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Lear 35 down approaching Teterboro

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  • 3WE
    replied
    Originally posted by Gabriel View Post
    ...Guess where that comes from?...4 miles...
    LOL- it's beautiful making half-donkey-ass-hat posts after a very quick scan of the flying article, and having Gabe do the deep dive read. I owe you a beer- on my second scan of the article, I did not see ceiling and visibility.

    Seeing that ceiling / visibility is a non issue...I also see that I was right that 5 miles was a bit much since 4 miles is standard...

    OK, good...I get it...the 4 miles (to me) seems like a fat, dumb and happy figure. I am pretty sure I have seen a 3 mile-or-so, near-90-degree base-to-final turn while riding an MD-80, heading West and then South into KKCI...nice gentle bank...plenty of time to straighten it out on final...speed under control...solid airmanship. (Yeah, sure, my foffie side imagined them running a wingtip into the ground...but the reality was Fat, Dumb, Happy, Stabilized).

    So, the guy broke it off 1 mile out...I concur that is too tight. I do still stand by my 'gross deviation from really fundamental fundamentals'...So, maybe it's 1) Don't bank the hell out of a jet (especially down low), and 2) Fast planes will get ahead of you if you are behind. I can't totally discount the wind, but what...without the wind, they would have only needed an 85-degree bank?

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  • Evan
    replied
    Originally posted by elaw View Post
    Do you mean in the horizontal plane, or the vertical?
    What's the climbing radius of a Lear 35 in a 90* bank? I guess its an ever tightening... spiral...

    Leave a comment:


  • elaw
    replied
    Originally posted by Evan View Post
    What's the turning radius of a Lear 35 at approach speed in a 90* bank?
    Do you mean in the horizontal plane, or the vertical?

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  • Gabriel
    replied
    Originally posted by Evan View Post
    What's the turning radius of a Lear 35 at approach speed in a 90* bank?
    130 kts is 67 m/s.
    At 90 deg of bank you will not hold the altitude or attitude no matter how much you "pull up" (because "up" is 100% horizontal), but that doesn't prevent you from making the turn, and all the lift will contribute to the radial acceleration needed to bend the speed vector (i.e. turn).
    So let's say that you pull with a load factor of 2.5, that means that the lift will be 2.5 times the weight, and since the lift will be the only horizontal force with a radial component (neglecting an radial component that the thrust may have), we have

    Sum of F radial = 2.5 x weight = m x acc radial
    Since weight = m x g (g = acceleration of the gravity =~ 10 m/s2)
    2.5 x m x g = m x a
    So, a = 2.5 g = 25 m/s2

    Now, in a circular motion, a = V2/r, so r = V2/a = (67 m/s)2 / 25 m/s2 = 179 m = 0.1 NM

    How much with a 30 deg bank turn, assuming we hold the vertical speed constant?

    Well, the vertical component of the lift needs to be equal to the weight.
    The lift vector, tilted 30 degrees from the vertical, will need to measure weight / cos 30 deg.

    1/cos 30 = 1.15 will be the load factor (and, if you are interested, the stall speed will be sqrt(1.15) = 1.075 times, or 7.5% faster than, the 1G stall speed). But we are not interested in anything of this.

    The horizontal component of the lift, the one that will make the plane turn, will be lift x sin 30, and since lift was = weight / cos 30, we get that the horizontal component will be weight / cos 30 x sin 30 and that's weight x tan 30 = 0.58 times weight (and remember that weight = m x g).

    Horizontal force = horizontal component of the lift = 0.58 x m x g = m x a
    a = 0.58 g

    a = v2/r

    r = v2/a = (67 m/s)2 / 0.58x10 m/s2 = 773 m or 0.42 NM

    At 15 deg bank it would be 0.9 NM.

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  • Evan
    replied
    Originally posted by Gabriel View Post
    Orange and blue lines are 1 NM long. Green turns are 1NM radius. It assumes no wind.
    Typical descent path is about 300 to 350 ft per NM.
    With a plane that approaches at more than 100 kts, there's no way I am braking off the LOC 06 any closer than 4NM.
    [ATTACH=CONFIG]7746[/ATTACH]
    What's the turning radius of a Lear 35 at approach speed in a 90* bank?

