REALLY? Large Jets Are Quieter Than Prop Planes?

Is noise a concern to you? Well let's look at the likely impact if Briscoe Field is expanded.

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.

This post is contributed by a community member. The views expressed in this blog are those of the author and do not necessarily reflect those of Patch Media Corporation. Everyone is welcome to submit a post to Patch. If you'd like to post a blog, go here to get started.

Floyd Akridge May 26, 2012 at 06:12 AM
Ken...give it up pal. The truth in this posting is that ESTIMATES were passed off as FACTS simply because the poster, apparently, didn't take the time to actually READ the source documents. 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.
Ken Clark May 26, 2012 at 05:23 PM
OK, now I'm really curious. You analyzed this data. How much scrutiny/fault did you give to Propeller's "study" at their website, which took the same approach (even if for planes that rarely use LZU) and used the same FAA database (although they didn't show the reference for it - wonder why?). Did you you let Brett Smith/Propeller hear about it?? I guess you can't do that when you're the former campaign manager for Mike B who seems to support the expansion at LZU. Beleive me, I've done more than glance at the source documents. I'm glad you finally found 36-3H. I've used it for a LONG time. I also know that AC 36-1H has the measured noise data used for type certification purposes in EPNdB terms. I have worked WITH government employees for a long time. BTW Mike B. is a government employee and, yes, his illogic is astounding. If you're going to discount data because it's from the government source, that's your prerogative, I suppose. 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.
Floyd Akridge May 26, 2012 at 11:47 PM
Ken...as I said in my previous post, it's apparent that you've at least skimmed through the circular..probably more. That's fine...as a data analyst I appreciate that. But it disturbs me that you don't understand what I posted. I didn't say I had analyzed the data in the circular...in fact, I said I hadn't. Not sure how you missed that. 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.
Tim Sullivan May 28, 2012 at 04:39 PM
OK I think we can all agree that both sides’ presents data in a manner that best shows their point. I personally don't care who "picked" the planes for comparison, but I find it strange that we're only comparing 40% of the current usage. • 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.
Ken Clark May 28, 2012 at 09:53 PM
Tim, 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.


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