Usable weight consistantly not followed?

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Maverick3n1

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Maverick3n1
I'm new to flying, and have my student license and am cleared to solo, but I have not yet taken the written or hands on test (I excelled at my hands on and can pass the hands on test no problem, but fell behind on my studies of the manual for the written).

That said, I have asked my instructor numerous times and never truly got a straight answer from him. I consistently see people flying in scenarios where based on the airplane's rating, they are flying overweight. For example, two full grown men, weighting 200-250 lbs each, getting into a CZAW Piper Sport that has a useable weight of 450-480lbs. With their weight alone, there is no room for fuel, yet they hop on in, full tank of fuel, and don't appear to have any issues climbing.

I've seen 3 full grown men get into a C172 that was just topped off by the local fuel supplier, take off and fly without a problem, and being that it's the primary type of plane I fly, I know the older models are typically around 800 lbs of usefull load (1960-1980 C172). The 3 men plus the full tank has to put them in the 900's. They appear to climb at around 500fpm however...

Are the planes listed weight, under-rated compared to what they can actually safely carry, or perhaps those weight restrictions have not so much to do with ability to climb, and more so with the ability to take sharp turns at 45 degree+ turns. Obviously, with my instructor being in his role, these kinds of topics are taboo, and the only answer he will give me is to "fly under max weight".

I'm a creature of understanding. If someone tells me that the plane's top altitude is 12,000 feet, I want to know why. Not because I want to try to go above 12,000 feet, but I want to know what stops it from being able to do it safely. The same is the case for this. Flying is obviously very dangerous if you start pushing the limits of the aircraft beyond spec, but I want to understand what sets the max weight limit to what it is, yet why I consistently see people breaking these weight limits at the airport with much success. They only seem to be breaking the weight limit by 10-15% for the most part, with maybe the exception to the CZAW, with such a low limit, they are breaking the limit more by like 25-30%. What's the deal?
 
Some folks fly overgross, it ain't right, but I'd mind my own.
 
Maverick3n1 said:
I'm new to flying, and have my student license and am cleared to solo, but I have not yet taken the written or hands on test (I excelled at my hands on and can pass the hands on test no problem, but fell behind on my studies of the manual for the written).

That said, I have asked my instructor numerous times and never truly got a straight answer from him. I consistently see people flying in scenarios where based on the airplane's rating, they are flying overweight. For example, two full grown men, weighting 200-250 lbs each, getting into a CZAW Piper Sport that has a useable weight of 450-480lbs. With their weight alone, there is no room for fuel, yet they hop on in, full tank of fuel, and don't appear to have any issues climbing.

I've seen 3 full grown men get into a C172 that was just topped off by the local fuel supplier, take off and fly without a problem, and being that it's the primary type of plane I fly, I know the older models are typically around 800 lbs of usefull load (1960-1980 C172). The 3 men plus the full tank has to put them in the 900's. They appear to climb at around 500fpm however...

Are the planes listed weight, under-rated compared to what they can actually safely carry, or perhaps those weight restrictions have not so much to do with ability to climb, and more so with the ability to take sharp turns at 45 degree+ turns. Obviously, with my instructor being in his role, these kinds of topics are taboo, and the only answer he will give me is to "fly under max weight".

I'm a creature of understanding. If someone tells me that the plane's top altitude is 12,000 feet, I want to know why. Not because I want to try to go above 12,000 feet, but I want to know what stops it from being able to do it safely. The same is the case for this. Flying is obviously very dangerous if you start pushing the limits of the aircraft beyond spec, but I want to understand what sets the max weight limit to what it is, yet why I consistently see people breaking these weight limits at the airport with much success. They only seem to be breaking the weight limit by 10-15% for the most part, with maybe the exception to the CZAW, with such a low limit, they are breaking the limit more by like 25-30%. What's the deal?
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The deal is, those guys just need to run out of runway one time and they will regret the overload. Or hit a downdraft and then the ground...
 
Thank you, Skywag. I've wanted to join the club since I was a little kid. Finally having the means (sorta) to do it is awesome!

