That's right.... that's a BIG LOAD! The show this week is all about weight, balance, and proper loading of your airplane.
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00:01
Behing the Prop
Clear prop S73 Cherokee number two following twin traffic three mile final Bravo Makesford in Runway two five going four mile.
00:10
Nick Alan
This is behind the prop with United Flight Systems owner and licensed pilot Bobby Doss and his co host, major airline captain and designated pilot examiner Wally Mulhern. Now let's go behind the prop.
00:23
Bobby Doss
What's up Wally?
00:25
Wally Mulhern
Hey Bobby, how are you?
00:27
Bobby Doss
I am fantastic as always. This is going to be a very good show with a very interesting title. Today's show is called that's a Big Load and Wally is a dp hears a lot of things on checkrides that make him scratch his head. I hear a lot of things around the fly school that make me scratch my head. And today we're going to be talking about loading an aircraft. We're going to talk about the quick conversation about weight and balance. We've done shows on that before, but we want to talk about weight and balance briefly. We're going to talk about the CG and aft and forward cg, what might better kind of how the airlines do it, how you should be thinking about doing it even in a small single engine aircraft.
01:15
Bobby Doss
And then we're going to talk about kind of where people go wrong on checkrides, what they should be prepared to discuss and maybe little bit more from our show two weeks ago about where they could find some valuable information that might help them manage their big loads. Wally, you are almost a third away around the world right now as we record the show. Do you worry about the way you load your aircraft before you take 300 plus people to Hawaii?
01:47
Wally Mulhern
Yes and no. Personally in within the airlines we have a whole department of our airline that manages loading the airplane and it makes life easy for us. And we call that person our load planner. And they're the ones who figure out okay, we have a triple seven. We were book two to 336 people today we expect to have some extra people. So we're going to fill it up. We're going to fill every seat. We have this much cargo we have, you know, we know by the how the people have checked in, we know how many checked bags we have. So we have a very good indication of what the weight of the airplane is. Now that load planner then passes that information over to our dispatcher who then plugs those numbers in and is able to flight plan for us.
02:56
Wally Mulhern
In other words, we want to cross the ocean at the most economical altitude. Well, we may be too heavy to get up to 38,000ft so we may need to be down at 36 or 37 or something like that. So it's all, you know, it's different pieces to the puzzle of planning a flight.
03:23
Bobby Doss
Aren't there averages like, don't you take my weight? Or isn't there a. If there's 300 souls on board, aren't they just using an average? I bet that average is a little less than my weight.
03:34
Wally Mulhern
They are, they are. And quite frankly, I know that the average keeps changing back in my commuter days, we had average weights, we had summer weights and winter weights. In the winter you were five pounds heavier than you were in the summer. And so we did that. And I want to say each bag was, I want to say this is a long time ago. I'm going back into 1986. I want to say a checked bag was 34 pounds on average. Now I know today, you know, when you check your bags, they weigh it. So I think those numbers are the real numbers.
04:19
Bobby Doss
Oh, okay. I think, I don't say it's probably 55, average of 55 pounds because people are probably holding up on them a little bit when they put them on those scales.
04:28
Wally Mulhern
Right, right. So, you know, the heavier the airplane is, the more fuel we're going to burn. It takes more energy to propel a, you know, a 550,000 pound airplane through the air than it does to propel a 450,000 pound airplane. So all these things come into play. And so luckily, as major airline pilots, we don't really deal with that. Now tonight, when I fly back from Hawaii, I will call our dispatcher, you know, about two hours before the flight and I'll get a briefing over the phone. And probably the first thing that he. Because at this point I will have already looked at the flight plan digitally and I will see what we're planned for. So, and it, at this point, we have a projected payload. We're projecting to have a payload of whatever. And payload is just what it says.
05:33
Wally Mulhern
It's, it's the load that pays the bills. So it's the weight of the passengers and the bags and the freight. Okay, that's the payload.
05:43
Bobby Doss
That's a big payload.
