Flying Over Gross

[HerrGruyere]

I took my buddies flying this weekend, but since we're all tall fellas, I had to give two separate rides. This got me thinking: what happens when you fly over gross weight? I encountered two possible scenarios:

1) If I had stuffed both of them in the plane with full tanks, that load would be 921 pounds. The maximum load is 750 pounds. What would have happened if I gave it a go?

2) If I had stuffed both of them in the plane, but the tanks were just over half full, resulting in a gross weight of about 780 pounds. What would have happened if I had tried to fly being only 30 or 40 pounds over the limit?

Naturally, I didn't want to try to find out the end result. I reckon flying only 30 or 40 pounds over gross wouldn't be as bad as I think, but I believe 171 pounds over gross might make a huge difference.

For the record, I couldn't fly them both at the same time, anyway. My buddy and I are both 6'2" and 185, but my other friend is about 6'6" or 7" and 220. He could barely fit in the front seat, and putting him in the back was hilarious.

 

[tmyers]

All I know is that the aircraft were flight tested to perform with a weight and lever arm that corresponds with the chart you have for your aircraft. I think the real question is if there is some measure of safety build into the limits in your POH.

I am sure there is a small margin of safety built in but basically flying out of the box makes you a test pilot. Nasty things can happen when you fly outside the box.

 

[bflynn]

The answers -

If you're just a little over gross, you get bad performance. You climb slowly, you stall at a higher speed, etc. Possibly this gets you into trouble on the flight because the airplane performance is a little unpredictable and you're making a test flight with your friend. Probably it gets you into trouble on later flights because now you've flown outside the airplanes certificated performance envelope and you're willing to do it again.

If you're a lot over gross: The airplane won't take off or worse will mush along just above stalling speed while you try to figure out the new handling characteristics of this airplane. This ends in a crash. You probably hurt yourself and your friends, maybe kill all of you.

Airplanes have weight and balance for a reason.

The NTSB accident report should probably contain the phrases:
(2) Pilot expected performance wildly beyond capability of the aircraft (high density altitude, Wintertime climbout from big rocks, four in a C172 with full fuel, Baron with five up and full Fuel and uphill runway eg. St. Ignace accident, etc).
(5) Pilot was a scofflaw (no medical, out of annual, no BFR, “What-did-you-expect”).

 

[LDJones]

The plane probably would have flown the heavy scenario better than you think, although your takeoff roll would have even longer than you've likely seen. But recognize you're a test pilot at that stage, and have cut all safety margins in the design significantly. Stall speed also goes up, as well.

Ferry pilots often fly plans well over gross, but know they won't be landing that way and fly it pretty cautiously til the weight goes down.

At 30 over it probably wouldn't feel much different than at gross, but it would get noted in the accident report if you screwed up.

The obvious right answer is don't find out what would happen over gross. Enjoy the safety margins for what they are there do and keep you and your passengers safe.

 

[Fearless Tower]

What happens is you become a test pilot. Legallity aside, this time of year, given suffuicient runway and low DA, you probably would have been able to takeoff and land safely....although landing overgross could overstress the airframe. Most folks who get FAA paperwork to exceed gross for overseas ferry operations land well under gross due to fuel burn enroute.

Bottom line is that your performance will be degraded, but how much? You'll get to find out since you are playing the test pilot.

 

[JHW]

nearly everyone has flown over gross by 30-40 lbs. Some are even blatant about it, you'll see it in every thread about weighing the airplane: "I refuse to put my plane on scales because I might lose some useful load"

 

[douglas393]

nearly everyone has flown over gross by 30-40 lbs. Some are even blatant about it, you'll see it in every thread about weighing the airplane: "I refuse to put my plane on scales because I might lose some useful load"

Nearly everyone, I hope not, but maybe you are right and I am just naive. I personally do not want to be a test pilot, I have more than enough drama in my life, I try to make sure flying is not one of them. Flying is my relaxation and my way to get away from it all.

 

[wabower]

The "you become the test pilot" pablum isn't necessarily true. Some off-the-shelf planes, including the B-200 King Air, are flown by the military using different POH limitations than those for civilian ops. For example, the 12,500# max gross weight limit is increased to 14,000# with performance charts and CG envelopes published for all weights. The differences in performance at higher weights aren't a big deal.

Load isn't nearly as important as CG. Bottom line is that the plane will usually fly with almost anything you can stuff inside, assuming atmospherics and adequate runway and climb margins, so long as CG is within the expanded hypothetical envelope. Garrison published a lengthy and well-researched article on the subject a few years ago in Flying Magazine that quantified the impact of extra weight.