James, I see it very consistently. It's like saying "You shouldn't go faster than the speed limit on the freeway" and realizing that only about 10% of the vehicles on the freeway are going 65mph or slower in a 65 zone. Going 75mph instead of 65 on the freeway, is no more or less safe outside of the fact that if you are in an accident, the accident has more potential to do more damage. The speed limit isn't a limitation of the vehicle, but a limitation of the public's ability to drive said vehicle safely at those speeds.

In aviation, the opposite seems to be in play. The numbers for limits on an aircraft have everything to do with the airplane's limitations, and nothing to do with the pilot's limitations.

So I ask again. Why does it seem to be something where people commonly break these limits, yet they are listed as though if you break them, you exceed the limitation of the plane and will probably crash? I understand the concept of being so overweight that you are lucky if you get into ground effects, but as you try to climb out of ground effects, you start sinking and crash. This isn't the effect I'm seeing from the people doing this however. They are taking off just fine, in most occasions, not even taking up a huge amount of runway, and they are climbing at 400-500fpm, so I don't understand why the strict weight limit.
 
CTLSi, if I go 100 lbs over the rated max weight of the aircraft, but can still climb at the expected 500 fpm, I'd have to be in some serious downdrafts to not be able to keep up with it, and if I'm in downdrafts so bad that 500fpm with 100 lbs overloaded isn't enough to climb out of it, then I probably wouldn't have much luck being 100lbs under max load either, and probably shouldn't have been flying in that weather condition to begin with...
 
I think I may have answered my own question about the CZAW's at least. It appears that there is a limitation put on light sports at 1320 lbs gross, regardless of how the plane is built. So in reality, that plane could truly only physically support 1320 lbs total, or it could have been built so it's base weight was 1300 lbs, and structurally overkill, but could carry an additional 1000 lb load. Regardless, US limitations say 1320, so that's what's written in the manual. That explains the ability to fly with two 250lb people and a full tank of fuel, yet still be able to climb without a problem.

Now how about the Cesna? Are there similar limitations on those planes based on classification, or are their numbers more accurate?
 
Maverick3n1 said:
CTLSi, if I go 100 lbs over the rated max weight of the aircraft, but can still climb at the expected 500 fpm, I'd have to be in some serious downdrafts to not be able to keep up with it, and if I'm in downdrafts so bad that 500fpm with 100 lbs overloaded isn't enough to climb out of it, then I probably wouldn't have much luck being 100lbs under max load either, and probably shouldn't have been flying in that weather condition to begin with...
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You know that overloading will increase stall speed, and change W&B. It also has a direct effect on ground roll (dependent also on density altitude), and screws with load factors in various types of turbulence.

You might get away with it most of the time, but you are pushing past the envelope and increasing risk.

The manufacturers publish a weight max for a reason. So why screw with it?
 
Here's a fun fact: the Cessna Skymaster that I fly has a max gross takeoff weight of 4,200 lbs. The military version used in Vietnam as a FAC had a max takeoff somewhere near 5,400 lbs. Were substantial airframe improvements made to increase the weight? No.

Am I going to try to takeoff 1,000 pounds over gross? No.
 
Every airplane is weight limited based on the aerodynamics, mostly of the wing. The more wing area, the more weight that can be supported. For example, let's take a generic C172 - the wing specs are: Wing span 35ft 10in, 26ft 11in so the wing area is 175 sq ft. Assume max weight of 2200 pounds, this gives a wing loading ratio of 2200/175 or 12.6 pounds per square foot. The wing load on a 747 is 152 pounds/sq ft of wing. Why is this important? Because the faster an aircraft flies, the more lift is produced by each sq ft of wing area. The downside, is the higher the wing loading, the less maneuverable. This is why you hear the term "unload the wing" to reduce the angle of attack.

So, assume we put those big guys in the 172, and the weight is now 2600 with full fuel and all the luggage. The airplane needs almost 15 pounds/sq ft to fly but only has 12.6.