05:45
Wally Mulhern
Yeah, yeah. So probably the first thing in the conversation he'll tell me is he'll check in with the load planner and he'll come back and he'll say our payload is down £3,000 from what were projecting. Now when they, you know, create the flight plans, they probably overestimate the payload. And by and large, most of the time the actual payload is actually lower than what we originally thought. Thought, and that's a good thing. If the payload ends up, you know, maybe there's a, another airline that cancels. All of a sudden we get another 30 people that weren't expecting at the last minute. We'll, we will probably get a new flight plan. And you know, maybe the altitudes are going to change, maybe the altitude will stay the same, but our burn, our fuel burn is probably going to go up.
06:51
Wally Mulhern
So now we're landing on the other end with less fuel. So if were supposed to land with, you know, an hour, 45 minutes worth of fuel, now we may be landing with an hour, 40 minutes worth of fuel. So, you know, it's, it's a complex equation that, you know, a lot of that stuff we don't really factor in small airplanes. You know, we come up with a fuel burn. We say, hey, in cruise we're going to burn 8.2 gallons per hour. And you know, that's whether we're at our max weight or, you know, two, three hundred pounds below our max weight. It's not as big a difference. But when you're talking about 20, 30, 40,000 pounds, it does make a big difference.
07:37
Bobby Doss
I would think so.
07:38
Wally Mulhern
And also over, you know, over an eight hour flight, it's going to make, you know, you take that large weight difference and then compound it by eight hours and it may make a big difference.
07:53
Bobby Doss
Is fuel real important to a big jet as much as it is to a little Cessna?
08:00
Wally Mulhern
Same concept. Same concept. Zero fuel, zero thrust. Yeah, it's one of the top five things that we need to be concerned with. I think number one was fuel. Number two, I think was fuel. Let's see, three. I'm looking at my list here. Three, fuel. Four, fuel. Five. Fuel. Okay. Yeah, there you go. Top five things.
08:24
Bobby Doss
Well, the number six might be weight and balance. But, but do you think of weight and balance as one thing or two things?
08:32
Wally Mulhern
Yeah, this is, you know, when I talk to young people about being pilots, a lot of them look at me and they say, do I need to know math? And I look back at them and I say yes. And I don't. You know, my gosh, our, as a society, I think our math skills are just, they're not good. They're not good. And I was always pretty good with math growing up and it was just part of life, Matt. I, I didn't own a calculator until high school. I think and at that point, they were crazy expensive. But anyway, weight and balance is. Is 2. When I was a active CFI, I would teach it as two separate equations, two separate things we got to worry about.
09:36
Wally Mulhern
We have to worry about the weight aspect of things, and then if the weight is acceptable, then we have to worry about the balance. Now, no question about it, the balance gets a little more complicated than just the weight portion. The weight portion is nothing more than addition and subtraction. You know, you look at an airplane and you're going to have an empty weight of the airplane, and that's going to be somewhere in the poh. You're going to, you know, what is my empty weight of the airplane? Okay, it's. It's X. Well, what is the max takeoff weight of the airplane? Well, it's Y. Okay? So the difference in those two numbers is our useful load. That's how much stuff. Fuel, people, bags. That's how much stuff we can put on the airplane. I, you know, I've got a Saratoga.
10:36
Wally Mulhern
I think most of you know that the useful load of my Saratoga is 1358 pounds. Okay? And, you know, it's just a number I've committed to memory. And, you know, if someone comes up to me and says, hey, why don't you me so and so and so and so fly up to Indianapolis next weekend and watch the Texans play. Play the Colts, you know, and I'm right there, and I'm looking at the five other people that they mentioned, and I'm thinking, well, okay, these are all big guys. We're all 200 pounds. That's 1200 pounds right there. That leaves me 158 pounds of fuel. It's not going to work.
11:25
Bobby Doss
Lots of stop. Lots of stops.
