schone

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.

labbats

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

higney85

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?

mooney

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.

ExperimentalAB

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...

mooney

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...

RickJames

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.......

Speedbird172

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.

schone

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.

Airsupport

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!