What happens is you become a test pilot. Legallity aside, this time of year, given suffuicient runway and low DA, you probably would have been able to takeoff and land safely....although landing overgross could overstress the airframe. Most folks who get FAA paperwork to exceed gross for overseas ferry operations land well under gross due to fuel burn enroute.

Bottom line is that your performance will be degraded, but how much? You'll get to find out since you are playing the test pilot.

 

[LDJones]

The "you become the test pilot" pablum isn't necessarily true. Some off-the-shelf planes, including the B-200 King Air, are flown by the military using different POH limitations than those for civilian ops. For example, the 12,500# max gross weight limit is increased to 14,000# with performance charts and CG envelopes published for all weights. The differences in performance at higher weights aren't a big deal.

Load isn't nearly as important as CG. Bottom line is that the plane will usually fly with almost anything you can stuff inside, assuming atmospherics and adequate runway and climb margins, so long as CG is within the expanded hypothetical envelope. Garrison published a lengthy and well-researched article on the subject a few years ago in Flying Magazine that quantified the impact of extra weight.

Yep....pretty much what we said. But if you don't have the data for operating at those higher weights you're finding out what those limits are through testing...hence, a test pilot.

 

[Fearless Tower]

Yep....pretty much what we said. But if you don't have the data for operating at those higher weights you're finding out what those limits are through testing...hence, a test pilot.

Exactly....someone else may have been there and done that, but without their data....you might as well be doing it for the first time.

 

[wabower]

The difference is in understanding the impact rather than invoking the hushed "test pilot" tones during the discussion.

Exactly....someone else may have been there and done that, but without their data....you might as well be doing it for the first time.

 

[JHW]

Nearly everyone, I hope not, but maybe you are right and I am just naive. I personally do not want to be a test pilot, I have more than enough drama in my life, I try to make sure flying is not one of them. Flying is my relaxation and my way to get away from it all.

you're missing the point. If you regularly calculate that you are right at gross weight then odds are you have many times been over gross due to inaccurate aircraft weight W&B.

 

[Fearless Tower]

The difference is in understanding the impact rather than invoking the hushed "test pilot" tones during the discussion.

I don't think it is 'hushed'. Just a simple two word phrase to indicate you are venturing into the unknown.

The point is you know that performance is going to be less, but you don't know how much. You know your are going to use more runway than the book says...but you really are entering a unknown realm when you operate there. You are off the chart and interpolating data off the chart may or may not be very accurate.

That doesn't mean you will fall out of the sky, pop the chute and burst into flames, but you are taking on a considerably greater amount of risk than if you stick within designed parameters.

 

[JHW]

The difference is in understanding the impact rather than invoking the hushed "test pilot" tones during the discussion.

when I worked for privett all of our B200's were operated at US military weights and approved as-such on our operating certificate. In fact I was at that weight limit when I got rolled by a 757. I'd guess that the northern hemisphere air produces similar performance as what I observed there.

OTOH our AN24's were restricted by operating certificate to 472kg less than the russian performance charts said. That being such a precise number I always wondered who came up with it and why.

 

[tmyers]

I am sure weight and balance envelopes were and are developed with a thought as to the losses in the eventual court battle, meaning safe squared. If I remember right form my research the PA28-161 (Warrior) line has a gross weight increase with a piece of paper, go figure that one.

I would also think that the manufacturers that were fighting for market share would publish the max weight as high as safely possible to sell more aircraft. I know if my Arrow had a max takeoff weight of 3000# instead of the 2750# I would be dancing. That would be like 250# of gold when comparing to a Rockwell, or a Cardinal and would even put it in a class with the 182.

Since they didn't, my simple brain tells me there must be a reason.

I have never knowingly flown an airplane above max gross and with my Arrow I perform the mathematical lever arm calculation since a pencil width on the (IMO) weak W&B charts in the POH can throw things off by 50#.

But that's just me, your mileage may vary.

 

[Fearless Tower]

you're missing the point. If you regularly calculate that you are right at gross weight then odds are you have many times been over gross due to inaccurate aircraft weight W&B.

I understand your point, but think you might be blowing it out of proportion a bit.

I know most owners aren't terribly diligent about keeping their W&B updated, but I also have never heard an owner say (in anything other than jesting) the comment about not wanting to lose useful load as a reason for not updating the W&B. Also, the weights we are talking about from not updating a W&B are typically small in the grand scheme of things. When I had my 170 weighed when I bought it (last one had been over 20-30 years before), it gained around 15 lbs. I don't think I have ever loaded an airplane so close to max gross that 15 lbs would have made a difference.