11:27
Wally Mulhern
Yeah, it's just not going to work. Now, if they come up and they said, hey, how about you, me and so the three of us, how about we go over to New Orleans to see the Texans play the Saints? I go, well, okay, now we're talking. Now I'm doing the math in my head. Okay? Here's three guys together. We weigh maybe 700 pounds. That gives me another 658 pounds. My airplane holds 102 gallons. So, you know, even with full fuel, that's 612 pounds of fuel. Okay, that's very feasible. I used to have a 172. And I always thought this was cool because the 172 had a 777 pound useful load. And you know, I always knew that I'm probably never going to fly that airplane more than about three hours. Figure 30 gallons. 30 times 6.
12:39
Wally Mulhern
777 minus 180 is in the neighborhood of 600. It's actually 597, but let's call it 600. So, you know, if I got three people and the average weight is all less than 200, we can probably make this work. So I'm doing the weight and balance. I'm doing the weight portion in my head before I'm even putting pencil to paper. And in these days, maybe entering it in foreflight. I, I do, I checkrides. I get a lot of, well, foreflight says we can do it. Well, okay. You know, there's old saying called garbage in, garbage out. The problem with foreflight is when you're entering your weight and balance information in there's a lot of data points that you have to put in there. And if you get something wrong, it's going to be, you know, your answer is going to be wrong.
13:38
Wally Mulhern
So, you know, getting back to the weight and balance, I mean, just work out the weight portion first. Okay. The, you know, I have a useful load of 200 or 600. 600 pounds. And I got two people that weigh 180 apiece. Well, 180 times two, that's 360. 360 from 600 is 240. 240 divided by six. That's how much fuel you can take. And it's actually pretty simple because if you're above that weight limit, you can't go. You got to do something. Either you're going to have to take out fuel bags or people. Something is going to have to give. So I, you know, I used to tell my students, do the weight portion first. Do the weight portion first. If the weight works out, then do the balance portion and see if we're within the envelope.
14:47
Bobby Doss
And so we talked. Let's talk about that now. So, you know, we're talking about the center of gravity. Where is it going to lie in that envelope? And I think there's a lot of discussion, normally not well thought through or knowledge about this, but forward CG versus aft cg, what's going to benefit the plane, the fuel consumption, the comfort, the pilot skills of being able to fly the plane. Let's talk through all those, if you would. Let's start with. We start with your plane and your load and Your flight for eight hours in fuel. You know, if I'm flying a Cessna 172 from Houston to Austin and I'm taking my wife and some bags, does it, Matt, does it really matter to me where. Where I plan that cg?
15:40
Wally Mulhern
Yeah, well, it does.
15:41
Bobby Doss
I mean, and do I have any control over it? I guess, like, yeah, I don't have a load master.
15:47
Wally Mulhern
Right, right. You know, you. You have some minor controls over it. You know, you. You have the control of. Do we put the bags in the back seat or do we put them in the baggage compartment? That's really.
16:01
Bobby Doss
I was thinking about my wife there in that situation. I was actually going to put her in the back seat. Maybe the baggage.
16:06
Wally Mulhern
Yeah, you. You could put your passenger in the back seat. I, you know, like. Like my Saratoga. I know that two big guys in the front seat with full fuel are. We're going to be out of cg. It's going to be too far forward. Now what I do have is I have some ballast. So what I can do is I can throw some weight in the aft baggage compartment, and that will maybe let the two big guys ride in the front seat. As long as we're. We throw the extra weight in the back. So we may be adding weight to get in balance. And that's. That's kind of something that we might think is kind of weird. Wow. We're adding weight, you know, but that might be what. What is needed. But, you know, weight and balance is.
17:05
Wally Mulhern
Is in general, I think we all think, oh, we don't want an aft cg. The airplane is less stable with an aft cg. True statement. However, is it still stable enough? Is the question. You know, and so now we get into the risk analysis. If we wanted to guarantee that we're not in an airplane crash on a given day, the only way we can do that is to not fly. So we're. We are accepting a risk by the fact that we're getting in an airplane. I mean, that's the cold, hard truth.
