REFLECTOR: OT Plane hits an apartment building in NYC

Chuck Jensen cjensen at dts9000.com
Sun Oct 15 09:09:33 CDT 2006 

Emanuel,
You proved mathematically what I suspected intuitively.  Sometimes
mathematics and intuition coincide and sometimes not.  There may be a
lot of us (though hopefully not too many) that believe we could reverse
course in 2000' but how many have tried it when there are boundaries
both sides.  The NTSB reports for Colorado, Idaho, et al, indicates
there's a lot of pilots that think they can turn in less radius then
they are actually able.

A blog by a pilot named Greenspun who has flown this route in light
planes says that winds from the east, northeast often funnels between
buildings and can sometimes be twice the velocity of the reported
surface winds.  In a tailwind landing, we all know how uncomfortable a 5
kt tailwind makes us feel as it pushes us to the runway.  If the SR20
pilots had a 20-30 kt crosswind/tailwind as they reversed course, one
suspects that they had just barely started their turn, looked down and
saw that half the river was already gone by.  If they hadn't tried so
hard, they probably would have missed the building altogether....on the
far side.

Chuck Jensen
Do Not Archive

> -----Original Message-----
> From: reflector-bounces at tvbf.org 
> [mailto:reflector-bounces at tvbf.org] On Behalf Of Emanuel Lewis
> Sent: Saturday, October 14, 2006 9:20 PM
> To: Velocity Aircraft Owners and Builders list
> Subject: Re: REFLECTOR: OT Plane hits an apartment building in NYC
> 
> 
> Chuck:
> You made me go back to the drawing board to add the cross 
> wind component to 
> the equation.  The result is:
> r ~ v(0.09 * v + 0.28 * cross wind)/tan phi.
> So, at 100 kts, 45 degree bank angle, and a 20 kt cross wind 
> the radius is 
> 1320' or 2640' to make the turn, more than enough to hit a 
> building.  At 100 
> kts and 60 degrees with a 20 kt cross wind the radius is 776' 
> or about 1550' 
> to make the turn which would just make it if they started out 
> hugging the 
> shoreline.
> It looks like they got into a situation over their head caused by a 
> combination of poor planning and piloting skills below what 
> the situation 
> required.
> Manny Lewis
> ----- Original Message ----- 
> From: "Chuck Jensen" <cjensen at dts9000.com>
> To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
> Sent: Saturday, October 14, 2006 2:35 PM
> Subject: Re: REFLECTOR: OT Plane hits an apartment building in NYC
> 
> 
> > Emanuel, as you were alluding to, even if they were doing twice a 
> > standard rate turn, it would still take them 30 seconds to reverse 
> > course.  A 20kt crosswind has a velocity of 34 fps.  In 30 seconds, 
> > the wind will have pushed the plane half way across the 
> river, so now 
> > they must reverse course in 1/2 the width of the river.  And of 
> > course, if they didn't 'hug' the right side of the river before 
> > starting the turn, they would have <2000' to work with.  In 
> addition, 
> > they were probably half way through the turn before it 
> became apparent 
> > that they were in trouble and tried to crank it in tighter; 
> > potentially resulting in an accelerated stall, explaining the 
> > 'aerobatics' that were observed.
> >
> > In highly technical statistical terms, the odds of 
> successfully making 
> > that course reversal for the average pilot, could be 
> characterized as 
> > 'fat chance.'  About the same chance as John Jr. making the 
> over water 
> > flight at night in poor visibility.  It can be done, but 
> the odds are 
> > tilted the wrong way.
> >
> > Chuck Jensen
> > Do Not Archive
> >
> >
> >
> >> -----Original Message-----
> >> From: reflector-bounces at tvbf.org 
> [mailto:reflector-bounces at tvbf.org] 
> >> On Behalf Of Emanuel Lewis
> >> Sent: Saturday, October 14, 2006 1:34 PM
> >> To: Velocity Aircraft Owners and Builders list
> >> Subject: Re: REFLECTOR: OT Plane hits an apartment building in NYC
> >>
> >>
> >> The turning radius is not a function of the aircraft, per 
> se, it is a 
> >> function of the aircraft's TAS and bank angle.  For those 
> >> mathematically
> >> inclined:
> >> r(ft)~v squared (kts) / 11.26 tan (phi), where phi is the 
> bank angle. 
> >> At a 45 degree bank angle 100 kts will give you a radius of about 
> >> 900', at 150 kts the radius goes up to about 2000'.
> >> The width of the East River is about 1600', so we are talking
> >> about an 800'
> >> radius.  To have an 800' turning radius at 100 kts you need a
> >> bank angle of
> >> about 52 degrees, at 150 kts the bank angle would have to 
> be about 67
> >> degrees.  There was a 15 - 25 kt wind out of the east to add
> >> to the problem. I have flown the corridor in my Velocity.
> >> You fly to the right of the
> >> centerline of the river (either Hudson or East) and make your
> >> turns to the
> >> left to reverse course.
> >> Need I say more.
> >> Manny Lewis
> >> CFI/II
> >>
> >> ----- Original Message -----
> >> From: "John Dibble" <aminetech at bluefrog.com>
> >> To: "Velocity Aircraft Owners and Builders list" 
> <reflector at tvbf.org>
> >> Sent: Friday, October 13, 2006 10:40 AM
> >> Subject: Re: REFLECTOR: OT Plane hits an apartment building in NYC
> >>
> >>
> >> > This is starting to make some sense, but the instructor 
> should have 
> >> > been able to make the required steep U-turn.  Wonder if they
> >> forgot about the
> >> > reg that says you
> >> > can violate any regulation (ie B airspace) if deemed
> >> necessary for safety.
> >> > Is there any data on the turning diameter for a Velocity as
> >> a function of
> >> > bank angle/speed?
> >> >
> >> > John
> >> >
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