    Leave a comment:


  • Gabriel
    replied
    Orange and blue lines are 1 NM long. Green turns are 1NM radius. It assumes no wind.
    Typical descent path is about 300 to 350 ft per NM.
    With a plane that approaches at more than 100 kts, there's no way I am braking off the LOC 06 any closer than 4NM.
    Click image for larger version

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  • Gabriel
    replied
    Originally posted by 3WE View Post
    Pure speculation- I think Gabe may be out of line that the turn needed to be 5 miles out...not sure that's Kosher in the New Yark crowded airspace with airports all over creation...BUT, indeed they waited too long...I was disappointed that Flying did not mention visibility or ceiling- as conceivably, that might force a guy to push it...delays in breaking out and seeing the airport and/or concerns with losing contact while 'circling'.
    What?

    The Runway 6 ILS, circle to Runway 1 is a common approach to TEB, with aircraft normally leaving the localizer at the final approach fix nearly four miles from the end of the runway. In the May 15 accident, the Learjet remained on the localizer until less than a mile from the end of Runway 6 before starting a right turn to land on Runway 1.
    At the time of the accident, winds were reported as 320 at 20 knots gusting to 30, a few scattered clouds at 4,500 feet and visibility of more than 10 miles.
    Guess where that comes from?

    Leave a comment:


  • 3WE
    replied
    Originally posted by Evan View Post
    I always thought a 'circle to land' needed a downwing leg.
    Indeed the term is inspired by a single-runway situation where you shoot the ILS, break out, and circle back around 180 degrees to land in the opposite direction (which actually is maybe more of a teardrop and not a circle)

    That said, with lots of runway configurations and the concept that you fly the ILS to get under the clouds and then land on a different runway results in the "circling minimums" that exist on typical approaches. http://155.178.201.160/d-tpp/1706/00890IL6.PDF

    Circle, teardrop, side-step, shuffle, and Lord knows what other gyrations might be used to land elsewhere...Yeah, it's insider jargon that conflicts with common, "Webster Dictionary" meanings, but is more efficient than "Maneuvering-for-another-runway minimums." Maybe you'd like 'MFARMS', better, but you may have to do more than post in this forum to get the industry to address it.

    So maybe break it off at 3 miles, then. Plus, I wonder if there might be issues with flying over the stadium?

    Leave a comment:


  • Evan
    replied
    Originally posted by 3WE View Post
    Pure speculation- I think Gabe may be out of line that the turn needed to be 5 miles out...not sure that's Kosher in the New Yark crowded airspace with airports all over creation...BUT, indeed they waited too long...I was disappointed that Flying did not mention visibility or ceiling- as conceivably, that might force a guy to push it...delays in breaking out and seeing the airport and/or concerns with losing contact while 'circling'.
    I always thought a 'circle to land' needed a downwing leg.

    Anyway...

    In a reasonably executed circle to land, I believe that Lear would need a circling radius of about 1.5 miles. Breaking off the ILS at 2 miles out, that seems unlikely to put you on the TDZ of RWY 1.

    Leave a comment:


  • 3WE
    replied
    Originally posted by Evan View Post
    Still, would that be considered a 'circle to land' approach? Seems more like... shuffle to land...
    http://155.178.201.160/d-tpp/1706/00890IL6.PDF

    Technicalities...when you land on a runway OTHER than the one the ILS is for, it is generally termed 'circle to land'....and generally, you can 'circle around' all over creation to whatever runway you need...I believe the major rule is to maintain visual contact with the airport, along with some basic altitude rules.

    Based on Gabe's flying article and the 'eyewitness accounts' of extreme banks, I now disagree with Gabe (that it's the ole subtle cramped turn to final with speed decay and visual speed misinterpretation), but more like gross deviation from the good FUNDAMENTAL practice of don't bank the hell out of the plane when down low (or if you are doing anything close to commercial flight).

    Sure, the winds may have contributed a bit, but if they were really banked as steep (or roughly as steep) as what the tower reported...someone had really bad tunnel vision, or were doing Evan's default of Cowboy disregard for fundamentals and procedure, both...

    Pure speculation- I think Gabe may be out of line that the turn needed to be 5 miles out...not sure that's Kosher in the New Yark crowded airspace with airports all over creation...BUT, indeed they waited too long...I was disappointed that Flying did not mention visibility or ceiling- as conceivably, that might force a guy to push it...delays in breaking out and seeing the airport and/or concerns with losing contact while 'circling'.

