1000 FPM Descent?
02-15-2012, 10:00 AM
#43
Gets Weekends Off
Joined APC: Apr 2011
Posts: 1,547
I was a busy line check airman on the Embraer RJ for about three years. I enjoyed it. Anyway, one of the functions of IOE for a new hire is to learn how it's done out there. There are many, many situations that are not covered by company policy, FAR's, or the AIM. In those cases, typically, the IOE captain will show/teach technique that's typically accepted as the norm. He will usually demonstrate techniques that have worked for him over the years.
In my case, I tailor my descents to the situation at hand. If I'm up high and am given a pilot's discretion descent to some altitude that is well below my current altitude, I'll wait until I can come down at somewhere near 3000 fpm, initiate and establish my descent (smoothly - for passenger comfort), and then will reduce my descent rate as appropriate as I near the assigned altitude for comfort and regs (RVSM airspace, etc). This saves fuel, because it allows us to stay high as long as possible, considering passenger comfort, yet still gives an acceptable descent gradient at typical jet groundspeeds. Obviously 3000 fpm would be exceedingly steep in a turboprop, but in a jet it works out to around 3.5 degrees or so, which is fine.
If I only need to descend two or three thousand feet, then I will typically descend at 800-1000 fpm. No need to rush down and then immediately level off again, unless the controller needs it for some reason.
If the ride is bad down below, and I want to delay descending into that turbulence, but the controller has begun my descent, then I'll shoot for maybe 600-800 fpm, knowing full well that the controller may ask me to increase my descent rate for whatever reason he may need.
If we are in a terminal area, and there is no reason NOT to descend at flight idle, which will give us somewhere around 1700 to 1900 fpm descent at 250, then I'll typically descend at that rate. It makes the descent easy to manage. Of course, there might be any number of reasons to slow the descent rate - trying to stay out of the ice laden clouds below as long as possible, trying to stay above that 747's wake ahead, trying to avoid known turbulence, etc. In these cases, I'll descend at maybe 500-1000 fpm, as necessary to accomplish what needs to be done.
Anyway, these were always demonstrated or taught by me as technique, nothing more. During IOE, we would talk about these differences in technique and when each might be appropriate and why.
So, the answer is that you'll likely never be presented with anything in writing in these situations. It's simply technique.
In my case, I tailor my descents to the situation at hand. If I'm up high and am given a pilot's discretion descent to some altitude that is well below my current altitude, I'll wait until I can come down at somewhere near 3000 fpm, initiate and establish my descent (smoothly - for passenger comfort), and then will reduce my descent rate as appropriate as I near the assigned altitude for comfort and regs (RVSM airspace, etc). This saves fuel, because it allows us to stay high as long as possible, considering passenger comfort, yet still gives an acceptable descent gradient at typical jet groundspeeds. Obviously 3000 fpm would be exceedingly steep in a turboprop, but in a jet it works out to around 3.5 degrees or so, which is fine.
If I only need to descend two or three thousand feet, then I will typically descend at 800-1000 fpm. No need to rush down and then immediately level off again, unless the controller needs it for some reason.
If the ride is bad down below, and I want to delay descending into that turbulence, but the controller has begun my descent, then I'll shoot for maybe 600-800 fpm, knowing full well that the controller may ask me to increase my descent rate for whatever reason he may need.
If we are in a terminal area, and there is no reason NOT to descend at flight idle, which will give us somewhere around 1700 to 1900 fpm descent at 250, then I'll typically descend at that rate. It makes the descent easy to manage. Of course, there might be any number of reasons to slow the descent rate - trying to stay out of the ice laden clouds below as long as possible, trying to stay above that 747's wake ahead, trying to avoid known turbulence, etc. In these cases, I'll descend at maybe 500-1000 fpm, as necessary to accomplish what needs to be done.
Anyway, these were always demonstrated or taught by me as technique, nothing more. During IOE, we would talk about these differences in technique and when each might be appropriate and why.
So, the answer is that you'll likely never be presented with anything in writing in these situations. It's simply technique.
02-15-2012, 04:34 PM
#44
Gets Weekends Off
Joined APC: Feb 2010
Posts: 2,342
I fly a turboprop, so ymmv. I don't like to descend at flight idle for 2 reasons. Number one, oil temperature drops off and the oil is what provides ice protection for some areas. Number two, when torque drops below about 20%, the bleed air system switches bleed sources causing rapid changes in cabin airflow. I have noticed that the noises the change in airflow makes causes passengers look around as if something is wrong.
02-16-2012, 09:20 AM
#45
Gets Weekends Off
Joined APC: Dec 2008
Position: B757/B767
Posts: 180
I was a busy line check airman on the Embraer RJ for about three years. I enjoyed it. Anyway, one of the functions of IOE for a new hire is to learn how it's done out there. There are many, many situations that are not covered by company policy, FAR's, or the AIM. In those cases, typically, the IOE captain will show/teach technique that's typically accepted as the norm. He will usually demonstrate techniques that have worked for him over the years.
In my case, I tailor my descents to the situation at hand. If I'm up high and am given a pilot's discretion descent to some altitude that is well below my current altitude, I'll wait until I can come down at somewhere near 3000 fpm, initiate and establish my descent (smoothly - for passenger comfort), and then will reduce my descent rate as appropriate as I near the assigned altitude for comfort and regs (RVSM airspace, etc). This saves fuel, because it allows us to stay high as long as possible, considering passenger comfort, yet still gives an acceptable descent gradient at typical jet groundspeeds. Obviously 3000 fpm would be exceedingly steep in a turboprop, but in a jet it works out to around 3.5 degrees or so, which is fine.
