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MAJOR PROBLEMS WITH THE 757! May go back to the 777 -

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I am an experienced 777 sim-flyer. I have spent incredible numbers of hours in the 777. I read that manual twice. Now I have the 757 I have read that manual once. As expected, many similarities. I am haveing major difficulties with the 757. I am no dope - I could fly the 777 perfectly, & flying the 757 should be a task I can handle.Here are the problems:I flew from San Diego to LAX. I armed the VNAV before take off as it said in the manual. Initially it worked fine. I chose to disarm it at one point 7 the damn thing would never let me arm it again. I kept getting a message on the FMC that read: "Perf/VNAV unavailable". What the hell does that mean? :-mad I just had it working. No matter how many thousands of times I pressed it thereafter, still I got the same message on the FMC CDU.Next - I AM SURE THERE ARE BUGS WITH THE AUTOTHROTTLE SYSTEM! I know how to work them - I have them armed, & I press speed, it works intermittently! It never works consistently. Sometimes, I can't even get the SPD message to appear on the bottom of the EHSI, no matter how many times I press it. Not only that, It usually goes well past the limits in cruise. To add insult to injury, EPR won't light, & speed will often go to the "IDLE" message on the EHSI despite whatever I dial up in the speed window (even if I push the knob for speed intervention). The plane ineveitably approaches the stall speed.:-madFINALLY: WHenever I am asked to descent to a level in my moments before final approach (lets say 2000 feet), the alt hold remains lit & won't capture the glideslope - even if I have the appr & loc buttons pressed! It still won't disobey the alt hold feature! The only way I can trick it is to dial in an altitude of 0!!!!!!! Then it will capture the GS!Like I said, I am no dope. I am not a beginner. This should not be THIS difficult, especially after learning & MASTERING a much bigger plane like the 777. IS ANYONE ELSE HAVING ANY OF THESE PROBLEMS? Anyone have any suggestions?Thanks to all of you as always.Frustratedly,Chris Catalano

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Chris,I did some Fly!ing around KJFK this evening, exploring the new scenery I downloaded, and enjoying the colorful sunset, but, sadly, I, too, experienced the "PERF/VNAV UNAVAILABLE" message in the FMC CDU. It happened after takeoff, and I noticed that the temperature I'd set into the TAKEOFF data page had mysteriously cleared. I couldn't get it re-entered, but I attributed the loss of VNAV to operator error somehow. I'm still learning, and this is one seriously complex box. (I've got about 200 hours in the Fly!2K version of the 757, so I'm no newby, either.)My plan is to spend some quality time with the manual to unearth the cause...I was honestly taking shortcuts because I wanted to fly a quick hop around New York, and not putting my usual care into flight planning. I've never seen this message before tonight.I did fly the plane on LNAV with the ALT HOLD and A/T functions working perfectly well. Chris, I've seen you in this and other forums for as long as I've been here, so I know you're not a dilettante. Please take a deep breath and go back to the manual...you'll be in good company. That said, Rob and all at PMDG, it would be nice to have a table in the manual that explained what the various FMC alerts actually mean and what actions can be taken to correct them. This is amazing work, and I'm very, VERY sold...but extracting things from the narrative in flight can be tough!Kurt KalbfleischAmerica West Virtual P88

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Chris,Take a DEEP breath.... The product is fine. Read the manual carefully, one piece at a time. I too have recieved the PERF/VNAV function problem in the FMC. The VNAV and autothrottle fuctions are FAIRLY complicated as compared to a simple VS and/or altitude hold function. I have never touched an FMC prior to the 757. Recently after going through some triles and tribulations with the FMC, autopilot, etc. I have gotten fairly profficent in the 757 already. I am a licenced commerical-multi-inst rated pilot and flight instructor. I highly suggest you just put it down for a day. And fool around a little. You will begin to learn the "FLOWS" for the different systems your working with (autothrottle,FMC, etc.). I in my real flight experience I have NEVER used an FMC, I have only shot GPS approaches with in engine out. You just need to do a little more studying and some practice and it will work JUST FINE. :) Don't try to understand and master it all in ONE flight. I just mess around with 80% of the flight and really try to master 1 or 2 elements per flight. After about 10 flights or so you will have a pretty good handle of things.Yours Truly,CB

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Hi Chris,I'm not too sure about what happens AT-wise... At this point I can't comment.I'll try VNAV :If you get the message make sure :- the PERF page is correctly initialized (I'm sure you know about it already)- a temperature has been entered in the takeoff page( you can do this direct, or using the round knob at the right of the EICAS, next to the thrust lim buttons)- make sure you specified a thrust lim using those buttons anthonyAnthony MertonPrecision Manuals Developmenthttp://www.precisionmanuals.com

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Anthony,Aha! And I thought I'd done something wrong.In my case, when the "PERF/VNAV" error happened, I had entered all the data into the PERF page, including temp on the TAKEOFF page. I used derated takeoff power, selected VNAV prior to the takeoff roll, hit the EPR button at EPR 1.17 on the EICAS and completed a fairly nice takeoff. ATC had called for an initial altitude of 5,000 feet, and the plane leveled there. When I selected the next altitude of FL190, I got the PERF/VNAV message, checked the PERF page and TAKEOFF page and that's when I noticed the temp was not set into the FMC. When I attempted to reenter it, it wouldn't take, and I was left with manually setting the AT for the rest of the flight.Does that help?Kurt Kalbfleisch

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Anthony,For some reason, during climb, if you are not using VNAV early in the climb or drop out of VNAV and attempt to re-engage it, you will get the Unable VNAV msg and find that the T/O Temp number has disapeared from the performance page. Am I correct in understanding that I should be able to re-enter it if I select a temp with TMSP knob. I did ensure that I had climb power selected on the TMSP so that shouldn't have been an issue. I will play with a bit to see if I can figure when the temp is disapearing. Paul:-cool

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Same thing here. The VNAV Pref error also happend to me, The problem then is that you cant find out the reason. I have been flying the 767PIC for over a year and a couple hundred hours and i believe with the Boeing 757FMC manuals on my knees there should be no problem. But there is.MikePS The autothrotlle problem is also klnow to me. in idle mode there is a jerky feeling. it modulates beteen 0% till 10% thrust.

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When I selected the next altitude of FL190, I got the PERF/VNAV message, checked the PERF page and TAKEOFF page and that's when I noticed the temp was not set into the FMC. When I attempted to reenter it, it wouldn't take, and I was left with manually setting the AT for the rest of the flight.THANK YOU!!!!!! :-) I knew I wasn't crazy!!!!! (only nuts!)Can anyone solve this mystery?Thanks,Chris Catalano

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