Hello,what is your method of complying to ATC (approach) instruction such as "25 miles to touchdown" and adjusting your descent rate - do you compute it in your head, or there is some FMC trick that allows you to help yourself with that? I was a few times surprised by this instruction, and twice ATC had to adjust vectors because I was descending too slowly.. all bestJakub

I've never heard that instruction, I assume you're using RC? That's not a realistic instruction at all, see here:http://forum.avsim.net/topic/361525-radar-contact-instruction-how-to-program-fmc/page__fromsearch__1

Hi Noah,I don't use RC, actually this instruction was given to me by VATSIM controllers, last time by EGKK_APP, I also saw it on at least one STAR chart describing a CDA procedure. The thing is that the lateral path to touchdown is not straight (it was always issued to me when I was on the base leg, vectored by the ATC), so simple putting a circle 25nm around the t/d point would not work.

If it's RC4... it's just another way of saying at 40nm from the destination be at this altitude.Use the FIX button and enter in "/40" then press the button for it to get the code to enter into the LEG page... make sure you insert it into before and after the correct waypoints. Set the altitude required for that point and you're good to go.EDIT: You don't use RC4... just ask for a more specific instruction from ATC that you can understand. Nothing wrong with that.

Edited February 3, 201214 yr by wunderlicht

Okay I sort of understand, but I think that's a very odd instruction (even from you crazy guys across the pond). Are you still on the STAR/flight plan?I don't really understand what the controller is even requesting of you. If they just want you to expedite your descent, you could throw out the speed brakes/landing gear which will increase your descent rate if you are using LNAV or FLT CH mode. Or you could just look what your current verticl speed is, then switch to VS mode and manually adjust it, but you will still have to deploy flaps/speed brakes/landing gear to increase drag.

the best way to do it is: select the DEP/ARR page and then select the runway without any VOR/NDB/ILS -----this is called visual approach and then put in the distance your ATC cleared you on the next line. that's it!

This isn't a unusual statement to hear from real world ATC at all, but it isn't an instruction as such, what's happening here is during the vectoring part of your approach, where you no longer have as much ability to work out how many miles you'll be flying to gauge your descent as you are no longer following a star or rnav path, you might not have the spatial awareness of where in the pattern you fit. So are you going to be extended downwind say, or given an extended routing as you are number 10 for the approach etc, so might not be being vectored for a 10mile final but a 15 one. So what's happening is the ATCO is giving you an idea of how many miles you now have from touchdown, if at that point you don't think you can descend quick enough, and lose speed to be stable on the approach you should say you need further miles, a very very rough calculation is 3000ft for 10 miles, so if told 30 track miles you should be around 9000ft at that point.The idea behind it, is so you can perform a energy efficient, fuel saving, continuous descent approach. And by managing the energy of the aircraft should perform a throttle idle descent right onto the glide path with no need to level off. It saves fuel, less noisy, and makes for better chance of performing a stable approach. In the uk, virtually or major airports perform CDA approaches and controllers trained on how to assist in giving aircraft just that. These airports produce figures on how well not only the overhaul compliance is, but also individual airlines, for your info, Ryanair is one of the highest complying airlines!

That's not an instruction but infomation.Bert Van Bulck

Levels of ATC concern:"You have 25 miles to touchdown" - unconcerned, thinks you know what you're doing, just giving you an idea of what to expect. Nice."Are you happy with your height?" - mildly concerned, thinks you should be checking your energy on the approach."Slow down to XXX (200> at the least) knots" - genuinely concerned, giving you a definite speed to see if you can do it. Final check of your skill/sanity."Go around, maintain runway heading to XXXX', contact approach on XXX.XX" - given up on you, thinks you're clueless.:)

the best way to do it is: select the DEP/ARR page and then select the runway without any VOR/NDB/ILS -----this is called visual approach and then put in the distance your ATC cleared you on the next line. that's it!

Ahh, didn't think about that one - sounds simple and working and I will try this next time - thanks!

This isn't a unusual statement to hear from real world ATC at all, but it isn't an instruction as such, what's happening here is during the vectoring part of your approach, where you no longer have as much ability to work out how many miles you'll be flying to gauge your descent as you are no longer following a star or rnav path, you might not have the spatial awareness of where in the pattern you fit. So are you going to be extended downwind say, or given an extended routing as you are number 10 for the approach etc, so might not be being vectored for a 10mile final but a 15 one. So what's happening is the ATCO is giving you an idea of how many miles you now have from touchdown, if at that point you don't think you can descend quick enough, and lose speed to be stable on the approach you should say you need further miles, a very very rough calculation is 3000ft for 10 miles, so if told 30 track miles you should be around 9000ft at that point.The idea behind it, is so you can perform a energy efficient, fuel saving, continuous descent approach. And by managing the energy of the aircraft should perform a throttle idle descent right onto the glide path with no need to level off. It saves fuel, less noisy, and makes for better chance of performing a stable approach. In the uk, virtually or major airports perform CDA approaches and controllers trained on how to assist in giving aircraft just that. These airports produce figures on how well not only the overhaul compliance is, but also individual airlines, for your info, Ryanair is one of the highest complying airlines!

James, thanks for the extended info! Usually I had the impression that vatsim controllers overestimate the descent rate of 738ng, since after I assumed normal descend rate will be sufficient on base leg (throttle down, flaps 5, gear up), actually I should have used spoilers / extra flaps / gear down to match the descend path proposed by the approach controller. So I thought that maybe he was expecting me to expedite descent, by giving that information.

That's not an instruction but infomation.

Bert, thanks, you are right, although in the context of what I wrote above, I had the impression that it is something in between - maybe not an instruction, but rather a suggestion. Jakub

Ahh, didn't think about that one - sounds simple and working and I will try this next time - thanks!

That is for something different, I think sunxyang mixed this up with "Cleared for 25 mile final" which would this get you to.

Bert, thanks, you are right, although in the context of what I wrote above, I had the impression that it is something in between - maybe not an instruction, but rather a suggestion.

Maybe he thought you were expecting more trackmiles, and that is why you were higher than expected, by saying 25 track miles he expected you to revisit and correct you descend plan.