mesa...lets go for a ride

[dooork]

Ok, just to debate you a little on the whole "fatal accident" metric for being a bad airline I ask you to read this NTSB report: http://www.ntsb.gov/ntsb/brief.asp?ev_id=20011030X02159&key=1

Now, it was from 6 years ago and I also recognize that Mesa operates thousands of safe flights since then. But you don't have to have a fatal accident to make you raise your eyebrow and wonder if others operate in the same manner.

And after saying that I will acknowledge that other airlines have also had such incidents that make you raise your eyebrow. http://www.ntsb.gov/ntsb/brief.asp?ev_id=20071217X01939&key=1

Ridiculous. It is one thing to have a dummy do something like this....it is another to have a trend....thats what we are talking about.

 

[Dubya]

What's the real story about MESA? Their CLT base is very appealing and they are union.

PM if you like...It's very difficult to get the real story on here.

-

They suck.


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This just in. Breaking news from our National Dooshbag Taskforce Bureau (NDTB).

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[AvroJockey]

what's mach trim do?

Automatically and gradually trims the tail-plane on transonic aircraft to adjust for the rearward change in center of pressure as a result of wing shocks at higher mach. Mach trim is more commonly found on swept-wing aircraft as they are more susceptible to rearward changes in CP because shockwaves start at the thicker wing root.

I think the 737 starts mach trimming at .615...someone correct me if my memory sucks.

It doesn't do anything for any abrupt shock stall and tuck though.

 

[AvroJockey]

Can't speak for the Excel or the CRJ/ERJ, but at FL450 and mid-cruise weight (11.5k) the CJ2+ is at the 1.3G reference line when at the Mmo of .737.

I'd think as long as one is at or above that 1.3G reference on the buffet charts, the aircraft should be able to withstand a sudden bout of moderate turbulence without experiencing a mach-induced upset.

I think you're right...1.3G chart is what I've used in the past, and I think it's pretty cool some avionics are starting to correct for this. The Excel doesn't, and at max weight (at takeoff), when at FL450 you can only go to .70 or .72 if I remember correctly (Mmo is .75).

 

[keri2000]

I've never flown the CRJ but every jet has buffet boundary charts which give you the low and high speed buffet boundary for weight, flight level, and g loading.

I would believe that the CRJ has a relatively large margin between high and low speed buffet at it max certified flight level (FL410, I believe) and weight, most transport category aircraft do. However, that doesn't mean you can go to .85 in all flight conditions. Anyone that flies a jet needs to pull out the AFM and take a look at these charts to get an idea what the general limits are, otherwise you're putting lives in danger.

Believe me, this is a real threat. We had a crew on the CE560XL with your mentality (beeper goes off at .75) and they were introduced to mach stall when they hit a little turbulence. Luckily no one was hurt.

BTW...every avionics suite that i've flown fails to accurately correct for high speed buffet boundary limits, so I wouldn't trust your beeper!

True. And at lower altitudes the hi speed buffet is almost always .85. At higher altitudes there isn't enough power to get close to that. Plus the 700 and I believe the 900 have an RVSM speed limit of .83 anyways.
Somehow I doubt the original poster was thumbing through their speed card to know if they where approaching any said buffet boundary so in the CRJ if it's not beeping at you their is a good chance you are not exceeding any.

 

[d.fitz]

When you feel the high altitude rolling motion and see airspeed close to max you do tend to get concerned

So, in an airplane you know nothing about, you "felt" a rolling motion and then noticed they were near Mmo and that led you to feel in danger?

I think there is a LARGE difference between a lear 35 based on a swiss fighter jet (which means minimal stability, for maximum maneuverability) and a modern day glass cockpit airliner designed to FAR part 23.

I'm not a fan of MESA as a company, but I am a fan of all my friends that are gracious enough to give me a ride... You should be too...

 

[stagger]

d.fitz

I never said I felt like I was in danger. Those are your words not mine. But I do know the feeling of high alt buffett. I have felt the buffett many times on purpose at high altitude in a previous job. In this case the f/o said to the capt. "What was that" and the capt said "just some chop". I very politely said it might have been something called mach buffett and thats when I pulled out an old flip chart of mine from my bag to show them what I was talking about. Simple as that

 

[DrewBlows]

d.fitz

I never said I felt like I was in danger. Those are your words not mine. But I do know the feeling of high alt buffett. I have felt the buffett many times on purpose at high altitude in a previous job. In this case the f/o said to the capt. "What was that" and the capt said "just some chop". I very politely said it might have been something called mach buffett and thats when I pulled out an old flip chart of mine from my bag to show them what I was talking about. Simple as that

What airplane, what altitude, and what speed. Perhaps if you provide details someone who has actually flown the airplane can verify your concern.

In my opinion it would be hard to notice a buffett with the high speed warning chirping in your ear. I'm certainly no expert in aerodynamics but the good people at Embraer and Bombardier are and I suspect they set limits at levels that won't cause a couple of over-exuberant pilots to soil the good name of their companies.

 

[~~~^~~~]

Stagger - can you provide some numbers? Altitude, Mach, Temp? What was the weather, where were they at? Just curious.

 

[viper548]

during certification the aircraft is required to fly at .07M above MMO. The CRJ is certified at .85, so it has been flown at .92, that does not make it OK to exceed any limitations. You just wont fall out of the sky if you momentarily exceed it.

 

[AvroJockey]

during certification the aircraft is required to fly at .07M above MMO. The CRJ is certified at .85, so it has been flown at .92, that does not make it OK to exceed any limitations. You just wont fall out of the sky if you momentarily exceed it.

Is this in smooth air though?

They design 1.3G Buffet boundary charts so there is margin in case you encounter unexpected turbulence.

The limit is not always Mmo (though it is for 95% of flights). You should be using 1.3G figures for some margin when you're high and heavy.

 

[AvroJockey]

I'm certainly no expert in aerodynamics but the good people at Embraer and Bombardier are and I suspect they set limits at levels that won't cause a couple of over-exuberant pilots to soil the good name of their companies.

Remember they're trying to sell airplanes too! When they make buffet boundary charts they assume pilots will use them.

 

[viper548]

Is this in smooth air though?

They design 1.3G Buffet boundary charts so there is margin in case you encounter unexpected turbulence.

The limit is not always Mmo (though it is for 95% of flights). You should be using 1.3G figures for some margin when you're high and heavy.

I don't know if it's done in smooth air but I would suspect so. Do any airlines use buffet boundary charts for the CRJ series? At skywest we don't.

 

[DrewBlows]

I don't know if it's done in smooth air but I would suspect so. Do any airlines use buffet boundary charts for the CRJ series? At skywest we don't.

You have some sort of chart that shows you the maximum altitude for a given weight. I think I read that you guys do some sort of fuel savings program, I'm guessing it gives you a maximum altitude?

 

[viper548]

You have some sort of chart that shows you the maximum altitude for a given weight. I think I read that you guys do some sort of fuel savings program, I'm guessing it gives you a maximum altitude?

We have a climb capability chart that gives us a maximum altitude for a given weight and temperature in with the speed cards