17:43
Bobby Doss
Yep.
17:44
Wally Mulhern
It may sound kind of brutal to say that, but that is the fact. I mean, I. I'm sitting here. I went down to the lobby of my hotel and I bought a cup of coffee. I'm taking a risk by drinking this cup of coffee. I don't. I don't know what's in here. I think it's got some water and coffee, and I put some sugar and cream in. It tastes pretty good, but I'm taking a risk. So in general, we think we want a forward CG. So, you know, one thing that comes up on checkrides is I will give the applicant a scenario where we are overweight and out of balance and they have to kind of troubleshoot and figure out ways to fix it.
18:34
Wally Mulhern
And then I will say, okay, well, at the end of the day, let's say we are able to get the CG right here and I make the dot as high up as we can go on the chart and as aft as we can go on the chart. And you know, we're in the box, we are in the envelope. And I think word has gotten out in Houston, Texas that's what Wally's going to do. And, and now people are a little bit more inclined to say that they would accept that scenario and go ahead and make the flight. Now, if you as the pilot say, no, I don't want the CG that far back. Well, that's your prerogative. But then I do ask if there are any advantages to an aft cg.
19:27
Wally Mulhern
And this is where the water gets a little muddy with the responses because this is where some people kind of struggle. And the fact is there is an advantage to an afcg and that's a better cruise performance, better cruise speed. You're going faster for the same amount of fuel burn. So basically your miles per gallon has just gone up. And we all know if you've listened this enough, we know that one reason that a lot of airplanes crash is because of fuel problems. And the main fuel problem is a lack of fuel. So if we're going on a long flight and we can save some fuel, well, maybe we got more fuel at the other end. Maybe we don't run out of fuel, and maybe that FCG helps with that. I will tell you this.
20:27
Wally Mulhern
You know, the airliners, where do you think the airlines try to put the cg? They try to put it pretty far aft.
20:40
Bobby Doss
Well, that makes sense, right? You said payload. We're talking about paying what the. Yeah, I, I'm sure the airlines have a lot of expenses, but one of those biggest expenses has to be fuel. You're flying eight hours, £500,000. That's going to be a lot of fuel. A dang straight. They're going to put it FCG in there. And I don't think. When I was really flying to Austin, I thought about it, but man, in the 182 with three of us, it probably makes the most sense to put the heavier person in the back that can't fly the plane probably makes sense to put the bags in the baggage compartment and not in the back seat, which is probably a bad habit of all of us. We have better access to it, so we put it in the back seat.
21:23
Bobby Doss
But that can make a huge difference. You know, if I was running low on fuel, I sure wish I had those three or four gallons for sure.
21:30
Wally Mulhern
Yeah, yeah. I, What I try to do is I, I, I do put, you know, in my Saratoga, I put my stuff. Well, I mean, I, I run the weight and balance. I do have a forward baggage compartment that I can use, and that's where. That's where I put the light stuff. You know, I have a cover for the airplane, so when we get to wherever we're going, I can cover it up if we're going to be there for, you know, more than a couple of days. And, you know, it's. It's a canvas cover, so it's not that heavy. So that. That lives in the nose compartment. So I, you know, try to put my, you know, the light stuff goes up front.
22:08
Bobby Doss
So what. What's the downside to having an fcg? Is there a downside to the fcg? Is there something that I should be worried about if I. Yeah. Was too aft?
22:19
Wally Mulhern
Yeah. Well, it is. It is less stable. Okay. Less stable. And we hear that and we kind of freak out and we go, oh, my gosh, less stable. We're gonna. We're gonna crash and die. I think we could make the argument that driving down the road at 10 miles an hour is safer than driving at 50 miles an hour. Okay. If I hit something at 10 miles an hour, probably not going to do a whole lot of damage to me. It may damage the car at 50 miles an hour. Maybe. Maybe it's going to damage me. So I think we could make the argument that, you know, 10 miles an hour is safer than 50 miles an hour. It's. But is 50 miles an hour. Do we consider that unacceptably unsafe?