Of course there's tolerances built in, but do you want to be a test pilot?

Want more? Go take an aerodynamics course.
 
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Overloading can be one of two things: an overweight condition or an out-of-balance condition.

If the plane is overweight, it will suffer from reduced performance, lower useable g loadings, and may unsafely load the structure. How much overloading is a problem depends on the plane, load, environment, etc... Apropos of nothing, if you see a Skyhawk overloaded 20# or so and call the FSDO they'll most likely just yawn at you.

If a plane is overweight or loaded so that it is out of balance- Bad Things Happen. For a too-forward CG, you can run out of elevator authority on takeoff or landing. For a too-aft CG, you may not be able to keep the nose down after liftoff. Do Not load out of CG.
 
Maverick3n1 said:
I think I may have answered my own question about the CZAW's at least. It appears that there is a limitation put on light sports at 1320 lbs gross, regardless of how the plane is built. So in reality, that plane could truly only physically support 1320 lbs total, or it could have been built so it's base weight was 1300 lbs, and structurally overkill, but could carry an additional 1000 lb load. Regardless, US limitations say 1320, so that's what's written in the manual. That explains the ability to fly with two 250lb people and a full tank of fuel, yet still be able to climb without a problem.

Now how about the Cesna? Are there similar limitations on those planes based on classification, or are their numbers more accurate?
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Every aircraft and variation has specifics defined and published. It's called the TCDS Type Certificate Data Sheet. You can find one for any airplane (other than the experimentals) at the FAA website. Here's the one for C172:

http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/724e90061c5bf3b1862576260063e599/$FILE/3A12.pdf
 
Limitations are based on the airplane as a whole. Landing gear, rudder travel, flap design, etc. We routinely see gross weight increases in planes that only require minor modifications, sometimes none at all. Lift is proportional to the square of airspeed times the area of the wing. So for a given airfoil for a doubling of airspeed you get a quadrupling of lift. This increases the wingloading but as long as lift exceeds gravitational force the plane will fly.

But the POH has to be written to reflect these changes including stall speed and rotation.

Landing gear is rated to take high loads, if you were to land well every time no problem. But if you stall 8 feet off the runway and are overweight the landing gear may fail.

Realize even the limits we have are made up, why must landing gear withstand say 10G impact, why not 5g or 15g. 5g would be less weight but 15g would be safer for rough landings.

It's a balance of factors, made up or statistical factors. But someone made the decision of what the limitation should be, but that doesn't necussarily mean the plane isn't capable, and no matter what the limitation is set to, the plane can be overstressed given the right conditions.
 
Higher wing loading makes it less maneuverable? More BS to call out.
 
Paulie said:
Higher wing loading makes it less maneuverable? More BS to call out.
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I agree. I haven't heard of this.

I have heard that the more stable the aircraft it, the less maneuverable it is, and vice versa. It's why fighter jets of today are flown by computers.
 
Got that right. Less stability more maneuverable, computers needed to fly.
That comment he made was cut and pasted off Wikipedia. A great source of BS.
 
Paulie said:
Higher wing loading makes it less maneuverable? More BS to call out.
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I won't go into the equations in "Aerodynamics for Naval Aviators" but remember the load vs airspeed graph you learned about in private ground school? Oh look, it's even in color to represent the white, yellow, green & red markings on the airspeed indicator.

figure3.gif


Higher wing loading means slower turn speed (manueverability) because you need more lift to overcome induced drag OR more speed to deal with the parasitic drag. Stall speed increases either way. Take-off & landing performance is also reduced. Power-on stalls anyone?

References: Kershner, "Advanced Pilot's Flight Manual".

Like these better than wikipedia?
 
So the answers I've gotten so far, in summary, equate to "The number is made up, and who's to say what the wing of the aircraft can actually handle, as well as landing gear?", "More weight/wingload = less maneuverability", "Military can make the exact same aircraft, carry 1000 lbs more than it's rated for, by merely classifying it as military", and "CG is what matters."

