The March 2021 crash of a Beechcraft Bonanza A36 in Pembroke Pines, Florida, resurfaced
debate about the “turnback,” or the “impossible turn”, an engine-out course reversal shortly
after takeoff to land in the opposite direction on the departing runway.
Initial NTSB reports indicate the pilot of the Bonanza attempted a turnback with disastrous
results.
Opponents of the turnback argue that it’s impossible in some aircraft, and near impossible
in the rest.
Even with a glide ratio that makes a turnback technically possible, they say, the difficulty
of the maneuver, close proximity to the ground, a startle factor, and the stress of life-or-death
consequences all conspire against a successful outcome.
Proponents argue that turnbacks are a viable option for some pilots, in some aircraft,
under some circumstances.
As for the FAA, they caution that CFIs should train single-engine pilots not to attempt
a turnback unless altitude, best glide performance and pilot skill allow for a safe return.
In April, the AOPA Air Safety Institute flew test profiles in several aircraft to determine
the feasibility of the so-called “impossible turn.”
We flew turnback profiles at Martinsburg, West Virginia’s 8,800-foot-long, 150-foot-wide
runway.
Our lineup included me in my 150-horsepower, 1993 Piper PA–18 Super Cub with full gas;
Editor-at-Large Dave Hirschman flew solo in his Van’s RV–4 fully fueled; AOPA Director
of Flight Operations Luz Beattie alone in a fully fueled 1978 Cessna 172N; and Hirschman
and AOPA Vice President of Flight Operations Dave Roy in a 1971 Beechcraft Bonanza A36
with a 300-horsepower Continental IO-550, full gas, and 40 pounds of baggage.
Prior to the exercise, we all climbed to altitude and practiced stalls, including stalls in
45 degrees of bank, to calibrate the actual stall speeds at play during our turnback exercise.
We then established our minimum required turnback altitudes using a technique inspired by airline
pilot and CFI Brian Schiff.
We set a climb profile, cut the power to idle, and began an idle power, 45-degree-bank turn
at best glide for 360 degrees, noting the altitude lost.
The idea behind using a 360 degree turn is that practicing at 180 degrees is not enough.
The 180 degrees will get you turned around, but abeam the runway.
In reality, it takes more turn to get back over to the runway and aligned with the runway
centerline.
With stall numbers and expected turnback altitude requirements freshly established, we each
flew three profiles in near-perfect conditions: cool, sunny morning, light winds, and low
density altitude, on a simulated 4,000-foot-long runway.
The plan was to climb between VX and VY with full power to the predetermined altitude,
cut power to idle, delay three seconds to simulate a startle period, then push to best
glide while entering a 45-degree-bank turn back to the runway.
I went first in the Super Cub.
The
Super Cub returned to a simulated 4,000-foot-long runway in all three turnback attempts, one
at 500 feet AGL and two at 300 feet AGL.
In fact, I estimate I could have returned back to a 2,000-foot-long runway in the Super
Cub.
Next up - Dave Hirschman in his RV-4.
Hirschman initiated turnbacks at 1,000 feet AGL.
He made it back, barely, two out of three times.
The third time would have resulted in a landing short of the runway.
Hirschman’s performance may have been impacted by his three-blade, constant-speed propeller
that created far more drag at high-RPM setting than a fixed-pitch prop would.
Luz Beattie made her turnbacks at 1,000 feet AGL, 800 feet AGL, and 600 feet AGL.
She comfortably returned to the runway each time.
Both Beattie and I may have benefited from some idle thrust, with engines still running,
but experts such as Catherine Cavagnaro advised us that the light thrust we might have received
at idle power was somewhat offset by the drag from the moving propeller, so the advantages
of an engine at idle are believed to be minimal.
The last airplane to try the turnback profile was the Bonanza.
And those results were perhaps the most startling.
Turning back at 1,000 feet AGL and varying speeds from best glide (110 knots) to 95 knots
(to reduce the turn radius), and propeller settings from high to low RPM, Dave Roy and
Hirschman didn’t come close to making it back to the runway
in any attempt.
Even in an optimum glide configuration with landing gear and flaps up, the Bonanza would
have come down well short of a simulated 4,000-foot-long runway.
Our takeaway is that turning back is a viable option for certain aircraft, in the right
conditions, flown by proficient pilots who have trained for the maneuver.
It's not a good option for aircraft with high climb speed and high best glide speed, as
we learned with the Bonanza.
These speeds combine to take you farther from the runway on departure, and result in more
offset in the turnback, leaving you longer distance to glide.
Pilots flying aircraft with these characteristics should eliminate turnbacks as an option for
engine failure after takeoff.
Variables like wind, temperature, density altitude, runway length, and technique could
affect these results, but not enough to change our overall recommendations.
Please don’t try to fly this exercise solo in an attempt to prove us wrong or confirm
our results.
We’ve lost pilots training in these maneuvers due to the high potential for an uncoordinated
stall and spin in the turnback.
Fly with a CFI, at altitude first, and determine your strategy in the event of an engine failure
on takeoff.