Gross Weight

How much is too much over gross weight?

This issue comes up so many times, sometimes I feel like writing an
overgross FAQ. The short answer is - it depends. Now for the long
answer:

Legal aspects:

Even 1 pound over max gross is not legal, and can subject you to civil
penalty - unless you have been granted some deviation. The deviaitons
come in many flavors. Many light aircraft in Alaska are eligible for
up to 15% increases if operated under Part 135 (obviously they fly
differently under Part 91). Some STC's allow you gross weight
increases with certain (often minor) modifications. Some engine change
STC's come in flavors where one gives you a gross weight increase and
the other does not - with the same engine. The FAA will give you a
ferry permit to operate up to 20% overgross without batting an eye if
you show that you understand what you're getting into.

In other words - understand that gross weights are as arbitrary as
speed limits - sometimes they exist for very good reasons, and may give
you very little margin for error (or even none at all, or less than
none), and other times they are arbitrary. It all depends on the
situation. But rest assured the FAA won't see it that way.

So how will you get caught? Well, you could have an accident. You
could be ramp checked - but in that case the overload would have to be
obvious and egregious - nobody will catch you on a 50lb overload. Put
four big guys into a Cherokee 140, though, and you are advertising an
overgross operation.

Insurance aspects:

Your insurance PRIMARILY covers you for pilot error, since that's
(officially, at least) the cause of most accidents. I've had many
insurance policies, and none have ever excluded coverage when operating
contrary to FAR's.

In other words, the idea that you're uninsured when overgross is a
myth. You're covered if you are drunk, overgross, and fly into an
airport without a clearance. Exemptions are clearly stated. Generally
they require you to have a certificate of a certain grade, certain
hours of experience, and an annual and medical that have not expired.

On the other hand, if you overload and fail to get off the ground, you
may have a hard time getting insurance after about the second or third
time this happens, and you will pay more the first time.

The slippery slope:

If you fly overgross, you're breaking the rules. Where will the
rulebreaking stop? The answer is really nowhere. It's like speeding -
you are substituting your judgment for regulation. Once you've shown a
willingness to do that, you will keep doing it when you feel it's safe
to do so. That's worth thinking about, assuming you never ever break
any regulations whatsoever, not only in your airplane but also in your
car, on your bicycle, etc. Otherwise, that ship has already sailed and
it's not a valid question.

A more on-point slippery slope - if 25 pounds over is OK, what about
50? And next time 100? 200? Where does it stop? That's the valid
question - and it has a valid answer, but not one you're going to like.

Simple light airplanes have a single maximum gross weight - one size
fits all (really one size fits nobody, because it's a compromise). The
bigger and more complex the airplane gets, the less true that is.

Some airplanes have zero fuel weights, because the wing attach points
are a weak point in the design. Some have a maximum takeoff weight
higher than the maximum landing weight, because the landing gear is a
weak point in the design. Some are eligible for gross weight increases
with tip tanks, provided the extra weight is fuel in the tip tanks and
nothing else. And when you get all the way up to the airlines, their
maximum takeoff weight depends on the runway length, the required climb
gradient, and the density altitude - in other words, it's not a single
number, but must be computed for every takeoff.

So how much is too much? It all depends on what sets the limit. On
some Cessnas, the limiting factor is being able to show the required
positive rate of climb with full flaps (40 degrees). Limit flap travel
to 30 degrees, and you get a 100 lb gross weight increase. Suppose you
simply limit travel operationally (and don't install the hardware)? Is
that OK? How about if the selector switch gets stuck in the down
position?

Are you protected if you stay within the rules? You only think so.
The gross weight is the same at 7000 ft density altitude as it is at
sea level - but at that density altitude, the plane will NOT climb with
full flaps at gross. Never forget, these limitations are arbitrary -
staying within them won't necessarily keep you safe, and breaking them
isn't necessarily dangerous.

It is possible (but not legal) for you to do the same thing the
airlines do - come up with your own calculations and procedures.
Sufficient data exist in the average POH to extrapolate performance
curves for various operations above gross weight, so you can estimate
takeoff, landing, and climb performance, compute new operational
speeds, etc. You can study the design, and the available modifications
and authorizations, to determine if it is performance, rather than
structural integrity of some component, that limits gross weight. You
can consider the nature of the flight - perhaps 3.0 positive gee limit
is sufficient on a smooth VFR day. In other words - you can approach
operation outside the established envelope the way a real, modern test
pilot does it.

Can the average private pilot do this? Will he? No, and no - and
that's why the rules are what they are. They are written to the lowest
common denominator.

Can you learn how to do it? Probably. If you have sufficient
technical background, you may do it on your own. Or someone can teach
you - but who? Not this guy:

I know that when I was receiving training, my instructor
once had me bring 2 male adults with me to a lesson.

He then had you project performance and handling characteristics by
extrapolating from the POH and maybe other sources. In flight, he
discussed these issues with you so you would know how to handle the
situation in the future, pointing out quirks of the operation. No? He
just told you to get in and go?

