OnCourse Software

Hi,
I was cleared so early, I got to my target altitude more than 100NM from my last way-point (using the descent rate set in the preset).
Attached are the log and the flight plan. I assume this is because there was a large distance between the way-points? But still why would the program not provide me more logical step descends far ahead into the flight?
Note I also did not get a warning from the program telling me the way-points were too far from each other.

Thanks

You will get a much better result with waypoints that are more evenly spaced, rather than the extremely long segment between HOLTR and BRIGR. Even so, your descent instruction was "at pilot's discretion" which means you do not need to start down at that time. You can begin your descent when you wish or when indicated by your FMC. (A descent instruction that does not include "at pilot's discretion" should be followed promptly.) PF3 does not give a warning if your waypoints are too far apart (other than your last waypoint being too far from the airport). A few other things: Your last waypoint is about 15 miles from the airport which is about as close as you can get without having vectoring problems. Anything less is definitely not recommended. Also you may want to try using the Extended Sectors File (selected at lower right on the screen where you load your flight plan). This was developed by a PF3 user and accurately reflects the ATC sub-sectors so you will get more realistic handoffs.

Dan77 wrote:

You will get a much better result with waypoints that are more evenly spaced, rather than the extremely long segment between HOLTR and BRIGR. Even so, your descent instruction was "at pilot's discretion" which means you do not need to start down at that time. You can begin your descent when you wish or when indicated by your FMC. (A descent instruction that does not include "at pilot's discretion" should be followed promptly.) PF3 does not give a warning if your waypoints are too far apart (other than your last waypoint being too far from the airport). A few other things: Your last waypoint is about 15 miles from the airport which is about as close as you can get without having vectoring problems. Anything less is definitely not recommended. Also you may want to try using the Extended Sectors File (selected at lower right on the screen where you load your flight plan). This was developed by a PF3 user and accurately reflects the ATC sub-sectors so you will get more realistic handoffs.

Thanks Dan but why did the program calculate this point as TOD? I got the automatic simulation pause at this point.
Isn’t the TOD calculated based on the descent rate defined in the preset?


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Shomron, you're really very good in finding all those little imperfections of PF3 quickly.

However, also this one can easily be handled.
As Dan said, you should have waypoints at a distance of around max. 50nm where your estimated TOD is for a better result. You can for example easily insert a user waypoint in LittleNavMap which PF3 then will use.
If you don't want to work on your flightplan, again as Dan already said, you are not obliged to descend when you get the clearance at pilot's discretion. And even when you are instructed to descent (without "at pilot's discretion ) you can start your descent at 200 FPM until you catch up with your planned descent path.

RALF9636 wrote:

Shomron, you're really very good in finding all those little imperfections of PF3 quickly.

However, also this one can easily be handled.
As Dan said, you should have waypoints at a distance of around max. 50nm where your estimated TOD is for a better result. You can for example easily insert a user waypoint in LittleNavMap which PF3 then will use.
If you don't want to work on your flightplan, again as Dan already said, you are not obliged to descend when you get the clearance at pilot's discretion. And even when you are instructed to descent (without "at pilot's discretion ) you can start your descent at 200 FPM until you catch up with your planned descent path.

This is what happens when you have used another ATC program for 10 years and got used to it
I guess with time I will understand how to bypass these issues, wanted to make sure I did not do anything wrong.
Another question about the descend at pilots discretion- if I forget to start the do I get reminded to start the descend descend (get an instruction I have to comply with) or I must start it on my own?



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As the guys have already mentioned, when you reached HOLTR your next waypoint was at a distance of 200 miles and so you were given the first step down as 'Pilot's Discretion' and yes, you would be reminded again about it if you 'forgot' to start your decent. If the altitude set at your next waypoint (BRIGR) had been 31000 (the same as HOLTR) then PF3 would have initiated a TOD descent somewhere between the two.

The reason PF3 paused was not because you had reached your calculated TOD, which by the way PF3 had that worked out at 112 miles, but because you started your descent from cruise due to your waypoint altitude configuration. So, in this particular flight, had BRIGR altitude been set at 31000 your TOD descent instruction would have commenced at about 112 miles from the FAF. Now that calculation is not set in stone and is changed on the fly (excuse the pun) dependant on your current speed, altitude and rate of descent settings. However, PF3's TOD is really for those who mess around with the altitude settings and put unworkable altitudes into their flight profile. i.e. If you HAD set BRIGR to 31000 that would have been deemed unworkable as it is only 15 miles from the airport! Hope that all makes sense.

As for your TOD in general, as in the real world, ATC really doesn't care or know anything about your TOD or FMC settings... they no nothing about either. Obviously they know they need to get you down in good time (safely) and I guess would use a rough 3 to 1 rule. But basically they are only concerned with aircraft/passenger safety, keeping you separated from other traffic and organising smooth handoff operations to the approach controllers.

No problem, that's what this forum is for.

You will get a descent instruction.