Of those, I agree with the CF matters. That's a fairly simplistic understanding, especially for someone who's flown remote control airplanes and helicopters prior to going for his pilot's license. That said, the weight thing is still a trip to me. I can understand the military considering it acceptable to add more weight to a C172. When it comes to war, more risk is sometimes worth the reward. If I were to fly a C172 on a bombing mission where I dropped some big payload off the bottom of the aircraft, they wouldn't care so much about my maneuverability, over whether or not I could get off the ground and over the target to drop it.

It still goes to point out that nobody has truly given a real solid answer to why the numbers are the way they are, and yet they seem to be skewed between what the recommendations are and what people actually follow. Especially in the case of the Light Sports, where some random number was placed to call an aircraft "light sport" whether or not it could do more. They aren't looking at structural capability. They are looking at classification requirements for their rules, as if I recall correctly, a light sports pilot does not require as much training as a private pilot.
 
Paulie said:
Higher wing loading makes it less maneuverable? More BS to call out.
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Actually that is true. For any given wing, the higher the loading the less maneuverable the plane.

Generally more maneuverable planes will have a high wing loading, but that maneuverability is due to thinner airfoil profiles and smaller wings relative to the rest of the plane- not the high wing loading. Otherwise fighters and bombers loaded down with munitions and fuel would be more maneuverable than their clean-wing counterparts.
 
Maverick3n1 said:
So the answers I've gotten so far, in summary, equate to "The number is made up, and who's to say what the wing of the aircraft can actually handle, as well as landing gear?", "More weight/wingload = less maneuverability", "Military can make the exact same aircraft, carry 1000 lbs more than it's rated for, by merely classifying it as military", and "CG is what matters."

Of those, I agree with the CF matters. That's a fairly simplistic understanding, especially for someone who's flown remote control airplanes and helicopters prior to going for his pilot's license. That said, the weight thing is still a trip to me. I can understand the military considering it acceptable to add more weight to a C172. When it comes to war, more risk is sometimes worth the reward. If I were to fly a C172 on a bombing mission where I dropped some big payload off the bottom of the aircraft, they wouldn't care so much about my maneuverability, over whether or not I could get off the ground and over the target to drop it.

It still goes to point out that nobody has truly given a real solid answer to why the numbers are the way they are, and yet they seem to be skewed between what the recommendations are and what people actually follow. Especially in the case of the Light Sports, where some random number was placed to call an aircraft "light sport" whether or not it could do more. They aren't looking at structural capability. They are looking at classification requirements for their rules, as if I recall correctly, a light sports pilot does not require as much training as a private pilot.
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If you want the answer try reading a book instead of being a lazy bastard and looking for answers here and then crying when you aren't satisfied.
 
There are some 172Ns with a useful load over 1000 lbs.

Basically, put a 180HP engine in it and limit flap to 30 deg.

They are quite a lot more capable than even the later 180 HP 172s (those are fat pigs) and can rather easily hold three adults and full fuel. Legally, as long as you have the STC.

It's not easy to identify these by sight. You need the W&B paperwork.

The big risk for overloading is not maneuverability or reduced climb. It's inability to climb out of ground effect at all. Particularly on a hot day.
 
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Paulie said:
If you want the answer try reading a book instead of being a lazy bastard and looking for answers here and then crying when you aren't satisfied.
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Another thoughful answer.
 
Maverick3n1 said:
It still goes to point out that nobody has truly given a real solid answer to why the numbers are the way they are
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You're asking a question that doesn't have a single answer. Nobody here can point to one specific factor and say "this is what all max gross weights are based off of", because there are many factors that aircraft engineers have to consider when setting the limits.

At any certain weight, the ability to maintain a positive climb rate at full power does not mean it will pass the many other specifications and flight tests that have to be demonstrated for certification. Any one of the hundreds of specifications can be the one that puts a cap on the max gross weight.
 
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If you reach 12,001 is the plane gonna stall? No.
If the useful load is 800 and you load it to 801 is the plane gonna crash? no.

