When I’m flying an IFR route using the autopilot the aircraft turns too late and then has to correct itself by intercepting the magenta line. I only fly the Kodiak and the WT CJ4 at the moment and it happens in both.
I think you’re right about the speed. It happens mostly at cruise and in sharp turns. Although I would expect a real autopilot to adjust for that and start the turn earlier.
To a degree they will.
The problem arises though, that by commencing the turn earlier they will be veering off the flight plan, and in some flight plans (mountainous terrain for example), that could prove fatal.
Seen the overshoot IRL sometimes. Used to go Hong Kong to Hanoi with a very sharp turn over Danang in a Tristar. (L1011) It could never make the turn at Danang without quite a bit of overshooting. Approach to Bejing RWY 18 had a similar turn, even the 707 couldn’t handle it without overshooting.
First, if you’re in that tight of terrain and relying only on the autopilot, you’re a fool. Second, veering off the flight plan is potentially fatal only when it turns you early? A late turn would be safer?? How, on earth, did you come to that conclusion?
Who said anything about later being safer?
It’s amazing that someone will imply something that was not stated or even meant.
This post had to do with proper speed management in order to stay on a flightplan.
I certainly hope if you fly IRL that you stay on your flightplan, and not stray from it, especially if that flightplan takes you on an arrival through mountainous terrain.
IRL, I’m not relying on a flight plan from preventing a CFIT, maybe an approach plate, but not a flight plan. And, if everyone stuck to the exact flight plan you’d have a lot more mid-airs for all those squawking 1200. Your eyes should keep you from hitting a mountain, not your flight plan.
The lateral oscillation can be caused by low(er) airspeeds, higher angle attacks and bank angle or a combination of both. A common example is attempting to get onto LNAV guidance (the magenta line) while climbing to cruise altitude.