by beaky » Wed Jan 19, 2005 12:59 am
I know it might seem crazy to suggest doing this when you're flying a heavy on an IFR route, but without GPS or any radio navaid in range (not to mention no inertial guidance system), you have to rely on deduced reckoning, or "dead reckoning". You don't need a giant swollen mutant brain to figure your approximate position, ETA, etc. via dead reckoning, just a flight computer. An old-fashioned "whiz wheel" will do. It's too bad FS9 doesn't have some sort of flight computer, although I think the flight plan might(?) factor wind in determining your mag. heading (not sure as I have only used the planner and nav. log a couple of times). It's also too bad you can't display the map with only your courseline and not the airplane icon, because then it wouldn't really be cheating to look for some sort of landmark (assuming you can see the ground in the sim). You might still drift a couple of miles off course, esp. if you've got variable winds along your route, but fuel permitting, a couple of miles here and there at 727 speeds isn't the end of the world. I have a question: does the route shown consist of any airways? It seems hard to believe that IFR routes would be built around VOR waypoints so far apart...
Looking closer at your follow-up post, I have a second question: if you knew you had a 40-kt west wind throughout the flight, and you were holding an accurate, constant heading while you had a VOR in range, how did you drift if you were holding that heading? No calculation required: "This heading has kept me crabbing along my true course line so far, so to compensate for wind, all I have to do is maintain this heading" Excuse me if you know this already, but VOR signals can't really be trusted at the extreme limits of their range. If you know you've been holding your heading
corrected for wind, and you see that needle deflecting when you're far from the station (according to DME), then that means you musn't start chasing it, it might be lying to you. I may be wrong about this (don't think I've ever been "in a hole" between VORs in RL or FS9), but I believe you can get a false reading even if the "flag" shows you have the signal, and you've got the Morse ident. Other factors (terrain, etc.) can affect VOR signals as well, esp. far from the station. Don't know if that's what happened, but... one of the rudimentary, no-tools-needed components of deduced reckoning is simply to stay with the heading that's been working so far. In that sense, even VORs are just a way of confirming your reckoning was correct.
