How do you determine what a "safe" overweight condition is?

Discussion in 'Flight Following' started by Hocky, May 30, 2014.

  1. Hocky

    Hocky Ejection Handle Pulled

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    I'm talking about the gross weight of the plane not an obese pilot.

    I've seen articles where people who are ferrying planes over long distances get some kind of waiver to take off way over the maximum gross weight for that plane.

    How is that determined?
     
  2. warthog1984

    warthog1984 Cleared for Takeoff

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    Either after an engineering review and updating limitations via ferry permit (the legal way) or blind luck and stupidity (the illegal way).
     
  3. Dave Theisen

    Dave Theisen Pattern Altitude

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    You just can't help yourself. Get ready for more flames.
     
  4. Darsh

    Darsh Pre-Flight

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    He's just trying to ask questions that we all had as students. Only difference is that I was smart enough to ask someone who wouldn't call me an idiot for simple curiosity.
     
  5. Jhernandez04

    Jhernandez04 Line Up and Wait

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    Let me guess, the student pilot wants to be over gross going to OSH with lots of propane, dry ice, beer and bbq meat.


    You should just have your own commercial like the mountain man for the 10 calorie Dr pepper. Your a real man, not troubled by lack of experience or getting good advice from those who have lived and done what your wanting to do.


    F it, go for it. I think the use able on a 172 is around 800lbs, load it up to with 1500lbs, but make sure your man speed is 40 knots over what safe people would consider rotating speed. Let us know how you do!
     
  6. JB1842

    JB1842 En-Route

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    You must have missed his other posts. I hope it's a legit question and he is going to listen carefully, instead of his usual retort.
     
  7. Dave Theisen

    Dave Theisen Pattern Altitude

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    Does any of have a copy of the FAR's that is annotated with regs it's ok to break? :)
     
  8. tmyers

    tmyers En-Route

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    I must be gullible, I have not asked that question since I started flying in 1986. I assumed max weight was just that, max weight. I realize that most if not all engineering calculations have some measure of safety factor build in but I never felt I should use that safety factor in an airplane.
     
  9. Hocky

    Hocky Ejection Handle Pulled

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    No it's a serious question, no retorts or anything like that. I just want to know how it is done.

    Is it based on an increased stall speed and/or an increased take off and landing roll? I assume both go up as you start going over max gross weight.
     
  10. Clark1961

    Clark1961 Touchdown! Greaser!

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    I can certainly provide that for you. Talk to Ron if you would like a copy that is annotated and stipulated...
     
  11. Hocky

    Hocky Ejection Handle Pulled

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    Josh I am sorry I implied you have a small d-ck earlier but it was only after you implied the same of me. Can we bury the hatchet now? I would like to treat you to a fine cold beverage at Oshkosh to show my sincerity.
     
  12. Dave Theisen

    Dave Theisen Pattern Altitude

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    Sorry. I have given him the benefit of doubt until now, but when he posts in one thread that he is 200 lbs. over gross with what he is planning on bringing to Oshkosh, and then starts a thread on how to safely determine how much you can be over gross, I give up.
     
  13. Hocky

    Hocky Ejection Handle Pulled

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    Well no of course I'm not going over gross! 200lb's has to go.

    The two threads are not related.

    Sheesh people.
     
  14. JB1842

    JB1842 En-Route

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    Hey man. I'm just calling like I see it. No hard feelings. But it's going to be hard to establish yourself after some of your postings. But yes, I will share a drink with you.
     
  15. Jim Logajan

    Jim Logajan En-Route

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    See page 4-111 "4166. Special Flight Permit for Operation of Overweight Aircraft." in this document, which goes into extensive detail:

    http://www.faa.gov/documentLibrary/media/Order/8130.2G .pdf
     
  16. Hocky

    Hocky Ejection Handle Pulled

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    That's great man!

    Just a small detail I would prefer not to actually "share" a drink if that is okay with you. You have your drink and I have mine and maybe the bottles touch but no more than that.

    See you there.
     
  17. Hocky

    Hocky Ejection Handle Pulled

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  18. poadeleted20

    poadeleted20 Deleted

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    :yeahthat:

    And yes, that's a fair question from a Student Pilot.

    The reason you don't want to do that is that the max gross weight (MGW) is determined by a combination of factors, but mostly structural strength (covering maneuvering loads, gust loads, landing forces, etc) and performance (primarily climb after takeoff/balked landing for light singles, but also keeping the stall speed at or below 61 knots, which is a certification requirement for them). If you load the plane beyond max gross, you have no idea which problem is going to bite you first -- the airplane failing structurally, or the airplane being unable to get into/stay in the air or clear obstructions. Since neither of those is what I would consider an acceptable outcome, I don't load beyond max gross -- and since I really do wish to live to be an old pilot, it's the laws of physics, not the laws of the FAA which really drive me to that position.

    As noted above, the FAA does allow special flight permits to operate aircraft beyond the book max gross for transoceanic ferry flights, but only after a lot of consideration of the engineering data and a pile of operating limitations on the operation (starting with "no passengers", which ought to tell you something about how much the level of risk goes up). Further, a significant number of those flights end up in the water rather than at their destination, and the rescue stories from those make scary reading (the other stories from those are epitaphs, and that ain't good).

    The FAA also has a regulation authorizing certain commercial and Federal operators in Alaska to operate as much as 15% over max gross (but not always that much), but there are a lot of other limitations associated with and special training required for that before you can get the specific FAA authorization to do that. See 14 CFR 91.323 for details.
     
  19. MachFly

    MachFly En-Route

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    Never ask such questions on POA....it's not going to go well.
     
