Okay you want to know how I know this, right?
Well, Better Gwinnett has been fortunate to have the support of a very intelligent, real live rocket scientist. In his current position, he is exposed to FAA and aircraft data on a daily basis and knows how to obtain and analyze independent data available from the FAA.
If you look at the two linked charts you will see that the Cessna 172 and Cirrus SR 22 single engine prop aircraft, a Beech Baron 58 twin-engine prop, and a Beech Jet are 4 commonly used aircraft operating at Briscoe.
Notice that the Cessna 172 and Cirrus SR22 aircraft are about 15 - 20 decibels quieter than the Beech Baron 58 and Beech Jet. Propeller aircraft using LZU are anywhere from mid-50s decibels on approach to the upper 70s decibels range. You will also see that the Beech Jet produces approximately the same noise volume as the passenger jets projected to operate at Briscoe, and that the loudest jet, a 737-700, is 25 decibels louder than a Cessna 172.
You will also see that the noise “footprint” for a 737-700 is 16-miles long and almost one-mile wide, while the “footprint” for the Beech Baron 58 prop aircraft, is only 8-miles long and approximately one-half mile wide.
Well if you live in the fantasy world in which Brett Smith (Propeller Investments), Mike Royal and Paula Hastings (both Fly Gwinnett Forward) live, that would be correct. Of course, if you live in the real world like most people in Gwinnett County then you won’t be surprised to find out large jets are louder than the prop aircraft which currently use Briscoe.
As I stated the person that performed the study is an aeronautical engineer, spend a career with Rockwell Collins, and currently works in the avionics field. I think him eminently qualified to perform this analysis. I don't mind you asking questions, that just adds confidence to the data we present. But let's hear your educational background so readers can decide who they want to believe. Are you an engineer? What is your aviation background? Do you work with FAA data as part of your daily job?
http://www.whyprivatizebriscoe.com/questions.php The Beechcraft Baron 58 is the most common user of LZU by far. And it's one of the noisier (not the noisiest) planes using LZU. Propeller likes to cite LJ24s, GIIs, and C206s that hardly ever use LZU. The FAA noise data is the FAA noise data. So, if you want to blame anyone for the comparisons - blame Brett Smith.
The simple truth here is that your comparisions are asinine. I even used the multi-engine plane (the baron) instead of the single engine 172. The truth here is not the db's actually numerical value but **YOUR** comparision of aircraft that even the kid down the street would laugh at.
You've grasped the concept, dishonest representation, but you're attempting to blame me instead of Fly Gwinnett Forward. Why is that? Use your superior intellect to prove to us how Fly Gwinnett Forward is correct that a Cessna 172 is louder that a 737?
Why am I mentioning you? You are the one making the comparison in this post...sorry I thought you knew. Furthermore, I was trying to be nice about this and give you the opportunity to notice it yourself but your study gives no data, that I saw at least, at what range these db ratings were taken. That matters and could actually matter quite a bit. For instance...was it taken standing at a safe distance from the aircraft? That's a tad irrelevant since no one is housed on a taxiway. What I would find more relevant is what is the db rating of each aircraft at say 1/4-1/2 mile from the runway. Since sound energy decreases with the square of the distance we may actually find that a 172 is actually louder than the 737 at a measurement that really is relevant. Don't know that for certain though but give the 737's much better Vy ratio it's at least plausable.
Once again we are comparing the aircraft that actually use Briscoe, rather than picking out the loudest models to skew the data and results, as Fly Gwinnett Forward did. If we were trying to manipulate the data we might have chosen a 747, because they are loud. But I suspect the runway length at Briscoe is too short for a 747.
Floydie is just mad that you and the rest of the citizens panel used your heads and came to the conclusion that so many others have concluded: Briscoe should not be commercialized. He consistenly points the finger at you for the facts listed because you and the other good and intelligent people shot down the golden parachute that Mike B probably offered him for his past support.
So, if the analysis presented here which considers 3 prop and 1 jet aircraft for LZU now (which, BTW, is pretty representative of the mix of traffic @ LZU) and 4 jets that Brett Smith lists at his website for "anticipated" aircraft at LZU is asinine, then what does that make Propeller's "study" that lists 3 jets (which hardly ever use LZU)and one prop for current aircraft + the same "anticipated" aircraft? BTW, good thing you weren't an English tutor. Is a "calculus tudor" a style of architecture?
This is not analysis...it's a bar graph that presents a slice of data without specifying any of the conditions used. I've explained that in previous posts. It's possible, depending on the test that the 737 could be worse than what is posted in the bar graph. The truth of the matter is that we don't know. Hence why I've hammered on the comparison used in this post as some sort of reliable proof.
You were asking about how the noise data presented here was generated. Did you need the full set of atmospheric parameters (e.g. precipitation, relative humidity, dry bulb temperature, dew point, absorption coefficients, and wind velocity)? What about the steady approach speed, Vref, approach configuration, and maximum landing weight? How about recording equipment specification for the sound calibrator, windscreen, microphone system, signal recording and conditioning devices, and one-third octave band analysis system? Or what about the sound incidence angle, reference direction, free-field sensitivity, and calibration check frequency parameters? Or did you just need… the “range”?
