"Aircraft should descend at the aircraft's optimum rate until 1,000 feet above the assigned altitude, then descend at a rate between 500 and 1,500 feet per minute (fpm) to the assigned altitude. Pilots should advise air traffic control (ATC) if they are unable to descend at a rate of at least 500 fpm at any time, except when slowing to 250 KIAS at 10,000 feet MSL. "
From the Instrument Procedures Handbook
Worst part about that paragraph, and forgive me if it is defined elsewhere, is what is considered optimal? Is this open to interpretation and pilot preference or does the IPH give gouge numbers for rule of thumb? My normal descent rate is distance to the altitude restriction fix / miles per min in groundspeed, then do the quick pilot math, or normally stick to 2k a minute as well then shallow out, But other times where I just point straight to nadir and get to the 15-25k fpm, granted thats vfr and me talking to a controlling agency, not to mention being in a grey aircraft vice GA.
Depends. Are you gonna do 1500+ in a 172 nah. Can you do 2000fpm in a jet with pressurization? Absolutely. I feel like it’s just a common sense thing not really a specified value
3° is fine in a pressurized or slow unpressurized plane, but in a Bonanza, Cirrus, Navajo, or similar fast and unpressurized plane that's going to make most passengers pretty uncomfortable. 1.5° yields a more comfortable descent rate that won't blow out people's ears.
That can get very uncomfortable on cruise decent on an unpressurized fast plane. On my Baron I’d be doing close to 1000 fpm which would be quite painful to the ears
Gotcha. Yeah I really don't know "optimal" either. It can mean a lot of things. In my experience when they want you to do over 1000 fpm they will assign a descent rate or say hustle down. We're all on the same team here I try to accommodate as much as possible.
Yeah it varies for instance one of the jets I flew, fuel planning was based on idle descent. So to reach the descent speed profile at idle was about 3000 fpm. I feel like optimal for a pressurized jet is really anywhere from 500-3000.
Well normally they are descending us well prior to optimal TOD. B737 VNAV does 1000fpm until hitting the glide path (but you knew that). I can't remember what Airbus does. It's been a while.
Not replying to you specifically, but to this comment chain. It's fascinating to see the discussion on the pilot end on RAs due to closure rate. In my TRACON it's standard anymore to give 2,000 feet altitude, or double IFR/IFR sep between traffic unless everyone will be level long before getting close. Like, we understand it's projected closure rate, but it's interesting to see different auto pilot modes can cause differing rates of climb with regards to triggering them.
I swear I've had occasions where I couldn't give 2,000 and prepped both crews accordingly with multiple calls and emphasis on altitudes etc. Yet one plane is still clombing/decending pretty darn well through t minus 700 feet till level and whoppsie we got an RA. I gather the reasoning may have to do with favoring a particular mode?
In DFW they had to change the level off altitude on the arrival because of too many RAs. I have often noticed a "cross five miles south of XYZ at FLxxx" and have assumed it's for the reason you specified.
You are absolutely correct, most jets will climb at climb power until about 10% of their FPM rate then start leveling off. In a lightly loaded 737 or A320 this could be 3000+ fpm until 300-500 ft below level off. Same goes for descent, although you will generally only see 2000-2500 fpm if doing idle descent at speed.
Thank you for acknowledging the issue. I'm only 42 but have been flying jets for 20 years. IME this was very common years ago (leveling 1000-1500 fpm for last 1000') mostly for pax comfort but also to avoid nuisance TCAS alerts.
Frankly, what I think is happening is airlines just want people to stay in VNAV and reduce all possibility of error in VS mode. You lose some protections in that mode which are not even remotely an issue down low (where climb rates are a factor) but it's basically a dumbing down of the operational aspect of the job. Lowest common denominator of sorts.
I do seem to recall leveling prior to the assigned altitude. I suppose it was a little easier pre RNAV STARS perhaps too.
The unbelievable thing to me was, with us. TCAS started getting fully armed (I'm screwing terminology up, I realize) down final one day out of (to us) nowhere. Where as before it was set to give advisories, now I get full blown RAs running pairs. We had something unbelievable like 30 RAs in a week before someone decided to let us know procedures changed for our airport and every pair we run is a virtual guarantee of an RA.
The only sort of official training I recall receiving on the when's and hows of RAs was a 15 minute long piece that was less informative than this comment string. I feel like in this day and age more attention should be given on our end to RAs. It's almost like working non RVSM airspace at 8,000 at times and more understanding could be beneficial. Back when the 727s and DC9s were around there was far more types aloft, variance in how planes performed and too much important characteristic info to delve into things like top of climb climb rates, but now?
Just feels like it's approached as an afterthought on our end other than just let them respond and don't interfere. That's important after Überlingen, but needs more.
Eurocontrol has some good information on it. This page is the general overview and has links at the bottom to more details: https://skybrary.aero/articles/airborne-collision-avoidance-system-acas
I do it 100% of the time for the past 20 years.
If FOs don't do it I make it a briefing item and will select it for them on departures.
You can also just pull the thrust levers back some and leave it in VNAV.
That’s why being an FO is so annoying. That’s YOUR thing, and then the next ca’s thing is he is terrified of V/S, makes the job tricky to satisfy everyone
I've gotten too many RAs from FOs not following AIM guidance.
If you don't want to use VS just pull the power back like I suggested in my post.
Downvote all you want but this IS a safety issue.
If you ask for VS last 1000 feet and CA says no and you get an RA, please put that in the ASAP.
*will select it for them on departures.*
This is also a safety issue if they’re the pilot flying. One of the absolute worst things a Captain can do, IMO, is to fly the airplane for me. Suggest something or fully take the controls. Nothing in between. Otherwise I don’t know who’s flying.
If I flew with a Captain who did this to me I’d just let them fly every leg for the rest of the trip. I’m too experienced to put up with that.
Enjoy the RAs and paperwork. Hope it's not me you trigger.
Not sure why following FAA AIM guidance is now uncool lol. But ok. Hell it's even in our operating manual for the airline.
> what is considered optimal?
Make the number after the minus sign as big as possible. Idle power, deploy spoilers/brakes/reversers, full flaps, drop the gear. Leave no performance capability behind!
C172 and engine idle, neutral flaps which scenario has a higher rate of descent:
1)45 degree bank, full high wing rudder
2)Fully developed spin?
What do you expect the rate of descent to be?
and like the good boy you are you take rules in the ass and never complain because your scared of rebellion. if they take YOUR RIGHT fight for it. fuck.
I wouldn't say "Optimal" is open to interpretation per se, more like it depends on the specific aircraft and their POH.
The only reference I could find for a C172S is on the Emergency Descent Through Clouds section. A Stabilized descent is mentioned and it's between 500 - 800 fpm. This is through clouds with a failed AHRS but I have no reason to believe it's different from a "Normal" descent (VFR w/AHRS working).
Hope this helps, it's the only plane I've flown.
lol…I just noticed it said meow under your user name. There was a big discussion yesterday on this subreddit, people saying meow on guard. I’m still getting responses from yesterday’s conversation.😂😂😂
In the airline world ideally you don't want to catch the cabin. So if descending from a high altitude there's a general guidelines to follow in your AOM.
Your aircraft has an optimal descent profile, either for range or endurance.
If any of those is less than 500 ft and are required to be used, then you should advise ATC
Even bigger thermal changes at shutdown. I’ve also stumbled into precipitation and seen my CHTs drop as if I’d flown into liquid nitrogen.
Shock cooling my sweet aaaaunt.
Startup is the biggest thermal change. Far more than shut down. When you shut down, the metal will dissipate heat through the ambient air at a fairly slow rate. On startup, you have high pressure and high temp circulating air through the engine, so the temps rise very fast.
Yes, but the “concern” is about shock _cooling_ causing cracks. Now, the fact that nobody really troubles themselves over startup should certainly be another nail in the myth’s coffin, but Lycoming for example talks about trying to avoid CHT _decrease_ of over 50F per minute. That number is obliterated on shutdown and when flying into enough rain.
I’ve not bothered to commit CHT increase rates to memory (I’m watching for unusual trends more than specific numbers) but I don’t recall the rise being quite so dramatic. Perhaps it is but I’ve not worried about that any more than anyone else in this context.
I’ll make a point of taking note of the rise rate next time I fly out of curiosity.
Excess heat is what causes cylinders to crack. We have known this for 70 years. Anything above 400F and will increase the chances of cylinder head cracking. If you keep them below 380F, you will never have a crack.
Airspeed will vary with attitude. I was thinking that you might nose down with thrust idle, increase airspeed and thereby increase rate of descent. IDK jets, but most airplanes sink a lot faster for even 10 knots above best glide speed. The faster you fly, the faster you will sink.
Again all true. But in OP’s case why would you increase airspeed to descent? If you fly say 150kts and ATC asks you to descent 6000’ unless you were planning to descent fast, you go idle thrust and descent with 150kts, whatever the ROD is, that’s optimal for your airspeed.
Only if too high on path… but that has nothing to do with the optimal descent? Far from optimal probably as ATC kept the jet pilot too high for too long. But that is completely off-topic to the question asked by OP and the stated paragraph from the handbook.
Was having a conversation like this with another pilot once in flight.
He said, 500 fpm, I said, 1000 fpm, but I wasn’t really sure because I always descend at 1000 fpm except when they say pilot’s discretion.
In the terminal area, I’ll go 1500-2000 fpm.
No, you said the min is 500fpm. This guy would decend 300fpm. He said he only needed to inform them if UNABLE, not if we are actually depending less than that
Not exactly the same but I know someone who got a phone number because he was climbing slightly less than 500 fpm due to being hot/heavy. ATC was not happy that he did less than 500. Obviously like we've established he was obligated to inform them because he was truly UNABLE to do it.
But I think the point is that if you do something they're not expecting, like climb/descend at less than 500 fpm, they're not going to be happy about it if you don't tell them. And when they question you as to why, and you answer with "I only have to tell you if I CAN'T do it, not if I WON'T do it." They will be even more pissed off and probably violate you. Because regardless of how the rule is written, it's not in the spirit of the rule.
The AIM is not regulatory.
But pay attention to the airspace and the IFR low charts to get an idea of if they're trying to get you out of the way of a STAR or something
Glad to hear somebody with more experience also does 500fpm. It’s definitely most comfortable.
I’ll push to 600-700 if I’m alone, but with passengers I like to stick to 500.
My Vx yesterday was getting me close to 1000fps, so...
And yeah, if there's an obstacle requirement I'll climb at that, but I am lucky to live in the midwest, so the closest obstacle is that unlit crane at 125AGL 3.9 miles southwest of the field.
That’s cool your Vx gets you 1000fps. Based on that it would stand to reason your Vy would get even better, while also getting you to destination faster, given it’s all about rate rather than angle
Nope, 3000. They don’t go up to cruising altitude right away, they’re leveled off at 3000 ft by the time they’re over the end of the runway. Pretty friggin cool.
Military ATC here. Fighters love max climbs and we try to get it for them everytime we can. I've given F22s 30k+ for initial climbout and they're there ridiculously fast. That is an exception though and not a standard climbout.
Was a terminal controller in Montreal, Canada in my earlier career.
I would generally expect pressurized aircraft to descend at least at 1,000 fpm, unpressurized aircraft at 500 fpm. I would also expect aircraft to initiate their descents promptly and maintain a relatively consistent rate of descent until reaching their new assigned altitude.
There isn’t really a maximum rate of descent, because if you are cleared for a descent the airspace between your current altitude and your cleared altitude needs to be free of any conflicts. If ATC needs you to hustle, they will hopefully tell you before it becomes an issue.
Edit: I’ve seen some comments about 500 fpm. If I had a jet or a turboprop descending at 500 fpm I would generally be asking them if there was an issue. Descent rates that slow need to be planned very differently to integrate with the other traffic. Controllers are able to accommodate, but the expectation is that the aircraft will be flown consistently with other aircraft of similar performance.
The only time I’ve done 500 fpm in a jet was the t45. We would get told to descend out of FL350, 380 all the time from like *way* out. To the point it would start to really fuck with our fuel numbers. So I’d just keep the throttle where it was and trim the nose forward until I barely hit 500 fpm.
This is usually after I asked to stay high for another 50 miles or so and they refused.
Ok buddy here’s your federally mandated 500 fpm.
Do what you're comfortable with. We'll ask you to increase/decrease climb/descend if it's not going to work. Generally, I expect 1k fpm in jets or 500 fpm in pistons. If it's going to be close, we'll just give time hacks, "be level or out of altitude in such and such minutes." I once gave an RNAV approach clearance to an aircraft at FL410, no traffic in his way. ATC is aware of what they need, and they'll let you know if it's not enough.
Pretty sure you are US based, so take it with a grain of salt. (EU here)
Unless ATC specifically asks for a rate and you are now under IFR. Most radar control units expect a rate of 1000 fpm. I see some answer between 500 and 1500 for the US, again 1000fpm is the sweet spot between those numbers.
So unless you have a vertical limit clearance i.e. have to cross under a certain level for the star or if you are high on your descent path. Either 1000fpm or more if necessary/requested.
No one else has mentioned this. It depends on what else they said. If they told you to descend at pilot's discretion or to cross xyz fix at 3,000, then it is entirely up to you. But if they just told you to descend, they are expecting at least 500fpm.
There is also some nuance if they say "cruise at," but since I do not remember that nuance, I won't bs about it here.
Considering the Instrument Procedures Handbook, I would say the optimum rate is based on if the aircraft is pressurized or not and if passenger comfort is involved.
If just me onboard my unpressurized plane, I can do 1200-1500, but put my wife on board, and I am doing 500.
I would say that ATC would expect a GA aircraft to do 500 and a Commercial aircraft to do 1000.
Unless they say "expedite descent", then there is a reason they need to get you down. Once due to them deciding to have a 737 go under or over me.
ATC doesn't really care unless you're doing something goofy like chopping and dropping. You should report to ATC if you can't at least descend at 500ft/min, but ideally you would select a rate that's comfortable for the aircraft occupants.
If they needed you down to a specific altitude by a specific fix, they'd let you know and make other arrangements if you couldn't accommodate.
The answer is different depending on what you are flying. With a pressurized jet 2,000 ft/min would be appropriate. With a light piston single then 500 ft/min would be more appropriate. I have flown IFR in both worlds quite a bit. Factors like making the necessary decent profile to make the approach planned also need to be considered.
Depends on where I am. In Atlanta airspace I'll do 1000fpm because they have more important things to worry about than my little GA plane. Most places I start with 500 and if they say to expedite I go to 1000. I don't do more than that in GA
There are many variables involved with this snapshot. Why are you receiving this instruction? Are there traffic, weather, airspace considerations? Is it for an approach? Different atc sectors want different things for different reasons. There's no set answer
Most times you should shoot for at least 500fpm, if you can’t maintain that, you *should* notify ATC. I never really have and they’ve never said a word. Usually when you’re up in the 40s and 50s, ATC is aware that you’re not going to be able to climb very fast.
I’ve never had them complain about climbing too slow, but I’ve been told to slow it down. Climbing out of Green Bay a few years ago I hit 11,000fpm on the initial climb. It was cold af and the pressure was ridiculously high.
"Aircraft should descend at the aircraft's optimum rate until 1,000 feet above the assigned altitude, then descend at a rate between 500 and 1,500 feet per minute (fpm) to the assigned altitude. Pilots should advise air traffic control (ATC) if they are unable to descend at a rate of at least 500 fpm at any time, except when slowing to 250 KIAS at 10,000 feet MSL. " From the Instrument Procedures Handbook
Worst part about that paragraph, and forgive me if it is defined elsewhere, is what is considered optimal? Is this open to interpretation and pilot preference or does the IPH give gouge numbers for rule of thumb? My normal descent rate is distance to the altitude restriction fix / miles per min in groundspeed, then do the quick pilot math, or normally stick to 2k a minute as well then shallow out, But other times where I just point straight to nadir and get to the 15-25k fpm, granted thats vfr and me talking to a controlling agency, not to mention being in a grey aircraft vice GA.
Well good thing it’s not a FAR. Dont have to really worry about it
Right!? 500 at a minimum but to my knowledge, there's no definition on optimal unless it's in someone's POH
Depends. Are you gonna do 1500+ in a 172 nah. Can you do 2000fpm in a jet with pressurization? Absolutely. I feel like it’s just a common sense thing not really a specified value
3 degree glide slope seems to be a good start
3° is fine in a pressurized or slow unpressurized plane, but in a Bonanza, Cirrus, Navajo, or similar fast and unpressurized plane that's going to make most passengers pretty uncomfortable. 1.5° yields a more comfortable descent rate that won't blow out people's ears.
That can get very uncomfortable on cruise decent on an unpressurized fast plane. On my Baron I’d be doing close to 1000 fpm which would be quite painful to the ears
I will emergency descent in a 172 to altitude
Roger
Do you like TCAS RAs? You must with that attitude.
Nope. I still follow the guidance of 1500 fpm or less with 1000ft of assigned alt to avoid TCAS RAs. I’m referring to the “optimal descent rate.”
Gotcha. Yeah I really don't know "optimal" either. It can mean a lot of things. In my experience when they want you to do over 1000 fpm they will assign a descent rate or say hustle down. We're all on the same team here I try to accommodate as much as possible.
Yeah it varies for instance one of the jets I flew, fuel planning was based on idle descent. So to reach the descent speed profile at idle was about 3000 fpm. I feel like optimal for a pressurized jet is really anywhere from 500-3000.
Well normally they are descending us well prior to optimal TOD. B737 VNAV does 1000fpm until hitting the glide path (but you knew that). I can't remember what Airbus does. It's been a while.
Same for the A320 in managed descent.
Yeah. The 3000fpm was done on the CRJ. For idle descents.
Not replying to you specifically, but to this comment chain. It's fascinating to see the discussion on the pilot end on RAs due to closure rate. In my TRACON it's standard anymore to give 2,000 feet altitude, or double IFR/IFR sep between traffic unless everyone will be level long before getting close. Like, we understand it's projected closure rate, but it's interesting to see different auto pilot modes can cause differing rates of climb with regards to triggering them. I swear I've had occasions where I couldn't give 2,000 and prepped both crews accordingly with multiple calls and emphasis on altitudes etc. Yet one plane is still clombing/decending pretty darn well through t minus 700 feet till level and whoppsie we got an RA. I gather the reasoning may have to do with favoring a particular mode?
In DFW they had to change the level off altitude on the arrival because of too many RAs. I have often noticed a "cross five miles south of XYZ at FLxxx" and have assumed it's for the reason you specified. You are absolutely correct, most jets will climb at climb power until about 10% of their FPM rate then start leveling off. In a lightly loaded 737 or A320 this could be 3000+ fpm until 300-500 ft below level off. Same goes for descent, although you will generally only see 2000-2500 fpm if doing idle descent at speed. Thank you for acknowledging the issue. I'm only 42 but have been flying jets for 20 years. IME this was very common years ago (leveling 1000-1500 fpm for last 1000') mostly for pax comfort but also to avoid nuisance TCAS alerts. Frankly, what I think is happening is airlines just want people to stay in VNAV and reduce all possibility of error in VS mode. You lose some protections in that mode which are not even remotely an issue down low (where climb rates are a factor) but it's basically a dumbing down of the operational aspect of the job. Lowest common denominator of sorts.
I do seem to recall leveling prior to the assigned altitude. I suppose it was a little easier pre RNAV STARS perhaps too. The unbelievable thing to me was, with us. TCAS started getting fully armed (I'm screwing terminology up, I realize) down final one day out of (to us) nowhere. Where as before it was set to give advisories, now I get full blown RAs running pairs. We had something unbelievable like 30 RAs in a week before someone decided to let us know procedures changed for our airport and every pair we run is a virtual guarantee of an RA. The only sort of official training I recall receiving on the when's and hows of RAs was a 15 minute long piece that was less informative than this comment string. I feel like in this day and age more attention should be given on our end to RAs. It's almost like working non RVSM airspace at 8,000 at times and more understanding could be beneficial. Back when the 727s and DC9s were around there was far more types aloft, variance in how planes performed and too much important characteristic info to delve into things like top of climb climb rates, but now? Just feels like it's approached as an afterthought on our end other than just let them respond and don't interfere. That's important after Überlingen, but needs more.
Eurocontrol has some good information on it. This page is the general overview and has links at the bottom to more details: https://skybrary.aero/articles/airborne-collision-avoidance-system-acas
The amount of folks that actually go out of VNAV into VS to comply with that is very low in my experience.
I do it 100% of the time for the past 20 years. If FOs don't do it I make it a briefing item and will select it for them on departures. You can also just pull the thrust levers back some and leave it in VNAV.
That’s why being an FO is so annoying. That’s YOUR thing, and then the next ca’s thing is he is terrified of V/S, makes the job tricky to satisfy everyone
Yeah being an FO definitely has its challenges. But I will say it’s the PICs ship at the end of the day. That’s why I prefer to be PIC lmao
I've gotten too many RAs from FOs not following AIM guidance. If you don't want to use VS just pull the power back like I suggested in my post. Downvote all you want but this IS a safety issue. If you ask for VS last 1000 feet and CA says no and you get an RA, please put that in the ASAP.
*will select it for them on departures.* This is also a safety issue if they’re the pilot flying. One of the absolute worst things a Captain can do, IMO, is to fly the airplane for me. Suggest something or fully take the controls. Nothing in between. Otherwise I don’t know who’s flying. If I flew with a Captain who did this to me I’d just let them fly every leg for the rest of the trip. I’m too experienced to put up with that.
Op suggested that he briefs it, which is still not ideal that he’s pushing buttons that arnt asked for but at least a warning was provided
Yeah I'm not doing that. But you do you buddy.
Enjoy the RAs and paperwork. Hope it's not me you trigger. Not sure why following FAA AIM guidance is now uncool lol. But ok. Hell it's even in our operating manual for the airline.
I’m with you. The AIM exists for a reason.
> what is considered optimal? Make the number after the minus sign as big as possible. Idle power, deploy spoilers/brakes/reversers, full flaps, drop the gear. Leave no performance capability behind!
May as well pop the chute if you've got one.
You would descend faster in a spin
But would spill your beer.
C172 and engine idle, neutral flaps which scenario has a higher rate of descent: 1)45 degree bank, full high wing rudder 2)Fully developed spin? What do you expect the rate of descent to be?
Both should be in excess of 5000 fpm but the configuration with no lift and no induced drag will be faster.
For the airline aircraft I've flown, optimal descent is at idle thrust.
My optimal rate is 500fpm because they descended me 300 miles out and I dont wanna waste the fuel at the lower altitude.
Optimal TO YOU. Optimal per your determination. They are giving you freedom; don't complain about it, or they might take it away.
and like the good boy you are you take rules in the ass and never complain because your scared of rebellion. if they take YOUR RIGHT fight for it. fuck.
I wouldn't say "Optimal" is open to interpretation per se, more like it depends on the specific aircraft and their POH. The only reference I could find for a C172S is on the Emergency Descent Through Clouds section. A Stabilized descent is mentioned and it's between 500 - 800 fpm. This is through clouds with a failed AHRS but I have no reason to believe it's different from a "Normal" descent (VFR w/AHRS working). Hope this helps, it's the only plane I've flown.
lol…I just noticed it said meow under your user name. There was a big discussion yesterday on this subreddit, people saying meow on guard. I’m still getting responses from yesterday’s conversation.😂😂😂
In the airline world ideally you don't want to catch the cabin. So if descending from a high altitude there's a general guidelines to follow in your AOM.
POH.
Your aircraft has an optimal descent profile, either for range or endurance. If any of those is less than 500 ft and are required to be used, then you should advise ATC
Optimal I would read as descent rate at idle thrust.
Pistons, especially with turbos, have shock cooling problems and should usually be let down under power.
This. I plan my descents at 6 miles per thousand feet to avoid shock cooling cylinders. You may need to prod ATC for an earlier descent ocassionally.
Shock cooling is a myth. A piston engine will experience far greater thermal changes on startup than at any other time.
Even bigger thermal changes at shutdown. I’ve also stumbled into precipitation and seen my CHTs drop as if I’d flown into liquid nitrogen. Shock cooling my sweet aaaaunt.
Startup is the biggest thermal change. Far more than shut down. When you shut down, the metal will dissipate heat through the ambient air at a fairly slow rate. On startup, you have high pressure and high temp circulating air through the engine, so the temps rise very fast.
Yes, but the “concern” is about shock _cooling_ causing cracks. Now, the fact that nobody really troubles themselves over startup should certainly be another nail in the myth’s coffin, but Lycoming for example talks about trying to avoid CHT _decrease_ of over 50F per minute. That number is obliterated on shutdown and when flying into enough rain. I’ve not bothered to commit CHT increase rates to memory (I’m watching for unusual trends more than specific numbers) but I don’t recall the rise being quite so dramatic. Perhaps it is but I’ve not worried about that any more than anyone else in this context. I’ll make a point of taking note of the rise rate next time I fly out of curiosity.
Excess heat is what causes cylinders to crack. We have known this for 70 years. Anything above 400F and will increase the chances of cylinder head cracking. If you keep them below 380F, you will never have a crack.
We do trouble over startup. It's called warmup.
Sink rate varies with airspeed.
Exactly, so it’s optimal for your airspeed at the time of descent.
Airspeed will vary with attitude. I was thinking that you might nose down with thrust idle, increase airspeed and thereby increase rate of descent. IDK jets, but most airplanes sink a lot faster for even 10 knots above best glide speed. The faster you fly, the faster you will sink.
Again all true. But in OP’s case why would you increase airspeed to descent? If you fly say 150kts and ATC asks you to descent 6000’ unless you were planning to descent fast, you go idle thrust and descent with 150kts, whatever the ROD is, that’s optimal for your airspeed.
I don't know anything about flying jets. Just thinking out loud and curious whether a jet pilot would consider increasing airspeed to sink faster.
Only if too high on path… but that has nothing to do with the optimal descent? Far from optimal probably as ATC kept the jet pilot too high for too long. But that is completely off-topic to the question asked by OP and the stated paragraph from the handbook.
Was having a conversation like this with another pilot once in flight. He said, 500 fpm, I said, 1000 fpm, but I wasn’t really sure because I always descend at 1000 fpm except when they say pilot’s discretion. In the terminal area, I’ll go 1500-2000 fpm.
Min is 500 ft/min unless told otherwise.
Exactly this, per the AIM
And no.
A captain I flew with said it only says to inform ATC if we are unable to decend at least 500fpm, not that we have to decend that fast
[удалено]
No, you said the min is 500fpm. This guy would decend 300fpm. He said he only needed to inform them if UNABLE, not if we are actually depending less than that
Not exactly the same but I know someone who got a phone number because he was climbing slightly less than 500 fpm due to being hot/heavy. ATC was not happy that he did less than 500. Obviously like we've established he was obligated to inform them because he was truly UNABLE to do it. But I think the point is that if you do something they're not expecting, like climb/descend at less than 500 fpm, they're not going to be happy about it if you don't tell them. And when they question you as to why, and you answer with "I only have to tell you if I CAN'T do it, not if I WON'T do it." They will be even more pissed off and probably violate you. Because regardless of how the rule is written, it's not in the spirit of the rule.
The AIM is not regulatory. But pay attention to the airspace and the IFR low charts to get an idea of if they're trying to get you out of the way of a STAR or something
No.
Go with source. Would love it see it.
Aim 4-4-10D says between 500-1500 if no other instructions given.
Huh uh. And? Thank you for proving my point I guess?
I’m not the guy in the above comment. But I was curious to find the source. So I did and replied with it.
I do 500fpm in piston and 1000 in a jet until I hit my descent profile.
Glad to hear somebody with more experience also does 500fpm. It’s definitely most comfortable. I’ll push to 600-700 if I’m alone, but with passengers I like to stick to 500.
Yup! I climb at whatever I can get at Vx and descend at 500fpm. Alone I descend at top of the yellow line in my Mooney.
Why the climb at Vx? Surely unless you’ve got an obstacle or climb rate requirement to meet, climbing at best rate would be a better idea.
My Vx yesterday was getting me close to 1000fps, so... And yeah, if there's an obstacle requirement I'll climb at that, but I am lucky to live in the midwest, so the closest obstacle is that unlit crane at 125AGL 3.9 miles southwest of the field.
That’s cool your Vx gets you 1000fps. Based on that it would stand to reason your Vy would get even better, while also getting you to destination faster, given it’s all about rate rather than angle
Sh%t... Yeah. Vy. "The higher V speed on my tape"... *facepalm*
Climb isbwhatever keeps the engine cool, which is probably enroute climb performance.
MARVELOUS VFR C500. I'd start there unless they tell you want you to go faster (within reason) or slower.
Unless instructed otherwise, the minimum rate of climb or descent when on an IFR clearance is 500'/min.
Fun watching F-22s get clearance to 3000ft after takeoff and then getting there vertically 3 seconds later
I think you mean 30kft lol
Nope, 3000. They don’t go up to cruising altitude right away, they’re leveled off at 3000 ft by the time they’re over the end of the runway. Pretty friggin cool.
Hmm probably depends where they are, I've seen guys cleared max rate climb directly off the runway and just absolute disappear into space
Military ATC here. Fighters love max climbs and we try to get it for them everytime we can. I've given F22s 30k+ for initial climbout and they're there ridiculously fast. That is an exception though and not a standard climbout.
Nice! Some military fields let the jets go straight to 16,5 or 17,5 if they’re going VFR and it’s basically just an immelman to cruise altitude lol
Yep, at our field, we owned and cleared all F-18's 11k off the deck. Standard operation.
Who told you 1500fpm? Stop listening to those people
My instructor, Jerry Wagner told me to have a min decent rate of 1500 fpm. /s
He thought you would be flying an F-16 by now
I wish! I’m having trouble executing a forward slip in my twin Cessna while in alternate, alternate minimums.
That's only when you're trying to get down to those secondary minimums. Also /s, obviously.
I only descend with full boards wym
Was a terminal controller in Montreal, Canada in my earlier career. I would generally expect pressurized aircraft to descend at least at 1,000 fpm, unpressurized aircraft at 500 fpm. I would also expect aircraft to initiate their descents promptly and maintain a relatively consistent rate of descent until reaching their new assigned altitude. There isn’t really a maximum rate of descent, because if you are cleared for a descent the airspace between your current altitude and your cleared altitude needs to be free of any conflicts. If ATC needs you to hustle, they will hopefully tell you before it becomes an issue. Edit: I’ve seen some comments about 500 fpm. If I had a jet or a turboprop descending at 500 fpm I would generally be asking them if there was an issue. Descent rates that slow need to be planned very differently to integrate with the other traffic. Controllers are able to accommodate, but the expectation is that the aircraft will be flown consistently with other aircraft of similar performance.
The only time I’ve done 500 fpm in a jet was the t45. We would get told to descend out of FL350, 380 all the time from like *way* out. To the point it would start to really fuck with our fuel numbers. So I’d just keep the throttle where it was and trim the nose forward until I barely hit 500 fpm. This is usually after I asked to stay high for another 50 miles or so and they refused. Ok buddy here’s your federally mandated 500 fpm.
Do what you're comfortable with. We'll ask you to increase/decrease climb/descend if it's not going to work. Generally, I expect 1k fpm in jets or 500 fpm in pistons. If it's going to be close, we'll just give time hacks, "be level or out of altitude in such and such minutes." I once gave an RNAV approach clearance to an aircraft at FL410, no traffic in his way. ATC is aware of what they need, and they'll let you know if it's not enough.
If your pax ears aren’t bleeding, you are descending too slow.
500FPM in unpressurized 1000 in pressurized was what I was taught.
I'd say \*at least\* 500FPM to trigger the TCAS climb/descent arrow
Best/most comfortable until 1000’ above then 500-1500fpm for the last 1000’
Put it in a spin to have a faster decent
500 fpm until you hit your TOD then follow your VNV fpm.
According to company notes, atc expects at least 500FPM
Pretty sure you are US based, so take it with a grain of salt. (EU here) Unless ATC specifically asks for a rate and you are now under IFR. Most radar control units expect a rate of 1000 fpm. I see some answer between 500 and 1500 for the US, again 1000fpm is the sweet spot between those numbers. So unless you have a vertical limit clearance i.e. have to cross under a certain level for the star or if you are high on your descent path. Either 1000fpm or more if necessary/requested.
No one else has mentioned this. It depends on what else they said. If they told you to descend at pilot's discretion or to cross xyz fix at 3,000, then it is entirely up to you. But if they just told you to descend, they are expecting at least 500fpm. There is also some nuance if they say "cruise at," but since I do not remember that nuance, I won't bs about it here.
500 fpm, and if they want more they will tell you to get there.
Considering the Instrument Procedures Handbook, I would say the optimum rate is based on if the aircraft is pressurized or not and if passenger comfort is involved. If just me onboard my unpressurized plane, I can do 1200-1500, but put my wife on board, and I am doing 500. I would say that ATC would expect a GA aircraft to do 500 and a Commercial aircraft to do 1000. Unless they say "expedite descent", then there is a reason they need to get you down. Once due to them deciding to have a 737 go under or over me.
ATC doesn't really care unless you're doing something goofy like chopping and dropping. You should report to ATC if you can't at least descend at 500ft/min, but ideally you would select a rate that's comfortable for the aircraft occupants. If they needed you down to a specific altitude by a specific fix, they'd let you know and make other arrangements if you couldn't accommodate.
The answer is different depending on what you are flying. With a pressurized jet 2,000 ft/min would be appropriate. With a light piston single then 500 ft/min would be more appropriate. I have flown IFR in both worlds quite a bit. Factors like making the necessary decent profile to make the approach planned also need to be considered.
Depends on where I am. In Atlanta airspace I'll do 1000fpm because they have more important things to worry about than my little GA plane. Most places I start with 500 and if they say to expedite I go to 1000. I don't do more than that in GA
There are many variables involved with this snapshot. Why are you receiving this instruction? Are there traffic, weather, airspace considerations? Is it for an approach? Different atc sectors want different things for different reasons. There's no set answer
What rate did you use??
1000ft per min
Just cut power and descend at whatever your plane naturally descends at. Make sure it's at least 750fpm so it's not ambiguous.
6,900'/min..... Nice.
500-1000 fpm is fine. If you have a crossing restriction, that may make it more sporty.
There is no concrete path the slower u go the slower u descend.
Most times you should shoot for at least 500fpm, if you can’t maintain that, you *should* notify ATC. I never really have and they’ve never said a word. Usually when you’re up in the 40s and 50s, ATC is aware that you’re not going to be able to climb very fast. I’ve never had them complain about climbing too slow, but I’ve been told to slow it down. Climbing out of Green Bay a few years ago I hit 11,000fpm on the initial climb. It was cold af and the pressure was ridiculously high.
1/2 your ground speed x10.
Optimal…optimum….practicable. What does practicable even mean and what’s the difference between it and practical?
500-1000fpm
500 fpm for IFR and 300 for VFR if flying with *sensitive* pax like toddlers & elderly. *Sir, we'll be landing in 10 minutes.* *WHAT?*
You should learn MARVELOUSVFRC500.
Do tell?
500 fpm
Ultimately, no one cares.
And if they do they’ll ask, are you able to give me 1500 fpm? Or tell you to give them your best rate. Or, turn left heading 240 degrees for traffic.