 

[wabower]

Guess it depends on whether you wrote it or read it. Since a high probability exists that many pilots will encounter such a situation over their careers, why not just provide some useful input rather than the "boogey-man gonna get you" admonitions?

I don't think it is 'hushed'. Just a simple two word phrase to indicate you are venturing into the unknown.

The point is you know that performance is going to be less, but you don't know how much. You know your are going to use more runway than the book says...but you really are entering a unknown realm when you operate there. You are off the chart and interpolating data off the chart may or may not be very accurate.

That doesn't mean you will fall out of the sky, pop the chute and burst into flames, but you are taking on a considerably greater amount of risk than if you stick within designed parameters.

 

[HerrGruyere]

Thanks for the answers everyone!

Just to clarify, I would not have actually flown the aircraft whether it was 20 or 200 pounds over gross. No way. I just wanted to see the answers to a hypothetical situation.

 

[wabower]

In that case you might want to order some of those reality check pills they sell on the internet.

Thanks for the answers everyone!

Just to clarify, I would not have actually flown the aircraft whether it was 20 or 200 pounds over gross. No way. I just wanted to see the answers to a hypothetical situation.

 

[Fearless Tower]

Guess it depends on whether you wrote it or read it. Since a high probability exists that many pilots will encounter such a situation over their careers, why not just provide some useful input rather than the "boogey-man gonna get you" admonitions?

Please tell me why a high probability exists that many pilots will encounter a situation like that?

I think you read it wrong. I was not implying that the boogey-man was going to get anyone. I was implying that the pilot would be venturing into the unknown and combined with the legality involved, it probably isn't worth spending too much time pondering it.

 

[Henning]

I took my buddies flying this weekend, but since we're all tall fellas, I had to give two separate rides. This got me thinking: what happens when you fly over gross weight? I encountered two possible scenarios:

1) If I had stuffed both of them in the plane with full tanks, that load would be 921 pounds. The maximum load is 750 pounds. What would have happened if I gave it a go?

2) If I had stuffed both of them in the plane, but the tanks were just over half full, resulting in a gross weight of about 780 pounds. What would have happened if I had tried to fly being only 30 or 40 pounds over the limit?

Naturally, I didn't want to try to find out the end result. I reckon flying only 30 or 40 pounds over gross wouldn't be as bad as I think, but I believe 171 pounds over gross might make a huge difference.

For the record, I couldn't fly them both at the same time, anyway. My buddy and I are both 6'2" and 185, but my other friend is about 6'6" or 7" and 220. He could barely fit in the front seat, and putting him in the back was hilarious.

As long as you had sufficient runway and clearway to takeoff and climb, it would have been fine most likely. If you had to return immediately with the full tanks, you may do damage, especially since you aren't used to the plane's handling at those weights and the landing needs to be a good soft one. If the flight were discovered and/or reported, you would have to comply with the manufacturers instructions for inspection on a post over gross flight.

 

[wabower]

Because it happens. Extra bag, mistake on fuel order, want to take the tool box, passenger bigger than advertised, yada yada.

Well, that's the problem with words. If you're interested in a small wager, we could put it to the test and ask pilots what they think it means when somebody tells them they are about to become a test pilot.

Please tell me why a high probability exists that many pilots will encounter a situation like that?

I think you read it wrong. I was not implying that the boogey-man was going to get anyone. I was implying that the pilot would be venturing into the unknown and combined with the legality involved, it probably isn't worth spending too much time pondering it.

 

[Fearless Tower]

Because it happens. Extra bag, fuel order wrong, want to take the tool box, passenger bigger than advertised, yada yada.

Simple answer - it isn't legal.

Would you advocate a PIC allowing PAX to pressure him into making a flight overgross because they both want to go?

 

[Henning]

Nearly everyone, I hope not, but maybe you are right and I am just naive. I personally do not want to be a test pilot, I have more than enough drama in my life, I try to make sure flying is not one of them. Flying is my relaxation and my way to get away from it all.

Test pilot is not about drama. Test pilot is about finding numbers. Over gross performance can be calculated on the ground derived from performance at gross.

That said, there is no reason for you to fly over gross and the less weight you carry, the safer and more efficient you are.