If I only need to descend two or three thousand feet, then I will typically descend at 800-1000 fpm. No need to rush down and then immediately level off again, unless the controller needs it for some reason.
If the ride is bad down below, and I want to delay descending into that turbulence, but the controller has begun my descent, then I'll shoot for maybe 600-800 fpm, knowing full well that the controller may ask me to increase my descent rate for whatever reason he may need.
If we are in a terminal area, and there is no reason NOT to descend at flight idle, which will give us somewhere around 1700 to 1900 fpm descent at 250, then I'll typically descend at that rate. It makes the descent easy to manage. Of course, there might be any number of reasons to slow the descent rate - trying to stay out of the ice laden clouds below as long as possible, trying to stay above that 747's wake ahead, trying to avoid known turbulence, etc. In these cases, I'll descend at maybe 500-1000 fpm, as necessary to accomplish what needs to be done.
Anyway, these were always demonstrated or taught by me as technique, nothing more. During IOE, we would talk about these differences in technique and when each might be appropriate and why.
So, the answer is that you'll likely never be presented with anything in writing in these situations. It's simply technique.
In my case, I tailor my descents to the situation at hand. If I'm up high and am given a pilot's discretion descent to some altitude that is well below my current altitude, I'll wait until I can come down at somewhere near 3000 fpm, initiate and establish my descent (smoothly - for passenger comfort), and then will reduce my descent rate as appropriate as I near the assigned altitude for comfort and regs (RVSM airspace, etc). This saves fuel, because it allows us to stay high as long as possible, considering passenger comfort, yet still gives an acceptable descent gradient at typical jet groundspeeds. Obviously 3000 fpm would be exceedingly steep in a turboprop, but in a jet it works out to around 3.5 degrees or so, which is fine.
If I only need to descend two or three thousand feet, then I will typically descend at 800-1000 fpm. No need to rush down and then immediately level off again, unless the controller needs it for some reason.
If the ride is bad down below, and I want to delay descending into that turbulence, but the controller has begun my descent, then I'll shoot for maybe 600-800 fpm, knowing full well that the controller may ask me to increase my descent rate for whatever reason he may need.
If we are in a terminal area, and there is no reason NOT to descend at flight idle, which will give us somewhere around 1700 to 1900 fpm descent at 250, then I'll typically descend at that rate. It makes the descent easy to manage. Of course, there might be any number of reasons to slow the descent rate - trying to stay out of the ice laden clouds below as long as possible, trying to stay above that 747's wake ahead, trying to avoid known turbulence, etc. In these cases, I'll descend at maybe 500-1000 fpm, as necessary to accomplish what needs to be done.
Anyway, these were always demonstrated or taught by me as technique, nothing more. During IOE, we would talk about these differences in technique and when each might be appropriate and why.
So, the answer is that you'll likely never be presented with anything in writing in these situations. It's simply technique.
I agree 100% with everything you wrote. I'll only start down early if the ride sucks at cruising altitude. If I find a smoother level in the descent, I'll descend at 100FPM until it's time to resume a normal descent.
I was teaching a newhire a few weeks ago about the things to consider for vertical planning. Told him, the day you start to consider these variables and plan your flight path accordingly is the day you stop being just some button pusher, and start being an aviator. I think he was receptive.
02-16-2012, 12:56 PM
#47
Airport Hobo
Joined APC: Apr 2007
Posts: 844
Sure, but a few people have mentioned 3.0 degrees which is about a 3:1 descent. The thing is most airliners have some sort of vertical descent function in their FMS so it's not that hard to punch in something higher and more fuel efficient. The only time I hear about the 3:1 (or 5:1 for pistons) is for aircraft that don't have an FMS or GPS or if those fail.
02-16-2012, 02:35 PM
#49
The NeverEnding Story
Joined APC: Sep 2005
Posts: 7,611
Sure, but a few people have mentioned 3.0 degrees which is about a 3:1 descent. The thing is most airliners have some sort of vertical descent function in their FMS so it's not that hard to punch in something higher and more fuel efficient. The only time I hear about the 3:1 (or 5:1 for pistons) is for aircraft that don't have an FMS or GPS or if those fail.
If you are at FL310 200nm from destination and are given a pilot's discretion descent to, say, 11000 it doesn't take the Rainman to figure 31 * 3 = stay high until roughly 93nm out.
Folks who immediately initiate a 1000fpm+ descent in this scenario (which has been reported many times in this thread) obviously aren't taking 5 seconds to do the math in their head.
I love my VNAV-coupled 4.5° descents, but there's much to be said for being a PILOT and not an autoflight system manipulator. "Do some of that pilot sh!t, Mav" comes to mind...
02-16-2012, 02:46 PM
#50
Kerbal Rocket Surgeon
Joined APC: Dec 2007
Position: DTW 717A
Posts: 1,099
MAN I want to be a JET PILOT when i grow up just like YOU!! You're so awesome mister! Can I have your autograph?!
Seriously a bit condescending in your last 2 posts, drop the ego. You're not the only person in the world who knows the 3:1 rule and you're just as fallable as the next guy.
Thanks for the free instruction boss.
Thread
Thread Starter
Forum
Replies
Last Post
aircanada_addict
Flight Schools and Training
5
04-09-2006 12:44 PM
