Descent rates

[slob driver]

Hi everyone,

Looking for some clarification on something. What is the minimum descent rate that atc wants to see on their scopes? Is it different in a terminal area i.e. 500 feet per minute versus 1000 feet per minute?

[husky]

There is no general rule. I expect rougly 5-800 fpm from a piston a/c, about 12-1500 fpm from a turboprop, and maybe 1500-2000 from a jet. Then there are all the other variables like differences in types, and the phase of flight (ie descending through FL380 and descending through 8000' on the downwind leg).

The only thing I ABSOLUTELY EXPECT is for the aircraft to do what it wants and to make any altitude restrictions issued or on the arrival. If I need a faster descent rate, I will ask for it.

[YYZJuice]

Most controllers are familiar with typical aircraft performance and expect you to climb/descend at a rate that is normal for the aircraft type. We can accommodate a slow descent if you let us know early that you will require it.

[slob driver]

Thanks much for the reply guys.

I am a little surprised that there are no minimum descent rates expected. I believe that in the U.S. atc expects a min. descent of 1000 fpm. Another pilot told me that atc expected a minimum of 500 fpm in a terminal area in Canada. I had never heard this.
The reason that I ask is as follows; In our FMC, it will calculate a vertical path to follow to make a crossing restriction, but after making the restriction, it may have a level flight segment. If we have been cleared to descend below the crossing restriction then atc expects us to continue the descent to the cleared altitude, however we would prefer to mimize our descent rate as much as possible to keep it as close to our calculated descent path as much as possible. Clear as mud?

[husky]

Thanks much for the reply guys.

I am a little surprised that there are no minimum descent rates expected. I believe that in the U.S. atc expects a min. descent of 1000 fpm. Another pilot told me that atc expected a minimum of 500 fpm in a terminal area in Canada. I had never heard this.
The reason that I ask is as follows; In our FMC, it will calculate a vertical path to follow to make a crossing restriction, but after making the restriction, it may have a level flight segment. If we have been cleared to descend below the crossing restriction then atc expects us to continue the descent to the cleared altitude, however we would prefer to mimize our descent rate as much as possible to keep it as close to our calculated descent path as much as possible. Clear as mud?

This is quite normal for aircraft to do, and will not cause a problem. If the controller needs you to keep going down after a restriction point, they will ask you to do so.

[invertedattitude]

Just don't ask for descent, get it, then readback " pilots discretion..."

[Gannet167]

I was cleared to be level 11,000' by some point. I started the descent and then after plugging it into the FMS, I needed 4500+ fpm. This isn't impossible but it is a little sporty, particularly when you need to to slow down for the 250 kts at 10,000. I don't know how ATC figures this stuff out and when I can I'm happy to help out and fit into the flow, but it'd be nice if ATC avoided this.

[Dees]

I agree, that sounds a little extreme, especially with passengers on board. Perhaps there was traffic in your way that prevented an earlier clearance. Maybe you were in your perfect spot in a sequence and a vector to get you lower, meant a vector for four other aircraft too. Tough to say what happened. My suggestion would be to let the controller know that this would be a tough crossing restriction and maybe they can negotiate a bit of a higher altitude with the controller in the next sector.

[husky]

We aren't perfect and make mistakes, the controller may have forgot to issue a restriction until past the ideal time etc...If the restriction is impossible, or might cause an excessing deck angle let the controller know.

[Maynard]

Does the same go for climb? climbing into a 60kt hdwind, holding barber pole at 500fpm (turboprop)