23:16
Wally Mulhern
And I think most of us would say no, we don't consider that unacceptably unsafe. So it's. It's kind of that way with an aft cg. I mean. Yeah. Is the airplane a little bit less stable? Are you going to notice it? Probably not. And, you know, were talking earlier about the stability of a 172 or a warrior. I mean, they are freaking stable airplanes. I mean, when all else fails, if you're in trouble, probably just let go of everything, and the airplane will probably get pretty close to where it needs to be on its own. That's how stable they are. But yeah, it is less stable. Still stable enough, but less stable.
24:02
Bobby Doss
Well, I'm sure there's a number of, maybe experimental or even just GA aircraft out there in general that aren't as stable as a Piper Warrior or a Cessna 172. And that might make a difference. I, I haven't yet flown one of those that would be unstable, but I've heard of things that are a little less stable, a little less forgiving. And maybe that's where you wouldn't want to be as aft CG in that situation.
24:29
Wally Mulhern
Yeah, I think so. I think you could probably talk about fighter jets, maybe aerobatic airplanes that have a much smaller envelope.
24:41
Bobby Doss
Yep. Where do people go wrong with all this stuff? We talk, we're talking weight and balance, which is really the CG and the balance part. We talk about the board and a half conversations on a checkride. I don't know exactly where, how far you get into all that. And then useful load. We've talked about max gross weight a bunch. What, what are some of the, we'll call them common errors on checkrides, Wally. That the listeners need to be prepared for.
25:10
Wally Mulhern
The common errors are either arithmetic errors, just simple math. They can't say 170 +70 is 240. And they, you know, I'll, I might give a scenario where they're 24 pounds overweight and I ask how much fuel we could take off and to get within limits. And I would say 85% of my applicants pull out a calculator to go 24 divided by 6. And maybe. God, maybe I'm just showing my age by thinking, are we at a place where people don't know that 24 divided by 6 is 4? And that's. I don't know. I, I guess if we always have a calculator in our hip pocket, that's one thing. But I just kind of feel like we oughta, we ought to know that the second area of concern is just always trusting foreflight.
26:24
Wally Mulhern
Now, I think foreflight does an excellent job, but going back to what we said earlier, if you don't get those data points in there exactly right on your airplane, your envelope is going to be crazy. I can't tell you how many friends I've talked to over the phone when they'll send me a picture of what their weight and balance envelope on their airplane looks like when they put everything in foreflight. And it's just crazy. So, you know, and to their credit, they say to me, something's not right here. What, what am I doing wrong? And we are usually able to work it out. But you know, that envelope that you create in foreflight ought to look very much like the envelope in the poh of the airplane.
27:11
Wally Mulhern
And if it doesn't, you need to, you know, you need to kind of reevaluate because again, garbage in, garbage out. If you're putting bad information in the foreflight and it's, it ha. It doesn't know the, you know, the correct data points, the correct numbers, it can't calculate a good CG for you.
27:35
Bobby Doss
Yeah. Do you think it's, I mean, math is a problem? I, I was gonna joke about our show a couple weeks ago where we talked about looking stuff up. It'd be nice if I could just bring Suri with me and ask her a bunch of questions and get the answers from her. She came on my iPad there to the left of me as were talking because she was gonna answer my questions. But what do you think it's really the book knowledge? Do you think it is the lack of knowing where to look stuff up or is it simply math skills that caused the applicant the most trouble?
28:11
Wally Mulhern
Math skills always come into play. They, it rears its ugly head a lot. And, and I think another problem that we have is that we are used to flying these four place trainers for the most part, whether it be 172s or Piper Archers or Warriors. And yeah, two people, two average sized people in that airplane with full fuel. I, I don't know, 98% of the time you're going to be just fine. So I think we're in the habit of just not doing the weight and balance. I, I would venture to say if, when I, I, in fact, this is something I think I'll throw in here to my private pilot applicants is to just ask them, how many times have you actually done a weight and balance?
