but its best to come around once you've been alerted to them. Cheers,

Sorry, but i did, just before posting my last reply - i added everything needed in "About me"Thought it's enough for administrative satisfaction to look after...?Ok, so i also added the specifications in old school signature now...for slow clickers.I understand,...But i am a bit concerned about till now only indications on my privates were made, although i've testes just in this moment five random members of "Todays Top posters" - everyone without his real name in his profile or a signature, few of them members for more than 2 years - and no admins obviously. So lets play a bit more fair...

As for the APU, as mentioned in automatic mode it will operate "automatically" after its running, but you have to make sure the N2 is at 100 percent on the engine page before you could use it for engine starting. Also, make sure you put the air system on "Auto" by manually pressing the Auto/Manual button. I believe that switch is in "manual" mode by default on. You might not be able to get the engines to start either if you are in the middle of an air system self test (not SURE, but I would assume you may not be able to). If you are running an annunciator test prior to engine start this could be an issue. Remember, holding the annunciator test button will trigger an air system self test so dont do it right before engine start. As far as the overspeed warnings in flight, this could be rapid changes in your weather. If you are using a weather add on make sure to smooth out all changes to weather. Im not totally sure of real world procedures, but as far as the QNH goes I would assume that the settings are more locally important around mountains/higher elevations than just at the destination in those instances where you are flying in elevated terrain, especially on approach.

Alex, Well, I'm not sure what to tell you about that. Yes, using your name is somewhat unusual in the Interent world, but we try to be cordial and friendly here, and perhaps that is in part because you use real names and don't run around flaming each other. The other forums don't necessarily have those rules. Sometimes I'll go into the FSX forum, for instance and see a bunch of unsigned posts, but I spend most of my time here, so it doesn't really bother me. Anyhoo, on to your questions. The wild changes in speed and altitude might be due to wind or temp changes in FSX. There's any number of posts here on how the FSX weather engine is mediocre, and that it can abruptly change. FSPUIC is the usual fix for that. The registered version offers wind smoothing. I'm one of the few who hasn't upgraded to registered (largely because I haven't been in front of my FSX computer long enough to buy the code), so I deal with the occassional random speed changes. If you want to stay that way, then you should turn OFF the "aircraft stress causes damage" box in FSX. The plane should descent without speed brakes, but often they will be necessary to descend quickly enough. As for QNH, it depends on what phase of flight you are in. I think the manual has some good detail about it.

HiQNH is the air pressure setting that will give you the field elevation above sea level. For example if you were at Heathrow and were to adjust the air pressure to give a reading of 80 ft (Heathrow is approx 80ft ASL) then that pressure would be the current air pressure. It is set so that you can set baro mins for your approach. QFE is set by setting an air pressure that will read 0ft when on the ground. This is often used in GA aircraft if your going to do circuits etc as it will give your altitude above the field. Eg if you set QNH at say Cardiff which has a field elevation of approx 220ft then flew a circuit at 1,000ft above the field your altimeter would read 1,220ft but if you instead set QFE then you altimeter would read 1,000ft.RegardsNixon Thomas

Ok, i think REX2 causes the changes in the PFD, i will see if i can fix that.With the air pressure i know that it is set to standard(1013) at transition altitude, right? and it schould to be set to destination pressure at descent or final or? otherwise my descend could be much to low or high, in extreme i could miss the LOC!?Or is this procedure made only at te advanced tutorial? Or does the FMC set the Pressure?

HiOn descent you also change the pressure at transition altitude and if you press B just below 18.000ft FSX will change it for you. The FMC is not used for this. Hope this helps.RegardsNixon Thomas

There is a brief explanation of Transition Altitude and altimeter settings on this wiki page: http://en.wikipedia.org/wiki/Flight_level"In the United States and Canada, the transition altitude is 18,000 ft. In Europe, the transition altitude varies and can be as low as 3,000 ft."TA can even vary from one aerodrome to another within the same country and these details are usually on the charts for the aerodrome. Altimeter settings in the USA are measured in inches of mercury, for example standard pressure in the Flight Levels is 29.92 inches. In Europe, the QNH is measured in Millibars/hectopascals, example 1013. The MD11 can facilitate a display in either measurement with a click on IN - HP button.Why? In basic terms, when an aircraft is lower and closer to the departure or destination airport, the local pressure is generally known through use of weather measuring devices, a barometer, and published in automated terminal information or other weather sources. Accurate altimeter settings are important for terrain clearance and vertical separation with other aircraft. If you are in instrument conditions (clouds) and using an instrument approach with published altitudes, the wrong altimeter setting can have bad consequences. You could be 1,000 feet lower than you think you are, and mountains do not duck down when a plane comes towards them ;-)Whereas at higher altitudes and over long distances, the local pressure may change frequently. Therefore, everyone uses standard pressure and this enables separation relative to other aircraft. It doesn't matter if aircraft A is flying Flight Level 220 (actual amsl say 21,500) and aircraft B, opposite direction of flight is FL230 (actual 22,500 msl) because both aircraft have one thousand feet separation relative to each other. Jets in the upper flight levels actually do small descents and climbs because on 29.92/1013, the autopilot will climb or descend the aircraft marginally as the local area pressure changes.Unfortunately, with the weather engines available for simulation, sometimes these pressure shifts are larger and more dramatic as the simulator receives updated weather details and instantly changes the simulators pressure settings. Somewhat like the abrupt wind shifts described that cause overspeed or stall conditions ... apparently out of the blue ;-)Hope this helps.Mike Sweeney