  20. JB1842

    JB1842 En-Route

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    Deal.
     
  21. bullwinkle

    bullwinkle Pattern Altitude

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  22. deltaindia

    deltaindia Pre-Flight

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    I wouldn't go and assume that just because the OP has been asking about flying into OSH with a 20lb propane tank that now he's looking at options for flying over MGW.

    It's quite possible that, as a result of the flight planning discussions here, the thought of weight considerations came up and he began to wonder how people get waivers. Not necessarily for himself, but to understand the why's and why nots.

    From my limited time on this forum, it seems that some people tend to jump to incorrect assumptions that may not always be correct, or are just downright dismissive of others.

    I've read his other posts that ask some odd, sometimes ill informed, questions and also seen his flippant replies to members' responses.
     
  23. bullwinkle

    bullwinkle Pattern Altitude

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    Of course, who could ever even *think* they might be related? And even if they were related, "200lb has got to go" is the correct response to use on a public forum, so your sense of judgment is not *entirely* lacking... :goofy:
     
  24. ClimbnSink

    ClimbnSink Ejection Handle Pulled

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    Trial and error. The problem is getting the error part before the trial part.
     
  25. cgrab

    cgrab Cleared for Takeoff

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  26. bullwinkle

    bullwinkle Pattern Altitude

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  27. cgrab

    cgrab Cleared for Takeoff

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    Probably the same one for the compressed air cartridge I had to use in my inflatable PFD when I helped sail my brothers boat to New York from Annapolis-buy a new one and leave it on the boat when done.
     
  28. Dan Thomas

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    With little airplanes, higher weight often means CG more aft. Going past MGW can easily put the CG far enough back to cause controllability issues. A rather ugly situation.

    Something that puzzles me: Most of us here take max gross weight seriously. And yet, I've seen plenty of comments about highway speed limits being low or stupid or whatever, and where I live, at least, most people speed. And there are some awesome speed-related accidents. Why the disconnect?

    Dan
     
  29. ClimbnSink

    ClimbnSink Ejection Handle Pulled

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    Speed limits are set for revenue enhancement. Stop believing all rules are noble and just. Gross weight and cg is a law of engineering. Speed limits are to make sure there are no innocent men. Even if speed limits were set honestly they would be set for the lowest common denominator.
     
  30. sourdough44

    sourdough44 Cleared for Takeoff

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    O.K., here's what helps, a long runway, sea level, cold temps, extra speed on rotation, a gentile rotation, and 5 extra PSI in the tires.
     
  31. txflyer

    txflyer En-Route

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  32. sourdough44

    sourdough44 Cleared for Takeoff

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    That is one nasty video.
     
  33. cowman

    cowman En-Route

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    Try increasing the load in 10lb increments until you crash. 10lbs below crash weight was the actual maximum.
     
  34. Dan Thomas

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    That's one of the best excuses I've ever heard for justifying violating any rule that I find inconvenient.


    But it's still just an excuse.


    Dan
     
  35. ClimbnSink

    ClimbnSink Ejection Handle Pulled

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    Weren't you complaining about BMI rules in another thread? BMI must be a perfect measure just like speed limits. Violate BMI speed limit and you are a disgusting fatty that should not fly and should pay more for health care.
     
  36. Pinstriper

    Pinstriper Pre-takeoff checklist

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    Pfft! The 172 is not a respectable plane to go to OshKosh. You should know this by now.. Based on his previous posts lol!
     
    Last edited: May 30, 2014
  37. Jim Logajan

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    The amount of risk appears to increase as a continuous function with increasing road speed, while the laws of physics create a discontinuous function of risk with increasing gross weight of airplanes. So in the case of road speeds the risk increases smoothly enough that no one speed stands out as the best place to set the limit. With airplane gross weight there are obvious points where there are distinct inflection points. Other than safety factors, over which one may debate, the failure points are quite distinct.

    The following web page has a simple formula for speed/crash risk and more than you or I care to know about how speed limits are set:

    Methods and Practices for Setting Speed Limits: An Informational Report
    http://safety.fhwa.dot.gov/speedmgt/ref_mats/fhwasa12004/
     
  38. chemgeek

    chemgeek Pre-takeoff checklist

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    Bear in mind that maximum gross weight performance data is based on standard conditions, new engine, and expert pilot technique. Add some density altitude, some age-related airframe weight gain, and a well-used, aging and slightly underpowered engine and you might find MGW operation somewhere between challenging to impractical. And that assumes you don't load outside the CG envelope.

    There is a performance reason MGW values are established, and that has to do with adequate safety margins.Operation over MGW will be with greatly reduced or no margin of safety.
     
  39. Alexb2000

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    I believe this is a perfect question and the answers are not even close to black and white.

    For example the military significantly up-grosses everything from a King a Air to a 707. In Alaska you can fly over gross. As mentioned ferry pilots do it everyday. Several situations are not discrete events, but loads the aircraft is expected to operate with for the life of the airframe. Virtually every cargo and airline pilot has flown over-gross at some point (unless you believe a team of football players in winter clothes average 170lb. Including their carry-ons). Some aircraft get a gross weight increase through an STC for things like engine baffles. Politics, lawyers, marketing all have an effect on the "physics" of the aircraft.

    Fly conservative always (but especially so starting out), learn your bird, pay attention and they all talk to you, eventually the answers become more clear.

    Safety IMO isn't remotely guaranteed by a weight and balance sheet just legality (like the speed limit).
     
  40. Hocky

    Hocky Ejection Handle Pulled

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    Makes sense.