I wish that were the exception, but it's the rule. He was teaching you
how to fly overgross, and he was doing about the worst possible job of
it. Yeah - you did it in that particular instance. You learned a
little - mainly, you learned that operating outside the published
envelope has consequences, and a bit about what they can be. But
without an underlying framework for understanding, all you learned is
what happens in that one specific case. Since that specific case is
unlikely to be repeated exactly, you haven't really learned anything
very useful.

So the answer to your question of how much is too much? When the
safety margin associated with the limiting factor in play under the
circumstances becomes uncomfortably slim, that's too much.

Michael

"Dale" wrote in message
...
In article ,
"Hotel 179" wrote:

If you are flying in Alaska, the regs allow a 15% fudge factor if you are
below a certain weight.

Not true. The 15% increase is for specific airplanes with approval.

--
Dale L. Falk
-------------------------------------------reply---------------------------------------

A very general statement about a hypothetical situation should have
read"...below a certain weight in a specific aircraft with approval."

I didn't cite the regulation because it was just a what-if about 40 pounds
in a C172. I stand corrected.

Stephen
Foley, Alabama

"Test pilot" is a little extreme. Let's just say that none of the
performance numbers in your flight manual mean anything when you operate
over gross.

Bob

"Fred Choate" wrote in message
...
You are right Bob.....I agree. But I was hoping for discussion on the
topic, not whether my old instructor did a good or a bad thing.....
(But I do agree with you about my old instructor. That lesson should not
have been flown, but on the upside, I did learn from it)

I chatted with an instructor down at my FBO after my discussion at work,
and his spin was "once you go over the max weight, you are essentially a
test pilot". I hadn't heard that one before, and will remember it.

Fred


"Bob Gardner" wrote in message
...
You'll never convince the FAA that anything over gross is legitimate
(unless you are in Alaska). If you have an accident/incident, your
insurer will not be impressed either. Your instructor was a dork to let
you break the rules during an instructional flight (duh!). Not the best
way to train safe pilots.

Bob Gardner

"Fred Choate" wrote in message
...
Here is a topic that was of discussion at work today:

How much is too much over gross weight? For example.....the 172 has a
gross weight of 2300 lbs, but what if you are 2345 at time of
takeoff.....is that too much over, even if you are going to be burning
enough fuel before your first scheduled stop to be under weight for
landing?

What about airframe age, prop age...etc? Does it make a difference on
decision to "carry a little extra"?

I know that when I was receiving training, my instructor once had me
bring 2 male adults with me to a lesson. That put 4 male adults in a
172 with full fuel. I don't recall the specific weight we were at, but
we were over weight. The airport we flying out of had 8000' of runway,
and my instructor had me doing pattern work. The aircraft was very
clumsy, and made me really work at flying it. I didn't like that
feeling at all! It was a good training day.

Anyway, it was a good discussion between a few of us at work, so I
thought it might make a good topic here.

Fred

On Fri, 08 Jul 2005 08:18:12 -0400, Stubby
wrote:

I'm met a few USAF test pilots. None of them ever talked about flying
over max weight.

During WWII, my impression is that nearly all the escort fighters and
for sure all the bombers were over gross for every mission. All the
weight was where it needed to be, relatively, although gunners had a
habit of loading in extra flack jackets to stand on. The bombs were
right at the C of G and the majority of the fuel tanks were. The P-51
Mustang had a 75 gallon fuselage tank that was aft of the pilot and
made the fighter seriously sensitive when full. Normal procedure was
to select that one immediately after takeoff to burn it off and bring
the C of G into spec.

Takeoff in the bombers was always harrowing and most of the time
nearly the entire runway was used with the bombers laboring airward
for several hours to get to mission height and form up.

Yes, there were LOTS of accidents. I've read that most casualties and
fatalities occured from training and operational accidents, rather
than from enemy activity. That would likely have been more so for the
fighters than for the bombers, because the fighters could and did
normally avoid flack when on escort. But the bombers had to plow
right on through it. Imagine looking ahead over the target and seeing
a black cloud dead ahead, filled with flashes of exploding shells, and
you have to fly directly into it. Every human instinct would be to
turn away.

On the other hand, later in the war the fighters were often released
from escort duty after bringing the bombers safely to the target,
whereupon they were ordered to strafe targets of opportunity. That
brought them down into the sights of the light AA and the Germans were
very very good at putting up curtains of cannon fire around valuable
targets like airfields.

Some of best known pilots were shot down by flack, rather than by
other airplanes. Francis Gabreski, for one. Robert Stanford Tuck for
another.

Corky Scott

"Michael" writes:

[...] In other words, the idea that you're uninsured when overgross
is a myth. You're covered if you are drunk, overgross, and fly into
an airport without a clearance. Exemptions are clearly stated.
[...]