 

[docmirror]

I'm not sure of the regs, and not going to look it up but I think I recall that if you fly in AK you get an automatic bump in gross. Maybe 10% or something? So if you're gross in the lower 48 were 2600#, you could legally take off at 2860 in AK.

Also, one more in the strange file for the early Bonanza. The first ones came out of the factory with 185 or 196HP. They were also certified to max gross at utility category. The factory allowed, and even encouraged early plane owners to upgrade the engine to 225HP, a nice boost of 40HP or about 13-20%. If a Bonanza owner can tolerate the lower level of certification to normal category when overgross it would be a minimal issue to operate over gross. Sadly, when Beech authorized the increased power, they didn't go the extra distance and cost to up the gross weight. As for the loading, it's a simple matter of jacking the loading graph 260#, the curves remain the same.

 

[tmyers]

This is a bit off topic but the discussions brought this to mind.

Long long time ago I flew the family (wife and two kids 2 and 4 years old) to Wilmington, NC in a club 180D. Headwinds both directions.

We are at the airport with the in-laws and I am weighing everything i put in the airplane. She couldn't fathom that weight could be so important.

I pull the airplane out with little effort because the hanger floors had a slight slope toward the ramp. She was further horrified that the airplane weighed so little that I could pull it around with that little tow bar.

To to top it all off I had filed IFR for the trip and for some reason they vectored me north about 20 miles before turning me on course to the SE. All the in-laws could see was that I was flying in the wrong direction to go to NC, and they were sure I was going to end up in Canada somewhere.

 

[JHW]

Simple answer - it isn't legal.

Would you advocate a PIC allowing PAX to pressure him into making a flight overgross because they both want to go?

do you really think you can tell the difference ? Do you put each passenger on a bathroom scale as they get in the plane ?

 

[ronnieh]

Wayne, as you see sometimes the simple truth will bring you some grief on this board. I am not putting words in Wayne's mouth but, he may be coming at this from a corporate world prespective.
The OP's decision was fine for his circustances and I suspect Wayne would agree. To me Wayne is talking about the real world. Some on here may honestly say they have never flown over gross and very early on that may have been true for me.
I suspect in a fixed gear, fixed pitch prop, 4 place aircraft a 5% over gross would be very hard to discern by the average pilot and doubt it would make any difference as long as CG was reasonable.
However in my world the biggest concern on weight is single engine performance. I do pay attention to that and especially aft CG since this has a great affect on SE performance.
But, as I think Wayne is pointing out, if the boss shows up with two extra people and luggage we are still going. Of course I will do some quick mental calculations especially CG but, chances are we are still going. Might even ask one of the passengers if they would like to ride up front. The Cheyenne tended to be tail heavy.
Sooo, I have to agree with Wayne in that it is done quite a bit. Just the real world verses the make believe world.

 

[wabower]

Nope, and if I'm going to a fly-in for the day I don't take my ball-cap, water bottle or folding chair if the weight looks close. A guy can't be too careful about that stuff.

Simple answer - it isn't legal.

Would you advocate a PIC allowing PAX to pressure him into making a flight overgross because they both want to go?

 

[Fearless Tower]

do you really think you can tell the difference ? Do you put each passenger on a bathroom scale as they get in the plane ?

Maybe I am just overly conservative.....I have always (and will continue to do so) operated GA aircraft with enough of a safety margin in Gross Weight to account for any under-estimated weight. And while you may not be able to tell exact weight, you can usually tell if a fat pax is BS'ng you.

 

[JHW]

Nope, and if I'm going to a fly-in for the day I don't take my ball-cap, water bottle or folding chair if the weight looks close. A guy can't be too careful about that stuff.

If we are taking the travel air I tell my wife she has to pack for the trip to the airport in her volkswagon. If we're in the C414 she has the option to drive her Sequoi. We haven't crashed yet so I guess those cars are the right size.

 

[Fearless Tower]

Wayne, as you see sometimes the simple truth will bring you some grief on this board.

It isn't the simple truth that is the issue.

Issue is that Wayne is trying to do what he accused TomD of doing the other day - attempting to bait me. I suspect that Wayne is bored today....as am I.

 

[ronnieh]

Sorry, Fearless I missed the bait. My bad, I will go back and re read.

 

[Dave Siciliano]

I don't want to advocate flying over gross, but it's like many things, understand it and handle it properly and it can be fine. I've owned two airplanes that were certified at one weight, but approved to carry more weight if certain mods were made, but not legal unless an STC was complied with which was paper work and placards. So, if I fully understand what's going on, I'm technically illegal but within reasonable bounds.