But not to worry...I did your leg work for you. Here's something interesting in the circular...on the first page Item 4. "However, it should be specifically noted that the reported levels are estimates and do not represent actual certificated values." **WHOOPS** you mean your facts are actually ESTIMATES according to the source YOU QUOTE? Dang man...you should read stuff like this BEFORE you post. Btw...they do inform the reader about where they measure. Interestingly enough...it's about where I suggested but that was just an educated guess on my part. I guess my education was good enough after all wasn't it? http://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentID/22945
With respect to the things you mentioned HAD YOU READ THE CIRCULAR you would have seen how many aircraft were listed and would, hopefully, have an understanding that it would be scientifically, mathematically and physically impossible to maintain a perfectly consistent test environment. I accept minor inconsistencies in the testing environment for the obvious reason. Read the advisory circular...it's interesting. I've provided the link above...
Golden parachute? You make me laugh...hard. You are both funny and very sad at the same time. I think it's a personal statement on you that you can't think in the terms that perhaps someone would volunteer in a campaign simply because they thought the candidate was the best person. I'm glad I'm not in your world...it's WAY too small for me. You need to get out more.
2000 meters.
Another thing...don't wave the FAA flag in front of me. Have you ever worked as a government employee? The amount of illogic that circulates through every agency is monstrous and the FAA is no exception. Finally...the 2000 meters shows that you at least glanced at the source documents and I'll give you credit for being the only one besides me who apparently has done so. However, it's not just 2000 meters...I haven't gone over the dBA numbers yet because that wasn't the question I wanted to answer but they also do a number on takeoffs....after a 6500 foot roll. Ken...you can stand there and accuse me of trying to "pick it apart" but I am a data analyst. My question on measurement locations was an analytical and scientific solid question given how sound energy dissipates. The real story here is that the poster tried this back door insult to my education and it turns out that they apparently didn't read the source documents. BTW...look at the dBA ratings for the gulfstream IV...those are some quiet aircraft.
As far as the Gulfstream IV goes, if it used LZU more than rarely I might care. But it doesn't. I'll stick with the C172, which does use LZU and is MUCH quieter than the G-IV.
I am responding to THIS post Ken. That should be painfully obvious by now. It's the unsuccessful tactic of your side of this issue to throw any flak in the air in hopes that some of it hits. This is a PRIME example. The poster, OBVIOUSLY, did not read (know of?...dunno) the source documents. Can you and I agree that was simply sloppy work? What's funny is that I wasn't even looking to tear apart the source. Having a decent understanding of sound energy, I was curious how the dBA was measured...a scientifically and analytically sound question. The circular basically answered that. With respect to Commissioner Beaudreau, I'll take him over any of the other candidates in this race hands down. You can gulp down data because it's from a government source...that's your prerogative. Given the FAA's history as well as how calculations are made in other areas...such as the commerce and labor departments statistics, that's problematic imho. Not that it's always wrong...just needs extra A-1 sauce to get it down.
• What makes up the other 60%? Is it 40 different kinds of planes? • Are none of the 60% similar enough to be grouped together and added to the chart? • If noise is the issue then should we not discuss All of the current traffic and it’s makeup and noise level? I’ve done some door knocking in Lawrenceville and on occasion heard some very loud planes landing. Wonder what these planes were? The folks I talked to always seemed to call them Lear jets, perhaps just a familiar name, or maybe they were Lear's. Let’s compare them in real time, let’s pick a spot 2,000 meters away where the noise is the highest and actually record the current traffic landing and taking off. Let’s have the propeller guys land a couple of the Jets they propose to service Briscoe and do some take offs and landings and record that as well. It seems like the proof is in the pudding and not in charts and stats that each side can shoot down, just saying. This is an important decision, let’s all try and act like Adults about this.
I would say the data presented here by C4BG is very reasonable. Check out the last 2 weeks of arrivals at LZU at www.flightaware.com and you’ll see that the 4 current aircraft C4BG identified accounted for 37% of the arrivals. That’s pretty close to 40%. Of course, that % fluctuates over time. You’d also see that jets only accounted for 18% percent of the arrivals at LZU over the last 2 weeks. Again, showing 1 out 4 flights as being jets is pretty reasonable for LZU. There are probably 60+ types of aircraft that have used LZU over the last 2 weeks, but there are a lot of those 60+ types that hardly use LZU - just as you speculated. So, what about Propeller’s noise study? Here it is… http://www.ahkfoundation.org/questions.php The “current” aircraft they identify (G II, LJ24, Global Express & C206) account for only about 1% (not a typo) of the flights at LZU (based on the most recent 2 weeks at LZU). So, that’s not representative - at all. LZU has far more propeller operations than jet operations. Propeller’s mix ratio (3/4 jets at LZU) isn’t even close to reality. As far as the dBA data they show goes – well, they are extremely selective. For example, for the LJ24D they show 80.6 dBA, but there is another LJ24D that is only 77.8 dBA. For the 737-700 they show 65.8 dBA – even though FAA 36-3H shows that the 737-700 ranges from 65.6 to 77.1 dBA, with an average of 71.6 dBA, based on over 100 737-700 data points.