I was wondering (because of some problems with ATC not letting me descent on time) how this works in real life:

 

- does ATC tell you when to start descending or...

 

- do you ask ATC for permission to descend or...

 

- do you simply descent at TOD?

"Yes" to the first two and "never" to the third. If you're talking about a true, ATC-controlled environment, one should never begin a descent without permission, if not a directive, from ATC.

 

I'm sure others will elaborate, but that's the basics.

UK reply:

 

If you are inside controlled airspace receiving a control service from an ATC Centre then you descend when instructed to do so.

 

This would either be as a:

 

a) "Descend" instruction which you are expected to follow within approx 30 seconds, and usually at a rate of 500ft/min or greater (can't remember the UK AIP reference from memory).

b ) "When ready descend..." instruction, which is as it says - You are cleared to descend, when you are ready.

c) "Descend on the glide..." if on approach and established on the ILS.

 

a & b above may be accompanied with an 'expect flxxx level' to aid in descent profile planning purposes. I don't know if FSX ATC can do expect levels - not seen any yet.

 

Outside of controlled airspace, if receiving a Deconfliction Service, then I would expect you to descend only when instructed, as if you don't want to be controlled to that level, then you would be better requesting either a Traffic or Basic Service, and you may be being deconflicted against traffic at a lower level. Again, don't know if there are any payware tht can do DS/TS in the UK FIR in FSX.

In the US:

 

"Request lower" is a common phrase if you're at TOD and need to descend. Also at smaller airports or even big ones during slow times controllers will issue discretionary descents. "N12345, descend at pilots discretion, maintain 5000." It means you determine when you begin descent.

If Atc instructs you to descend shortly before TOD you can press the descend now button, the aircraft will pitch down but not too steep, maybe around -1000fpm, and it will intercept the planned descent profile and then increase vs to follow it, that way you can stay in vnav. You can do this on every flight actually to stop your passengers getting sick when you hit TOD and the the aircraft pitches sharply forward.

 

Iain