"Matt Hapgood" <hapgoodm94@alum.darden.edu> wrote:


"""
 Knowing how much fuel you have in flight requires knowing TWO things: 1)
 Burn rate, and 2) Starting usable fuel amount (and knowing how much fuel a
 specific flight will require adds in many more variables).
 
 Unless I have TOPPED my tanks on a completely LEVEL tarmac, even perfectly
 accurate fuel flow doesn't really do much for me.  Because the bigger issue
 is "How much fuel did I have to start with" (does Tony D. come to mind?)?
"""

Tony's accident was caused by a different, albeit related, issue than those you mentioned, that being the THIRD thing you left out of your list... knowing how much of the fuel you have onboard will actually be available to the engine.  Granted, most people know that when they've drawn their tanks down to [what they consider] empty that there is a half or three quarters of a gallon (or therabouts) fuel remaining in each tank as "unusable" that can't be drawn from it due to plumbing and tank geometry issues.  (I know, we should never plan on flying down to that level of no-reserve, but.....) I believe in Tony's case that there were 7 or 8 gallons that couldn't get to the fuel pickup because of an internal venting problem... a situation that he was unaware of (for whatever reason.)  While this was an unusual problem, it did manage to happen once too often for Tony, and might not have been an issue had the delivery characteristics of that tank been tested and documented prior to using the airplane for an extended XC flight that required the consumption of that much of the usable fuel.  Isn't there an old saw out there that says "it's not so much what you think about that can hurt you, it's all the other stuff", or something like that?   This is obviously why we subject our garage-built aircraft to the massive amount of testing that we do, in an attempt to minimize or eliminate the "gotchas" that fall into that "all-the-other-stuff" category.  Just my 2c.

   <Marv>