A question on 40 mile marker

[Guest klucznik]

Hi, While installing V3 I gave some thought to the 40 mile altitude and speed restriction stated by ATC. Here is my question: I am assuming that the 40-mile distance from ATC's FIX 'X' is determined by the shortest distance between your aircrafts present position and that point 'X' rather than 40 miles of actual filed flight distance. Is that correct? If it is then that could be a factor in determining point of descent, for me at least. I hope I worded my question clearly.Regards

[jd 57]

yes and no.when you are talking 40 miles from the airport, at which point you get switched to approach, yes, that is 40 miles direct the airport.if you are talking about the 40 miles where you are expected to be at your crossing restriction altitude, again, that is 40 miles direct the airportnow, here is the hairy part. one of the tutorials is kpie-kpie (i gre up in st. petersburg, had to include it). you will cross 40 miles from the airport on your outbound leg. up the coast, across the state, down the coast, back across the state and land. in this case 40 miles is direct the airport on the inbound/final leg.because of the introduction of the round robin feature in version 3, most distances relating to the final destination, is the sum of all the legs of the flight plan.i probably muddied the water, but heh. some one can clean it up... ;-)

[Guest Scott Campbell]

Blais,Just to unmuddy things a bit, when you are told to Cross 40 miles from xxx at 10,000/15,000 250 knots, that's along the plan route. If your last fix is not a VOR within 5 miles of the airport, then ATC simply tells you he needs you down to 10,000/15,000 in 30 miles or less. That's also along the route.V2 was direct-to-fix distance.However, it'll be obvious when you try it and you'll know what the distance is - along the route or direct.

[Guest klucznik]

Thanks GuysGood Wishes

[ConstVoid 112]

Excellent! That makes entering the speed/altitude restrictions in something like the PSS airbus a whole lot easier.Ian

[Guest]

For future reference...Neither real world nor RC controllers take specialty aircraft into account when issuing clearances. No special handling, except in cases of Emergency, Min Fuel etc... of course.The issue in this thread appears to be working out well, but there may be some come up where RC dosen't accomodate the way FMCs like to fly. We will not deveop RC, to accomodate FMCs! Not realistic. A clearance is a clearance. You as PIC should follow those clearances. Make the FMC fly by RC, not expecting RC to clear by the FMC.Respect to crossing restrictions, remember... you do have the "Unable" option :).