During pilot training I knew a student that accidentally flew an entire sortie with the flaps down. Over speeding them by over 50 knots. Yeah the plane had to be inspected and yes he got an ***reaming from the instructor, but they didn't fall out of the sky.

Lets face it, if everyone followed the rules to the tee...There would be a lot less Cessna 152s and similar models doing flight training.
I know Learjet pilots that say, "If you can get the door closed, it will haul it"
I've seen it a million times at airports.

Do I condone breaking the FARs? No, but I have seen it pretty much as standard practice by people in low useful load planes and no one likes a whistleblower.
 
Ok, good, you're a creature of understanding and are asking the right questions. The answer is the there is more to it than climb on a given day. There are structural loads to consider with the potential multipliers in load factor increases from turbulence or max G maneuvering. Also consider structural issues with tires an landing gear on those 'less than perfect' landings.

The determination of GW is not a single simple equation, it is complex multifunction calculus. It is not set to protect you in the mean of the operational curve, it is there for when you reach the bell mouth.
 
Maverick3n1 said:
It still goes to point out that nobody has truly given a real solid answer to why the numbers are the way they are, and yet they seem to be skewed between what the recommendations are and what people actually follow. Especially in the case of the Light Sports, where some random number was placed to call an aircraft "light sport" whether or not it could do more. They aren't looking at structural capability. They are looking at classification requirements for their rules, as if I recall correctly, a light sports pilot does not require as much training as a private pilot.
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Because there is no FIXED answer. Engineering of all types is an art of compromise, that is why the answer is "Made up", because engineers decide what specs whatever they are designing should meet, or there are regulations that someone has set for some reason that say what they must accomplish, e.g. the example of light sport being allowed only to a specific MTOW. Then the plane is designed to at least meet and/or exceed those specs.

You can't get everything you want because one design goal is opposed by another one. Engineers determine WHAT they want the plane to do and the design a plane to accomplish those goals.

It's all about design with a margin of safety. Nearly any parameter can be graphed out, there is a cutoff for every parameter. There is a weight at which a plane simply will not get airborne, but that's not where they want to set the limit since the desire is to fly. They set the limit with an expected margin of safety to achieve that goal.

As I stated previously, there are many instances where a plane is "re-certified" for a new gross weight, it happens all the time. Often the re-certification is for a substantial increase, often with minimal changes. I am familiar with diamond aircraft, look at the history of the DA40.

http://poweredbylycoming.blogspot.com/2007/08/da40-gross-weight-increase.html

quoting for this blog post which contains the service bulletin for the weight increase...."No modifications needed to the structure, since our DA40 had the 18mm MLG struts, all we needed was a couple of bushings installed to limit the elevator travel. 1 hour of work later, and we've got another 110lbs of useful load!"

So the engineers determined that to stay within the limits of their design but carry additional load of 110 lbs all they needed to do was limit elevator travel to limit the degree of aggressiveness of maneuverability. The airplane and airfoil was capable of carrying the weight the whole time....
 
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Maverick3n1 said:
So I ask again. Why does it seem to be something where people commonly break these limits, yet they are listed as though if you break them, you exceed the limitation of the plane and will probably crash?
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Because you probably won't crash.

Look, there is no magical threshold. The more you add weight, the higher the likelihood that the wing will no longer be able to support that weight, or that the landing gear will break on a rough landing, or any number of things. Is it certain to happen? of course not. It's a combination of weight, and conditions on a particular day, and this and that. You might be taking off at 100lb over gross in a 172, remember you forgot something in the car, fly around the pattern to land, come in nice and slow on final and suddenly stall at the normal low-range approach speed and hit the ground left wingtip first 100 feet short, which would be a bummer. But you will very likely land with no trouble whatsoever on most days. Do it with 200lb over gross and the likelihood of nose planting increases. Most times nothing bad will happen, so you will learn from that and decide it's perfectly fine, and then one day conditions will be such that the extra weight suddenly makes a perfectly good takeoff on another day become impossible, which you only realize after you've run out of runway. It could even happen when you are INSIDE the stated envelope, too. Those numbers make a lot of assumptions, and changing any one variable, like DA, will impact the end result.