29:14
Wally Mulhern
They, they probably did one early on in their training or their instructor showed them how to do it. They probably reviewed one before their check ride and I, I would say a lot of them maybe have only done it two times.
29:29
Bobby Doss
And I'll say this, I probably got sucked in that trap for a long time. I did my flight review recently as you know, and my instructor said, did you do a weight and balance? And I had to fess up and say no. I said I can do one. Happy to show you my skills. Right I was thinking it was more of a, are you capable still? This is a flight review. I need to see that you can do a weight and balance. And he's like, no, it's not about that. It's like, if you don't do it every time, what are you gonna do the time that you're out of weight and balance? Like, you're not gonna know it, right? So you need to do it every time.
30:04
Bobby Doss
He said, I'd much rather have done one this today and tell the NTSB or the FAA that I did do one beforehand instead of telling them, hey, let me go figure it out after the fact, right? He goes, I just would never want to be ramp checked and not have a weight and balance that I did for that particular flight. And he said, really, how hard is it? If you got the profile in foreflight, you really only need to ask me what my weight is and that's it and you should do it every time. And I thought, wow, that's, that is impressive. You are right, I am wrong. And I think I'll do a weight and balance every time I fly a plane. Moving forward, because his logic is accurate, I should do one every time.
30:46
Bobby Doss
And for those students out there that think that's just a waste when it's the same plane and the same instructor, I challenge you. Dipstick those tanks. See if your bag really weighs what you think it weighs on a scale. Make sure you're doing a weight balance every time. And then come checkride day, it's going to be a lot easier to face. Wally on the checkride day, obviously every.
31:08
Wally Mulhern
Major airline that takes off the weight and balance has been done and it is documented. When I used to fly charter back in the day, part 135, again, this is in the 80s. I don't, I don't know if the rules are still the same, but you know, we, I would fly some people from point A to point B and then point B back to point A. And in my flight bag I kept, I had to keep weight and balance sheets I had to keep, I kept self addressed, stamped envelopes to my company I worked for. Because if the weight and balance changed, in other words, I took off with full fuel. We got down there and realized we didn't need to get fuel or, you know, something changed, that the weight and balance was different from what I had planned.
32:03
Wally Mulhern
I had to fill out a new weight and balance sheet and it had to physically be mailed back to my company. And that was all for accident investigation. God forbid something happened and we went down, they would be able to get the most accurate weight and balance. So the FAA wants to see that. And it's, you know, it's important. It really is.
32:25
Bobby Doss
Wally, you know that 90% of the people listening are wondering why you just didn't take a picture of that and text it to your company?
32:35
Wally Mulhern
Yeah, well, I'm sure that's what they do now. And, well, in foreflight, you know, as we're saying all this, I thought, gee, I wonder if there's a function in foreflight where I can take the weight and balance and email it to somebody. I'm sure there probably is. I've never got it. I've never. Yeah. Yeah.
32:52
Bobby Doss
Well, I'll give everybody one last tip. If you are going to take a check ride with Wally, I must tell you, work on your mouth skills a little bit. I've been around Wally for many years now and he does. I thought I was really good at math. Occasionally he spits out some of those numbers while ago and I'm thinking I did not keep up with that. So work on your math skills a little bit. If you're going to see Wall E, make sure you understand the loading of an aircraft. Know what you're going to do with your big load, and no matter what, stay behind the prop.
33:21
Nick Alan
Thanks for checking out the behind the Prop podcast. Be sure to click subscribe and check us out online@brave.theprop.com behind the prop is recorded in Houston, Texas. Creator and host is Bobby Doss. Co host is Wally Mulhern. The show is for entertainment purposes only and is not meant to replace actual flight instruction. Thanks for listening and remember, fly safe.