OnCourse Software

A real IFR flight plan cannot be accepted without waypoints between origin and destination. In 40 years I have never filed such a flightplan!!
If your IFR fpl is in ICAO you need at least three, ie. End of SID. Start of STAR and End of STAR. Almost without exception those waypoints will have altitude constraints. With regard to End of STAR any altitude constraint in QNH will take into account minimum safe altitude and distance to the FAP. So basically if you cannot get down to the altitude constraint of the Start of STAR or End of STAR then your flightplan is incorrect in as much as your cruise is set too high. Or, another problem simmers have is that they fly too fast too close to their destination which in itself prevents one from descending in a timely manner.

Flightplanning is a bit of a black art. And, too many rely on programmes like PFPX as gospel. These flightplanning programmes should at best be taken as a starting point only.

The whole point of waypoints is that they allow you to control and cross check your speed and altitude during your approach. If at any time you as Commander you feel that you should be descending now then you can ask PF3 for a lower altitude and recompute you flight plan profile. I'm afraid that even today with almost everything taken care of by the on board computers the crew still have to think about stuff. Being a slave to the magenta line as it were can and does kill!

Very good points. I accept them all!

I use simbrief for flight planning...PF3 does not accept its flight plan without putting up a warning about way points...now...this means that either simbrief is wrong...of PF3 can not accept real world flight plans...which is it?

mllgrennman wrote:

Very good points. I accept them all!

I use simbrief for flight planning...PF3 does not accept its flight plan without putting up a warning about way points...now...this means that either simbrief is wrong...of PF3 can not accept real world flight plans...which is it?

PF3 will accept simbriefs flightlans.

The warnings you get are if two waypoints are too close together. You can ignore this warning (in which case you may have a problem with a skipped waypoint, although i never have), or you can delete one of the waypoints from the .pln file. The choice is yours, but I suggest the former.

The one thing which PF3 and (PFE before it) does like is to have its last waypoint 30-ish nm from the airport.

Your last waypoint should and will probably have an altitude constraint. From that point tell PF3 what your FAP altitude is and where that is. PF3 will then tell you to descend to that point. If your last wypt is End of STAR then certainly there will be sufficient distance to descend to the FAP. At the last wypt you should be travelling at the required published airspeed and no faster. Descending to capture the localiser should be no more than 210kts and then you should slow down to 180 for the localiser. If all that is manageable then your next problem is how do I get down to the End of STAR. This will be made easy for you in that the whole STAR profile will be published. So in effect you only concern is to descend from cruise. Look at the distances involved and work out how quickly you can get down taking into account time and airspeed.

In the VC10 for instance the initial descent is made slightly faster than cruise of mach 0.84. At 0.85 with speed brakes open to about 25%. As you get into thicker air you shoot for 300kts max and then slowing down even further to say 250. The engines need only be reduced by about 5%n2 once flying to airspeed instead of Mach. And in fact in the 10 you can pretty much leave the engines alone for the rest of the ride. As varying amounts of washing will provide sufficient drag to match the required lower airspeeds.
To keep passengers happy on a long haul flight shoot for a 3deg. descent initially. Obviously having calculated the airspeed and rate of descent to achieve that.