Let's also not forget the role that liability plays.
 
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Gross Weight is usually limited by this and other regulations similar

This is why gross weight increase type STC's on small aircraft usually limit flap extension and have no structural reinforcement for the increased weight.

§23.77 Balked landing.
(a) Each normal, utility, and acrobatic category reciprocating engine-powered airplane at 6,000 pounds or less maximum weight must be able to maintain a steady gradient of climb at sea level of at least 3.3 percent with—

(1) Takeoff power on each engine;

(2) The landing gear extended;

(3) The wing flaps in the landing position, except that if the flaps may safely be retracted in two seconds or less without loss of altitude and without sudden changes of angle of attack, they may be retracted; and

(4) A climb speed equal to VREF, as defined in §23.73(a).

(b) Each normal, utility, and acrobatic category reciprocating engine-powered and single engine turbine powered airplane of more than 6,000 pounds maximum weight, and multiengine turbine engine-powered airplane of 6,000 pounds or less maximum weight in the normal, utility, and acrobatic category must be able to maintain a steady gradient of climb of at least 2.5 percent with—

(1) Not more than the power that is available on each engine eight seconds after initiation of movement of the power controls from minimum flight-idle position;

(2) The landing gear extended;

(3) The wing flaps in the landing position; and

(4) A climb speed equal to VREF, as defined in §23.73(b).

(c) Each normal, utility, and acrobatic multiengine turbine powered airplane over 6,000 pounds maximum weight and each commuter category airplane must be able to maintain a steady gradient of climb of at least 3.2 percent with—

(1) Not more than the power that is available on each engine eight seconds after initiation of movement of the power controls from the minimum flight idle position;

(2) Landing gear extended;

(3) Wing flaps in the landing position; and

(4) A climb speed equal to VREF, as defined in §23.73(c).
 
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You're rolling the dice when you take off overgross. Sometimes you lose.

https://www.youtube.com/watch?v=OVM3RRd1vf0

Four guys in a PA28 or C172 is one of the most popular stupid pilot tricks. These are really sad because the idiots who do this usually take unsuspecting passengers to hell with them.
 
So, here we go again with this topic. The main gist of the comments here is that MGW limits are set so that there are adequate safety and performance margins under typical operating conditions. Every lb over reduces those margins. At some point you run out of structure or performance. When special allowances are granted it is done in exchange for and with full acceptance of a decrease in safety margins. Accepting that risk without mitigating factors such as special training or experience, or operational limits, may not be wise. And the FAA will consider you culpable in the event of an accident.
 
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Nice video, Jim. If you had to guess, how much over gross do you think they were?

I think that is one thing that shocked me the most when I first got into flying, is that most 4 seater aircrafts couldn't actually take 4 people unless they were all tiny women.. The C172 I fly is maxed out with just myself, my instructor, and a full tank of fuel, even though it has 2 additional seats in the back and luggage storage space.

I do have the advantage of taking off from an airport that's only 300MSL, so I have denser air than many other places, but I just would have expected that if an airplane was going to be designed with 4 seats in it, they would make it structurally sound to take 4 people and full fuel. I know a lot of people like to use the 150/152 as a trainer, but that one kind of stumped me as well, as it's weight limit is similar to the light sports. Myself and my instructor in it with no fuel would be over-weight. Yet to my knowledge, it's one of the most popular trainer aircraft. It looks like I need to lose some weight ;)
 
Maverick3n1 said:
I think that is one thing that shocked me the most when I first got into flying, is that most 4 seater aircrafts couldn't actually take 4 people unless they were all tiny women.
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Most light singles of 4+ seats can typically legally carry 2 less than available seats with full fuel and some baggage. Two seat trainers typically can carry two FAA sized adults and a toothbrush with full fuel. My AA1A was not a good traveling plane if you wanted company. My AA5 will carry 2 plus a boatload of luggage/shopping loot.
 
