Tuesday, July 20, 2010

Amy Arrow and Never Again

Oshkosh preparations have been running us 7/24.  We've been preparing 3 ships for Oshkosh Airventure; on top of that we just completed a customer delivery and we have another which we won't get done before Osh.  (But we wanted to.)  And on top of all that is our 'secret ops' which are preparing some major whammy to talk about at Osh.

But never mind that.  Time to write a blog post...

Please back up about 15 years in my life....  to a memory from my past.

I was heading to Denver, Colorado to attend a "Promise Keeper" event.  I had arranged to rent a retractable Piper Arrow, which boasted a 180HP engine, good range, and a useful load of about 850 pounds.  The owner of the airplane affectionately called her 'Amy Arrow'.

It was hot in the summertime; we landed at Centennial airport without issues.  The Promise Keepers event was soon over, and we headed back to Centennial for the flight home. I had myself and 2 friends on board, (or, as I liked to say when I filed a flight plan, 3 souls on board).  

I had filled the tanks for the flight home.  I had also carefully reviewed the flight manual:  the flight manual called for 25 degrees of flaps in order to produce a short ground roll.  I dialed in 25 degrees, per the manual.  (Very stupid... as you shall soon see.)  Our plane was exactly at gross weight.  Density altitude was somewhere around 8500+ feet.  That shouldn't be a problem with an airplane that had a service ceiling well over 13,000 feet...   right?!

We were cleared for takeoff at Centennial.

I advanced the throttle, and Amy Arrow started to move down the runway.  Slowly.

Somewhere around 3 or 4 thousand feet down the runway, I started to pull back on the elevator.  Amy dutifully rose about 8 feet above the ground.

And stayed there.  5000 feet of runway remaining.

And stayed there.  4000 feet of runway remaining.

And stayed there.  3000 feet of runway remaining.

And stayed there.  2000 feet of runway remaining.

And stayed there.  Still 8 feet off the ground, 1000 feet of runway remaining.

I refused to set it back down and abort the takeoff.  Why?  More youthful piloting stupidity.

I saw a ridgeline off in the distance, straight ahead.  That was a problem.  I would hit it.

I saw a descending valley off to the left.  If I turned that way, I would have terrain descend, thus improving my relative altitude to the ground.

I slightly turned to the left.

I realized I was hovering over the ground... the plane would not climb.  I had two opportunities to reduce drag:  Get the gear up.  Reduce flaps.  I also realized that if I rapidly retracted flaps, the plane would immediately settle to the ground.  First things first... I retracted the landing gear.

Then, I grabbed the manual flap handle, and   s l o w l y  went from 25 degrees, to 20, then to 15, then to 10 degrees of flaps, then to five, then to zero.   The plane seemed to stop mushing over the ground.

We flew over a golf course.  Since the terrain was descending, and we were now probably climbing at 50 feet per minute, we had perhaps 150 feet of altitude over the course.  Some golfers looked up at this strange sight of an airplane, so close to the ground, passing over to them.

And then I realized that the plane had perhaps 250 feet of the ground, and that positive climb was definitely occurring.  We would be okay.

And then I realized something else was occuring:  the tower at Centennial was talking to me.  I hadn't heard them, because the crisis had shut down that part of the brain that listens to outside voices.

"are you OK....   are you OK...   are you OK..."  I could also hear our N number, recited over and over.

"Yes, I'm OK".

They couldn't see me:  my plane had turned left and disappeared below their horizon.

I soon cancelled flight following and headed home for Wichita.  I kept wondering what my passengers were thinking:  had I just nearly killed them?

Here is my list of stupidities:

  A)  Dialing in 25 degrees of flaps is great for reducing ground roll, but does not improve Vy.  In fact, it has the opposite effect.  You can't climb with 25 degrees of flaps in a 180HP Piper Arrow.

  B)  Density altitude is a killer.  A non-turboed Arrow is a horrible climber in high DAs.

  C)  Flying at gross weight in high DAs is also a killer.

  D)  Lean the engine!  

  E)  And most importantly:  aborting the takeoff.  I had multiple opportunities to abort and I did not do so.

As Flying magazine says, Never Again.



xaminmo said...

This reminds me a bit of a takeoff I had about 3 months ago. I'd been out of the saddle for a while, and hadn't flown Pipers much. Most of my time had been in a DA40 which has a lot of lift and great low-speed handling.

So, I was with a CFI with literally tens of thousands of hours, in his plane, a Cherokee 140. Nice plane, and he's very familiar with it.

But I'm deceptively heavy. I'm 6'6 and about 285 out of the shower. Throw on clothes and a tiny flight bag, and we're around 300lbs just for me.

So we landed on a 3000' grass strip with high humidity, then backtaxied for takeoff. We didn't calculate anything. To this day, I don't know the BEW of that plane. I became complacent because of the CFI's experience.

My SWAG is that DA was probably around 3200'. The CFI is about 150 and I'm about 300. We'd only burned about 45 mins of fuel, pretty well leaned, so while not full tanks, they were full enough.

Well, to backtaxi took at least 50% throttle. That should have been an indicator. I gave us as much length as I could. I don't think I did any sort of short field effort, but I could feel the drag with the elevator full up.

As the nose came up, I began easing out backpressure to keep the nose wheel just barely above the grass. We were half way down the field before we made it into ground effect.

At that point, we were really committed to take-off, because there are trees about 350' from the runway end.

But, just as the 181 wouldn't climb much in those conditions, the 140 also wouldn't climb much. I had to keep it relatively level to let her accelerate and there wasn't enough room to try milking off the flaps. Plus, if I dropped the bar, that'd be a huge loss of lift.

We cleared the trees by maybe 150', which is not enough for me. The CFI was getting nervous for the last 700' or so. It was the second time he seemed confused by how the plane was behaving, and I think he just hasn't flown with this much mass in that bricky of a plane in a while.

But, I was PIC. He was there for orientation and assist. I allowed his comfort with the plane to lull me into not calculating W&B for any flights in that plane. I know I was "within limits" but I don't know how far from the margins I was, and therefore couldn't have put in any sort of personal minimums.

For me, at my experience level, anything less than 200% rwy required means I need to be really familiar with the runway, the plane, and be pretty current. In retrospect, I think we were probably at 150%, and I wasn't at 100%, which made things uncomfortable.

Since then, I've picked up a small hang-scale that's light and portable (for bags) and I'm going to pick up an easier to use W&B calculator for my cellphone so I can do calculations and get perf data quickly enough to not feel pressured or rushed by my own time worries.

xaminmo said...
This comment has been removed by the author.
James Wiebe said...

I finally recalled the N number of the aircraft in question... N4634J. I did some web searching for it... and found it on the NTSB accident database.