Requesting descent

[BigB]

Hey guys, thought I'd get some opinions/thoughts about requesting descent.

I normally like to request descent about 10-15 NM from my FMC predicated Top of Descent (T/D) point. I know that may seem a bit early to some controllers. The reason for doing so is that in the past, I've waited to the last couple of miles before T/D, only to have someone pipe up on freq with a massive request, or a controller giving a full re-route to a linguistically challenged foreign carrier. (Man I feel for you guys sometimes ). Anyways....as the guy mentioned above is on his 3rd attempt at the readback....Zinnnggg, there goes my T/D. The FMC tries to compensate by slowing down etc. It's normally not a problem getting back on the descent profile when finally being cleared lower if there are no Alt or speed constraints within a STAR. However, it becomes quite a juggle when there are constraints to be met....makes for a bit of an inefficient and uncomfortable descent.

The reason for my inquiry is because I overheard a Pilot and WG controller have a short but cordial discussion over this topic. The controller mentioned that for planning purposes, he prefered that the pilot start the descent as soon as his request for lower is approved (as opposed to waiting the 15 miles for the FMC T/D).

Personally, I love to have that "PD" tossed into the clearance.

Thoughts?

[Flying Low]

I would imagine that you could get the pilot discretion but you would have to request it. The controller will be under the impression that if you are requesting decent then you want to start now.

[zzjayca]

The problem is, when an a/c requests descent, a controller expects the a/c to descend ASAP. This factors into the controller's plan for other a/c in the area.

If you don't want to start down right away but are worried about not receiving descent clearance when you need it, say so in plain english.

Eg:
ABC: Center ABC would like to start down in ten miles.
Center: ABC maintain FL230 at pilot's discretion.

By letting the controller know when you are going to start down, the controller can factor this info into his/her plan and accommodate all a/c under his/her control more safely and efficiently.

[FamilyGuy]

Just to add a little more to this, when ATC says "ABC maintain FL 290", that is an ATC INSTRUCTION. In the CARS, pilots are to comply with all instructions received and acknowleged by them without delay.

The million dollar question is of course what is "without delay"? 5nm, 10nm, 20nm, 1 minute, 5 minutes??? I'd say a zero G pushover is as excessive as is 5 minutes, but somewhere in there is correct (given speed etc). When you don't want to find out is when something bad happens as a result of any "delay"!

Like was stated already, if you are setting it up early for FMS, request pilot discretion. Some controllers can get pretty ornery about things like this (and rightly so).

[BigB]

Fair enough guys. In the back of my mind, I always wondered what the controller was thinking when I wouldn't start an immediate descent.

Thanks for the response.

[ahramin]

Why not just request for a descent in 15 miles?

[ahramin]

I mean the descent, not the request, in fifteen miles.

[BigB]

I've always tried to keep my Tx's as brief as possible (without comprimising the intent). I guess that was the reason for my inquiry, just an interpretation of what I thought ATC ecxpected. On a super busy freq, you don't want to chew up too much time.

[FamilyGuy]

Short and breif to the point TX's are very welcome, especially when its busy. However, don't make it so short that you leave out key peices of information. That will only create more problems than it is intended to solve.

You have something you need to say, just say it. I used to be hesitant to tie up freqs too, but you and your needs are every bit as important as the next guys....