On my current C90, I can get a 700 pound gross weight upgrade by putting on 10 ply tires and purchasing an STC from Beech for $16,000 which is paperwork and placards.

We flew over gross in the Army almost daily at times.

It's not something someone should just do. But if fully understood and quantified, it can be just as safe; albeit, technically illegal. I certainly don't recommend it, but if necessary and one fully understands it, it can be safe.

Best,

Dave

 

[poadeleted20]

1) If I had stuffed both of them in the plane with full tanks, that load would be 921 pounds. The maximum load is 750 pounds. What would have happened if I gave it a go?

Maybe nothing. Maybe you break something. Just depends on how gentle you are with the plane and how smooth the air is, because no matter how smooth you are, a gust which would normally not damage anything may cause a structural failure somewhere in the plane if you don't adjust your speed accordingly. In any event, takeoff and climb performance will be significantly reduced, and if you have an accident, the FAA reconstruction will show what you did and that won't go well.

2) If I had stuffed both of them in the plane, but the tanks were just over half full, resulting in a gross weight of about 780 pounds. What would have happened if I had tried to fly being only 30 or 40 pounds over the limit?

Again, maybe nothing, or maybe something, but the odds of something bad happening are reduced.

Naturally, I didn't want to try to find out the end result.

Good decision.

I reckon flying only 30 or 40 pounds over gross wouldn't be as bad as I think, but I believe 171 pounds over gross might make a huge difference.

Good reckoning.

For the record, I couldn't fly them both at the same time, anyway. My buddy and I are both 6'2" and 185, but my other friend is about 6'6" or 7" and 220. He could barely fit in the front seat, and putting him in the back was hilarious.

That makes the question moot.

 

[poadeleted20]

I am sure weight and balance envelopes were and are developed with a thought as to the losses in the eventual court battle, meaning safe squared.

I am equally sure they are developed on the basis of engineering analysis, test flying, and FAA certification standards. A review of the certification and design paperwork associated with any production aircraft should prove my belief. I doubt you can find anything to support yours, but if you have something to support your belief, I'd like to see it.

 

[tmyers]

I would assert that the engineering and testing is way more than an equal part of the process, but realize that higher aircraft costs and restrictive regulation (placards everywhere) were put there because someone found a way to extract money from the aviation manufacturers. That being said I am pretty sure the potential legal battles when one of us bends an airplane are there somewhere in the process. No proof and no paper to back it up but pretty sure it is a part of every day life in the world of aircraft manufacturing. I do remember countless articles on the subject of tort reform back in the 80's and that those articles did state that a great deal of the cost of airplanes and their parts were a direct result of the punitive awards in the aftermath of an aircraft accident.
I could look them up but I am not trying to prove anything, just expressing a thought.

 

[onwards]

30-40 over gross is within what I would call a normal margin of error, except maybe for the littlest planes (say, 152's). I'm sure I've done it without realizing it, since some of these calculations are not that precise.

Almost 200 lbs over gross? I suppose not a major issue if you have a 2000lb useful load, but with a 750 useful load, if I had to (don't know why, but let's say), I would be very cautious, certainly not try to take off in anything but super calm weather at close to sea level. I would strongly suggest burning off about 25 gallons before you try to land again.

I honestly hope I never have to try.

 

[denverpilot]

The "you become the test pilot" pablum isn't necessarily true. Some off-the-shelf planes, including the B-200 King Air, are flown by the military using different POH limitations than those for civilian ops. For example, the 12,500# max gross weight limit is increased to 14,000# with performance charts and CG envelopes published for all weights. The differences in performance at higher weights aren't a big deal.

There are also aircraft with the exact same build, that have different certified weight allowances between CAR 23 and modern certification. Or requests by the manufacturer to recertify later models with higher weights to carry the fancy leather seats, with the resulting hit to the takeoff and landing performance tables, or the addition of a MGTOW instead of a lower overall hard limit on takeoff.

 

[docmirror]

I recalled one of the few times my brother talked about his flying in Vietnam. He was a LOcH pilot(Hughes 500 with only a 50cal mounted) most of the time. There was a mission to get some machine gun barrels and a few rounds of 7.62 up to a fwd base. They had two Hueys and kept stuffing barrels and bullets into it until it wouldn't take off. I guess, they finally got enough translational lift by skidding it down the runway until it would lift off and barely climb. The had to do a running landing at the other end in a paddy and dump the stuff out pretty quick. After that he didn't do much W&B on the Hueys.