As a contrary data point, my (Canadian Marsh/Lloyds) insurance
includes an explicit requirement to stay within W&B limits to retain
coverage.

- FChE

Jose wrote:
If your limit is 45 over gross, how far over your limit is ok?



It depends on the aircraft. Some are more capable than others. It depends on
the weather. I'm more willing to carry a load in cold weather than hot. Less
in cold wet weather. And it depends on how bad do I need to get there with the
load. And what the consequences are of not doing it.

There is no simple pat answer.... unless you tend to think in terms of black and
white.




--
Mortimer Schnerd, RN

VE

Mike,
I like your post. I was thinking today about how a pilot would approach
flying a brand new 172, versus a mid 70's 172. Would the pilot look at the
performance differently, thinking that the new bird would handle it better
than the older one?

Fred

"Mike Granby" wrote in message
oups.com...

One could argue that the speed limit is a lot more of
an arbitrary number than an aircraft's gross weight figures.

Like the max gross on the Warrior 161 that can be changed by putting a
sticker in the POH? Or the max gross in that Cessna that can be changed
by limiting the flap travel? Or the max gross on the PA-32-260 which is
the same as that on the PA-32-300, despite having a lot less power for
take-offs in marginal conditions? Once you start deciding for yourself
what is acceptable and was isn't in terms of speed, and ignoring the
"experts" who set the limits, you're in the same position as busting
max gross. You're thinking for yourself, and ignoring the rules. Thus,
if one is likely to make you an across-the-board rule breaker, so is
the other. There are good arguments against over weight operation, but
this slippery-slope argument isn't one of them.

Also, let's do away with this by-the-book argument. None of us fly
light aircraft by the book. We don't take-off from fields that are
*exactly* what is stated as required by the book and we don't land into
fields that are *exactly* what the book says we need to stop. We add a
safety margin that we are comfortable with, and that is based upon our
own experience of the aircraft that we've built-up over time. The book
figures are, as we always reminded, with a new aircraft with a pilot
who is probably a damn sight better than we are. So, since our aircraft
aren't new, and since we're not that good, we might as well say that on
every take-off, we're a test pilot, since we're operating in conditions
that aren't documented in the POH.

The fact is that over-weight operation is not particularly dangerous
unless you're out of balance or in marginal conditions re the take-off
in the first place. The structural effects aren't going to be a
problem, and the stall speed effects aren't going to be a problem. The
failure mode that matters is failing to get out of ground effect, or
failing to get into the air at all. And that is something that can
happen whether or not you stick to max gross, and that you have to use
your judgement to decide upon based upon your knowledge of the airplane
and what you're comfortable with. So while it isn't legal, it isn't
particularly dangerous, and it is far more common than most people
would admit.

That is interesting. I will start re-reading. Thanks for pointing that
out.

Fred


"Bob Moore" wrote in message
. 121...
"Fred Choate" wrote

How much is too much over gross weight?

Terminology...terminology...terminology :-)

Where did you guys pick up the term "gross weight" with
regard to aircraft operating limitations? The FAA sure
doesn't use it and I understand it to mean what ever the
airplane weighs at some particular time.

From Part 23:

Section 23.3: Airplane categories.
(a) The normal category is limited to airplanes that have
a seating configuration, excluding pilot seats, of nine
or less, a maximum certificated takeoff weight of 12,500
pounds or less,

Section 23.25: Weight limits.
(a) Maximum weight. The maximum weight is the highest weight
at which compliance with each applicable requirement of this
part (other than those complied with at the design landing
weight) is shown. The maximum weight must be established so
that it is-

Note the use of "Maximum Certificated Takeoff Weight" and
"maximum weight".

At some airlines, I have seen references to "Maximum Gross
Weight" and "Actual Gross Weight", but never just Gross Weight
meaning a certificate limit.

Bob Moore

Exactly what we were discussing at work.....

I guess maybe it might relate to how many drinks can I have in a specified
period before driving home.....

Fred

"Jose" wrote in message
m...
As a practical matter, if being 45 pounds over gross makes the difference
between somebody going or being left behind, I can tell you that you'll
be as popular as a turd in the punchbowl if you leave that person behind.

Leave some gas behind and alter your flight plan if necessary.

If your limit is 45 over gross, how far over your limit is ok?

Jose
--
Nothing takes longer than a shortcut.
for Email, make the obvious change in the address.

Right. I also like how you put that.

Fred

"Paul kgyy" wrote in message
ups.com...
Addressing this as an intellectual problem, "it depends". With CG in
the middle of its range, smooth air, low density altitude, aircraft and
engine in excellent condition, a long runway, and a pilot capable of
flying and landing smoothly, I'd guess most light planes would easily
handle 10% over certificated weight. Long range ferry pilots often
take off overloaded, and I understand it's also common practice in
Alaska, where many of the above conditions do not exist.

Interesting to see how many people get fired up about this. When you
fly, you have to use your brain for all aspects of the flight, not just
quote the rules.