    Leave a comment:


  • Evan
    replied
    Originally posted by Gabriel View Post
    The tower does report a steep left bank and the nose going down, which would be compatible with a turn to final.
    The way I read that, the left bank was probably unintentional, the result of an asymmetric stall. I can't recall where the right turn was first stated as a turn to final (maybe that was your assumption?) but I tend to think the alleged stall happened when turning right, off the localizer... very late and very steep. I guess aerobatics, tailwind gusts and wingtip tanks don't mix.

    Still, would that be considered a 'circle to land' approach? Seems more like... shuffle to land...

    Leave a comment:


  • Gabriel
    replied
    Originally posted by Evan View Post
    Can you shed some light on how this circle to land is done here from the RWY 06 ILS? The only ILS 06 to visual 01 approach I can find involves breaking off the ILS in a right bank and then turning LEFT to final over Giant's Stadium. But, if I'm getting this right, the Lear was making a hard RIGHT turn to final when it lost control. Does that involve breaking off ILS and cycling right turns back to 01? That seems illogical to me.
    Yes, the normal and logical circling from 06 to 01 seems to be first right and then left. But that should be started at 5 miles out, not 0.5 miles out. Starting the circling so short would require much more significant turns (in the same directions as said before). Maybe the stall happened during the first right turn. I initially thought that they overshot the runway during the left turn so they had to ter left more than the RWY heading to come back and then make a right turn to align, but it seems that the accident happened much earlier in the process. The tower does report a steep left bank and the nose going down, which would be compatible with a turn to final.

    In any event, it still seems to be a garden variety of stall-spin-crash-burn-die while maneuvering in the pattern (or in the circling in this case).

    Leave a comment:


  • Evan
    replied
    Originally posted by Gabriel View Post
    Can you shed some light on how this circle to land is done here from the RWY 06 ILS? The only ILS 06 to visual 01 approach I can find involves breaking off the ILS in a right bank and then turning LEFT to final over Giant's Stadium. But, if I'm getting this right, the Lear was making a hard RIGHT turn to final when it lost control. Does that involve breaking off ILS and cycling right turns back to 01? That seems illogical to me.

    Leave a comment:


  • Gabriel
    replied
    Originally posted by Evan View Post
    You have a track on this one?
    No, but...

    The facts of the report show New York Approach Control cleared the aircraft for the ILS Runway 6, circle to land Runway 1, with strong northwesterly winds translating into a slight tailwind component as the aircraft tracked inbound on the localizer.
    The Runway 6 ILS, circle to Runway 1 is a common approach to TEB, with aircraft normally leaving the localizer at the final approach fix nearly four miles from the end of the runway. In the May 15 accident, the Learjet remained on the localizer until less than a mile from the end of Runway 6 before starting a right turn to land on Runway 1. That would have potentially placed the aircraft less than 500 feet above the ground. Leaving the localizer so near the airport would have also required a tight turn, close to the ground just to reach the numbers of Runway 1.
    As the Learjet began its right turn toward the landing runway, the full force of the wind now at its tail, would have increased its ground speed, pushing the aircraft toward the landing runway even faster. A turn of at least 130 degrees would have been necessary to give the pilot much of a chance for a smooth turn back to final. But with the strong tailwind, everything would have been happening very fast.
    What we don’t know is how far south the Lear flew before it began the turn back to Runway 1. According to the NTSB report, a TEB Tower controller did report the airplane banked hard to the right in the turn south and that he could see the belly of the airplane with the wings almost perpendicular to the ground. The airplane then appeared to level out for a second or two before the left wing dropped, showing the entire top of the airplane. Other ground witnesses reported the airplane in a right turn with the wings in a high angle of bank, some noting the airplane's wings "wobbling" before the left wing dropped and the airplane descended to the ground.
    http://www.flyingmag.com/teterboro-w...A0NDAzNDgwMQS2

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  • 3WE
    replied
    Originally posted by Gabriel View Post
    This smells like your typical Piper PA-11 flying-club-class turn-to-final stall when tightening the turn because you are overshooting the extended centerline, especially if you come with a tailwind component in the base leg.
    Failure to:

    -Monitor/maintain healthy airspeed.
    -Recognize a moderately-relentless pull up
    -Recognize the pattern of a steep, low altitude, low energy turn (and the 'synergy' of a crosswind requiring a tighter turn...)

    Again?

    (I know- AND am reminded that it might not be as obvious in a big, comfortable airplane versus cheap aluminum single engine crackerboxes).

    Leave a comment:

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