I would point out that even if the loads don't reach the level of immediate failure, there are also long term fatigue effects to be considered. IOW, without ever reaching the design limit load, you could still reduce the life of life-limited components, or turn non-life-limited components into limited life components -- without knowing what that limit is.

All things considered, operating over book max gross is (in polite terms) unwise, shirt-sighted, and imprudent.
 
Maverick3n1 said:
I think that is one thing that shocked me the most when I first got into flying, is that most 4 seater aircrafts couldn't actually take 4 people unless they were all tiny women.. The C172 I fly is maxed out with just myself, my instructor, and a full tank of fuel, even though it has 2 additional seats in the back and luggage storage space.
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I think your surprise comes from the fact that you're considering full fuel to be the default. You shouldn't expect to be able to fill the tanks and still put a person in every seat.

If you can fill the tanks, and still put an average person in every seat and baggage in the baggage compartment, your fuel tanks are too small. You want there to be some air in the tanks when you're maxed out on payload, that means you can take extra fuel when you have a light payload.

Instead of judging the aircraft based on 'full fuel', which is arbitrary, it makes more sense to judge it based on some certain endurance or range. "It can carry ____ with _____ hours of fuel", or "It can carry _____ for ______ miles before you have to stop for gas".
 
Maverick3n1 said:
I think that is one thing that shocked me the most when I first got into flying, is that most 4 seater aircrafts couldn't actually take 4 people unless they were all tiny women.. The C172 I fly is maxed out with just myself, my instructor, and a full tank of fuel, even though it has 2 additional seats in the back and luggage storage space.

[Referring to 150/152] Myself and my instructor in it with no fuel would be over-weight. Yet to my knowledge, it's one of the most popular trainer aircraft. It looks like I need to lose some weight ;)
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FAA standard adult is 170lb. C-172 with 4 adults is 2 hr endurance, or slightly under half tanks - perfectly usable.

As for 2 seaters: the 150 has a 500lb useful load, the 152 has a 550lb useful load. For you to be over gross with zero fuel, you and your instructor would both have to be over 250lb. I'm not sure how you'd even fit in the plane if that was the case.
 
Ron Levy said:
I would point out that even if the loads don't reach the level of immediate failure, there are also long term fatigue effects to be considered. IOW, without ever reaching the design limit load, you could still reduce the life of life-limited components, or turn non-life-limited components into limited life components -- without knowing what that limit is.

All things considered, operating over book max gross is (in polite terms) unwise, shirt-sighted, and imprudent.
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I would be surprised if those 207s up in Alaska with 40,000 hours on them have never flown over gross
 
Maverick3n1 said:
Nice video, Jim. If you had to guess, how much over gross do you think they were?

I think that is one thing that shocked me the most when I first got into flying, is that most 4 seater aircrafts couldn't actually take 4 people unless they were all tiny women...)
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It's a bad design if you can fill the tanks and fill all the seats with FAA standard adults. Having the trade offs makes the plane more usable. If the pilot is not an idiot.

I suspect the accident airplane wasn't way over gross, but combined with high density altitude he was over gross for that day and place. Notice also that he didn't have or didn't wear a shoulder harness. That's also something that identifies really stupid pilots.

Most of these types of accidents are not 'way over gross'. They just combine 'a little bit' over gross with a downdraft, wind change, hot day, or a stall while trying to turn.

Actual structural failures in C-172s or PA-28s are very rare.
 
You can fly the airplane significantly overweight and not suffer any ill consequences if you are operating at sea-level, fly conservatively, and stay out of turbulence. The overweight will take its toll at high density altitudes and situations where you are stressing the airframe. You are cutting down your margin of safety but that margin is quite large at the parameters I mention in the beginning.
 
Overweight, high density altitude, perhaps not leaned for best power, etc. are reasons for poor climb performance. The pilot's decision to continue towards higher terrain led to the crash. He had opportunity to turn towards lower terrain or orbit to gain altitude or return to the field.
 
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