I am presently in my 757-200 on the way to DTW. I was level FL310 for awhile and then the altitude began to vary between 30,920 and 30,940 ft. Same thing happened to me last night on another flight at FL370...altitude seesawed from 80 to 60 feet low. I wonder if this is caused by barometric pressure differences...but if so, why does the autopilot VNAV not compensate?#2- On start up last evening, I received an indication that the L engine X-BLD was on. I tried every overhead switch to alleviate that status but was unsuccessful. I could find no reference in the manuals either. It did not seem to affect the power- both engine readings were the same so I departed. Indication was present throughout the flight and a maintenance writeup found no fault. Wondering if anyone can shed some light.Thanks,Roger Curtiss

@ #2: Did you slew back from the gate? The xbleed warning has happenend to me when slewing after startup. Kind regards,Stephan Haaswww.lemont.nl/b767flightdeckhttp://www.pic767flyingclub.com/images/sas544.jpg

Stephen:You may have diagnosed this one right on the money. I believe that I did slew 90 degrees after pushback to get away from the terminal. I don't usually do that so that is a very likely explanation.Thanks.Roger Curtiss

Hey good info Stephan! I've been through this problem also, and used slew for pushbacks. Never thought this could be the reason!Ilan

RogerIn regards to your first question - I also have this problem intermittently using PIC and FSMeteo. It doesnt happen all the time, but the only way I found to get the AP to recapture the correct altitude is to adjust the Altimeter setting until it reads FL380 for example, then after a couple of minutes, set it back to the standard 29.92.This seems to work for me. I dont use any other aircraft other than PIC, so im not sure whether it is related to this package only or not.I currently use FSMeteo v6.4, but one of my fellow pilots in BAV also uses Active Sky and he experiences the same problem.I really cant put my finger on the cause of this one, but it can be very frustrating indeed.