![]() So upon receiving this clearance, the pilot would proceed direct to the given waypoint by engaging NAV (or, given modern nomenclature, LNAV). At some point after that, ATC would issue a clearance to proceed direct to a fix, and then the filed route would be flown from that point on. to join the WHOZT5 departure." In that case, shortly after takeoff, the pilot would select Heading mode and fly the specified heading. In the former case, the instructions might be along the lines of, "fly heading 120, expect vectors to JEBBB" or ". There are essentially two scenarios on departure: an initial vector, or flying the departure procedure track immediately "off the ground." ![]() The NAV feature is indeed rare, because most of the time you use FMS, not a raw VOR. The LNAV feature is used most of the time. It usually happens on busy airports on approach and on really busy airports on departure, but enroute it is rare. The HDG feature is used when the ATC vectors you around. It seems the autopilot HDG feature is used more often. You'd get a better result in something like IVAO where the controllers are played by real people. I am not sure how realistic the simulator ATC is and would't expect much of it. making the NAV button not very useful except when flying VFR without following. Your flight plan is usually not direct, but follows the defined airways.Įven in the simulator, if you use the built-in ATC, it will give headings that are not what the flight plan had expected. The ATC can also tell you to follow some radial of some VOR and that's where you use the NAV mode proper, not the LNAV mode used for following FMS. Sometimes also once on departure, but that's usually it. And even if the ATC wants you to fly other route, they will tell you new set of routes or fixes to use and you punch them in the FMS, so you still fly LNAV.Įxception is approach where it is common that ATC will have you fly downwind (opposite direction than the runway) and tell you to turn base and intercept the final approach, so there they will give you heading (and you use HDG mode on the A/P). In real life, most of the time you follow the flight plan. ATC will request you turn right or left somewhere around the waypoint you expected, but not where you or the NAV system would have turned. In real life, however, it seems almost a guarantee that ATC will provide some heading which is not necessarily the most direct route, ie. The FMS might provide "virtual vor" and use NAV mode too, but usually there is a separate LNAV mode for FMS. This is not the first time I have observed this "conflict" between FMC & Map.In flight simulator, using the NAV setting directs the Autopilot to follow the FMS' pre-setup flight plan and will navigate the aircraft through each of the configured waypoints. The image (based on AIRAC200811 from NavData) is for a flight YCFS - TUCAB - TUCKI - CG - YBBN (YCFS was YSCH in the ATR download AIRAC200410).Įxpecting the LNAV problem, I was flying with A/P on HDG when after passing TUCKI, the EHSI Map changed to show a track to the left whilst the FMC still listed the planned route.Įngaging LNAV on A/P, the aircraft turned left to this "misread" track !! WP=6,Int,ROLIR,ROLIR,45.1744,4.8436,0.00,71.0739,0.088,1,24484,Z46,00000,66000įurther to my earlier posts on this topic, I attach the image below which I believe shows that somehow the FMC is "misreading" waypoint data northbound - perhaps only in certain regions of the globe though (?). Then I switch AP on and the plane fly correctly during 3 minutes and started again to turn left to right. I had to disconnect AP to take plane under control. I've got AIRAC 802, and when I was inbound SIJAN the plane was turning left to right every time. LFMP SIJAN A27 MEN G53 MEZIN Z46 ROLIR LFLL I've got the same issue when I did a flight from LFMP to LFLL with route :
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |