CRJ-200 Climb profiles
 

(Also posted on another forum)
I know there are quite a few -200 pilots on here. I was bored on some long flights over the last few weeks and started going through performance numbers and the possible fuel savings with different climbs/cruise/decent speeds as well as cruise altitudes. I am wondering what other carriers have as a "best burn" climb/cruise/decent profile.

Here is our "published" climbs:

Best Climb 250/.70M
Normal 290/.74M
High Speed 320/.77M

I was "experimenting" or maybe better to say "interpolating" with climb rates with slight variations to these climbs and found that using 270/.70M kept us at 700-1Kfpm all the way up and saved a couple hundred pounds of fuel and only cost us a couple mins of time. 280/.70 wasn't much difference in fuel but didn't change the time. The problem I have with the 290/.70M climb is the plane just dies after about FL250 trying to hold 290. At about FL250 you will indicate roughly .70M so you could climb at that speed and still be well above the 250IAS limitation for a climb and maintain more than 500fpm up. Trying to climb at 250IAS all the way up seems to have 2 big problems- 1) ATC will hate you and 2) Through FL180 at 250 the plane is a dog!

As far as cruise I have been looking at winds and such and many times we are legal and able to go up 2K and many times 4K feet with a lower fuel burn and many times the winds aren't much different and we even go faster. This is something that all pilots look at (well most), but my issue is why does dispatch/the company not look at this in the planning process. It does seem to work out better to level off at FL280 (an example for original filed ALT), pick up some speed, then continue up to FL320.

Decents for us are typically 290IAS and we have the Vnav set at 3.0degrees. Fiddling with 3.5degrees kept us higher for a little longer and still gave us the ability to slow to 250 for ATC (of they need us to) but we decend with a much lower power setting and save some fuel.

I have been going through various flights and charts and find that just a few changes will (many times) reduce burns by 300-500lbs on a 2 hour flight. At $110+/barrel gas I am curious why others haven't really started looking at burn numbers. You are talking about $100/hr savings which isn't huge, except when you look at the big picture- thats Alot of $$$..


Now I am fully aware the company published numbers probably came from Bombardier and I am sure there are many engineers and lots of science behind all the numbers, but many times the book says one thing and reality is another- we all remember the GA days of a Cessna that should climb but really won't! I am really just curious what other carriers do for the climb mainly. Also curious what people do on the ground (APU and single engine taxi procedures).
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You'll be getting a new book from Delta in the next few months. It has the best fuel saving numbers for a given weight, Alt and temp.

Comair has the top secret PPAS. Basically a book with the most optimum numbers for our old aircraft. Generally 290kias until we reach the cruise mach which could be anything from .65 to .74 depending on weight, temp, and wind and then we'll climb at that mach until cruise then that could be as fast as 0.8 with a strong headwind. Also during the climb if we need to get higher or maintain a certain climb rate it allows us to fly really slow. 250 is the min without the book but with the book it is much slower. It also has a section for descent.

Yea.... let the good times begin...

A very interesting topic indeed. However, I only have one little problem with your numbers.... Our limitation calls for a min climb speed of 250KIAS to the point where it marries .70M. That only occurs at roughly FL320.

So for all our tight captains that seem to see you climb at 250 and .67M at some odd level (say.... 290...) and then get all antsy and tell you to speed up to .70 because that's what our book says.... NEWSFLASH!

That only occurs at FL320 and only on the longer flights the mach becomes a limiter for our climb speeds.

I too experimented and got to where I used IAS 290 until the climb rate dropped below 1000fpm, then climbed in VS mode at 1000fpm to cruise altitude. Normally the IAS would be around 260-270 when you leveled off if you were going FL300-340, and I never saw lower than 250kts. I found it got you to altitude in a reasonable amount of time and still with enough airspeed on the wing to allow acceleration to .74M or higher under all conditions (well, without cowls anyway).

I usually try to fly what our training "Guru" wants us to fly - 290 until .70 and then .70. In "Climb" mode. Yeah, it sucks maintaining 290 and a decent rate above about FL220, but by FL250 you have .70 and then follow that up and the climb rate is actually not bad. Besides, if you climb like that you usually have some reserve indicated speed in case ATC asks you to expidite.

I don't know about that one... What alt will you indicate (roughly) .74M and 290IAS... about FL280. I was up at FL340 and FL360 this past week and we were just below the 250IAS but we were doing well above .70M. I never was below 250IAS or .70M in the climb up to FL360 although our initial level off was FL300 and we let it accelerate before climbing and climbed at 500fpm for a healthy margin above .70. I will keep looking but keep in mind mach transition is actually different depending on temp and the aircraft (at least how I understand it). The CRJ transitions at 31,600 where our planning is FL280 and higher a .74M cruise. I may be wrong and this is the point of discussion so keep the comments coming. I am debating on making a formal proposal to Flight Standards about this. This would be fun to deal with in addition to the new checklists... yea we are getting another checklist revision (a few actually). I personally like the changes...


I also have no problem bringing out documentation to prove a CA wrong. Safety is first but keep in mind many of the crusty guys only flew tprops before the RJ. I have flown with some guys who want to stay low just so they have a "margin". I am not condoning anyone go outside the aircraft's operation envelope, yet utilizing the aircraft to max efficiency should not be a topic of contention. I will do some more research myself but the RJ does have a large operation envelope. I just wish it had another 1000lbs of thrust per side and fadec. I guess I will need to fly the -900....

actually it isn't the "tight ass CA's" fault. It is usually training dept. Any CA who has been here a few years will tell you some of our procedures/systems knowlegde have changed about 6 times since we got the RJ, its kinda hard sometimes to keep up with all those.

"married" is not a word used in the CFM. The word is "transition to." Therein lies the problem. At what altitude do we transition to mach? F280. Therefore, with the way our CFM/training dept. has worked in the past, this can be interpreted as min of .70 when transitioning to mach at F280. However, several chapters later it does say in plain english, 250 or .7, whichever is less.
In addition, if the CA want you to fly faster for better margins, that's his perogative, so long as you're not bustin a limitation. He's the head honch, big cheese, numero uno...
Lots of new FO's have no respect for the slow speed performance/deep stall characteristics of this aircraft. I'd rather see 15 knots fast on a sloppy approach than 5 knots slow and no effort to correct. Or flying at .7 instead of 250 in the climb because you cant look up every few seconds from you USA today...

"As far as cruise I have been looking at winds and such and many times we are legal and able to go up 2K and many times 4K feet with a lower fuel burn and many times the winds aren't much different and we even go faster. This is something that all pilots look at (well most), but my issue is why does dispatch/the company not look at this in the planning process. "


2 reasons. Our SOC has always been stuck in the saab era, even tho we havent had them in 6 years. Hence going to MEM-HSV at 14000 when you could easily do mid 20's and burn less fuel and get your true airspeed up.
reason 2...they give you whatever the computer spits out, with no human thought process involved.

W-R-O-N-G! To say that we transition to mach at FL280 is a wrong simisism!

There's a reason FL280 is such a known number and that is because 290KIAS at temperatures close to ISA equals to .74M !

It's not a company standard or anything like that , that we "transition to mach" at FL280.... that's training department bs.

Therefore my friend, the word married is not misplaced at all. And therefore, it is my personal (you can interpret that as technique if you so will) belief that while using a 250/.70 profile, we only "transition to mach" at FL320 on days where temperatures are close to ISA.

I hope this helps clarifying things. I have no problem if numero uno wants something different, but don't quote me some bs statements that have nothing to do with reality. If you feel more comfortable with an extra 5 knots then say so, it's that simple.

This has little to do with CRJs, but be wary when focusing solely on fuel savings.

Just to put another coal in the fire.... Where did 31,600 come from for the -200 changeover to mach and half-bank. I have my answer that I looked up during initial and had to go outside the company books... What is your reasoning for using FL320?

wow someone got defensive. Do we not cruise at a mach number at F280 and above? yes. You push the center of the airspeed knob to bug mach. hence "transition" in the eyes of some pilots. I guarantee I have about 5000 more hours at this company and have dealt with more training here than you, so to say my statements were BS is totally assinine. Plus if you had read my post, I agreed with you and was stating why some CA's might not see it that way. jeez.

Why all this talk about hard altitudes? Mach changes with temperature...which is never the same any two days. Therefore, usually, you will transition from 250/.70 at FL320, but not always...

Schone...
After reading your post again, were your "BS comments" directed at me and my post, or the CA's you have flown with who did not give you a reason for what they were doing? or both? cause if they were directed at me, I can see why your CA's dont explain stuff to you. Since you tried to rip me a new one for explaining to you how some other CA's think, yet you dont want a "because I'm the Captain" answer.....seems like one cancels the other out...

If I misread your post and it was directed at those CA's you have flown with that don't explain things, I apologize if my remarks came off as "too aggressive." Since we all know communication is only 10% verbal I'm sure you can see why i thought it was directed at me...

Mooney's comments are not bs statements and actually have a lot to do with reality. Most jets transition from IAS to Mach at FL280 which make it a good benchmark. The goal of training is to standardize procedures and a good standard for transitioning from IAS to Mach is FL280. Yes, we all know there are times when you may have to use IAS above 280 but as a general guideline and standard, FL280 works. By the way, I hope your day gets better.......

I believe 31,600ft is 10,000 meters. Good old Canada. Not sure why it has to be 10,000 other than it's a nice round (metric) number.

Mooney: Yes, mostly the BS statements were towards CAs that need to reinvent the wheel. And primarily towards our training dept and how they teach things.

If I came off aggressive then my apologies too.

As for the topic at hand. We press the IAS/MACH bug button at FL280 because most usually for temperatures that are close to ISA, the point where 290IAS equals .74M is at FL280. It just happens to be that way, and since we climb at 290 and transition to .74 when the two marry each other to the TOC that's why there's this notion that it's a company thing to always transition from IAS to MACH at FL280. While in fact, the company just says climb at 290/.74 (or 250/.70 or 320/.7something that i don't remember) and doesnt specify where or when to press that button except in order to meet 290/.74 profile. I guess i'm nit picking about the wording...

As for reasons from captains. I have no problem what so ever with CA saying something to the effect of, i am more comfortable with X let's do it that way. No questions asked there, we know who is in charge and who'se name is on the line. But I have a major pet peve (read dislike) for people that tell me do it this way because it says it in the book, when clearly our books state something different... that to me is reinventing the wheel, micromanaging and doing it with sheer ignorance.

higney:

FL320 is an arbitary number, it is by no means a scientific altitude that predicates guarenteed transition at all. All I mentioned is, that our books call for a slow climb at 250/.70 and that these two usually marry eachother at *around* FL320.... do not get hanged on this number.

As for your question FL316.... I honestly do not know a good answer. If you have one, please share. If I had to venture/guess, I would think it had to do with two things. 1) An arbitary altitude that signifies where the high altitudes start on high weights, warm temperatures days and finer A/P functions are needed to avoid upset of the small buffet margins.
2) Again, a GUESS. They prolly demonstrated good fuel numbers on a 250/.70 climbs and for some average tempreture they determined FL316 to be the point where you transition from one to the other. All in order to demonstrate good fuel numbers on the sheets.... just like they based every performance number on 25%MAC.

All guesses.

so yeah all that sounds good. :)

actually i do it the way higney said. i will climb at 290 till it hits .70. then i will just press the center of the speed bug and put it at a climb of .70. sure the mach moves down as we go higher, but you will keep a fairly constant 700-1000ftpm climb as you do it all the way to cruise. it works great and keeps you from having to just put 500vs in and watch your plane lose all of its energy. ah but alas the "energy" discussion is a different topic!

i just throw 2 cans of Red Bull in the fuel tanks and she clims like a GV.

Ok everyone, I agree with the whole 250/0.70 whichever is less in the climb. However take a look at our FOQA parameters:

The FOQA Monitoring Team looks at a variety of events such as the following:
• Excessive Taxi Thrust (>41% N1 Dual Engine / >51% N1 Single Engine)
• Climb Speeds < 250 Knots above 10,000 feet and < Mach .70 above FL280• High Descent Rates (> -5000 feet per minute at all altitudes / > -3000 feet per minute during approach)
• Flap Overspeeds
• Flaps < 45 degrees / Thrust Reversers not armed / Gear not down by 1000 feet on approach
• Vref deviation at threshold / High or Low landing speeds
• Hard Landings (> 1.45G)
• Excessive Reverse Thrust (>30% N1 below 60 knots for > 8 seconds)



What is up with that?

The transition Altitude is understood to be FL280 by the company and the training dept. While we can argue up and down the company profile is 290/.74M. That happens around FL280 with a standard altimeter and around standard ISA. While Isa -5 or +20 does create a difference in true transition point to Mach, its normally still close enough to FL280 to use this as a standard.

One thing we all need to understand here is we are using this "transition" point in a multitude of ways. Technically in the US we use FL180 to transition to 29.92". I believe there are many other parts of the world where the trans point is different and hence the ability to change the transition point easily within the FMS. Mach transition is different per airplane and per environment (temp). FL316 trans to half bank and Mach is ICAO I believe to deal with both the Meters and the understood ICAO point at which everyone will be reporting in Mach and FL. I have not studied nor flown international (beyond Canada) so I may be wrong, but that is what I understood when I looked it up in initial.