AOPA Pilot Magazine - April 2011 - 96

VISION
What’s waiting for you out there? Comprehensive in- ight weather data from XM WX Satellite Weather delivers the full scope of your surroundings with radar, lightning, winds aloft and more. Enjoy enhanced situational awareness and e ciency while you y. Make XM WX a permanent part of your cockpit. And never fly blind again.

AS VITAL AS

Following this accident, several experienced pilots told me about the golden rule. They admonished me for turning around and not landing straight ahead. There was something wrong with this conventional wisdom, I thought. Following their advice would have meant trying to thread my way to a crash landing in a congested residential neighborhood. I am convinced that the outcome would have been disastrous. This seminal event started me on what became a decades-long study of the options available to a pilot following an engine failure that occurs shortly after takeoff. I first wrote about this subject 37 years ago and have been developing ever since a number of thoughts about this subject that you might find worthy of consideration. The “impossible turn” When unprepared for such an engine failure, it generally is best to land straight ahead (or somewhat right or

the turnaround maneuver can be performed with relative safety. For starters, what bank angle should be used? Safety suggests a shallow bank angle. The problem is that a shallow, large-radius turn displaces the airplane so far from the extended runway centerline that a return to the runway becomes less likely. Although a very steep bank angle substantially reduces turn radius and keeps the airplane closer to the runway, the associated rise in stall speed is unacceptable. The optimum bank angle appears to be a compromise, 45 degrees. This prevents excessive lateral displacement from the extended runway centerline and results in only a 19-percent increase in stall speed (from 55 to 65 knots, for example). Interestingly, more altitude is lost during a shallow-banked gliding turn than during the same amount of turn using a steep bank. The explanation for this apparent paradox involves time.

The climb speed that typically places a pilot in the best position for turning around is halfway between VX and VY.
left of the runway’s extended centerline). NTSB records are replete with accidents resulting from pilots attempting to turn around and land from too low an altitude. The most common result of trying to avoid ground contact before completing the turn is a stall and/or a spin into oblivion. This is why a turn back to the runway is described by some as the “impossible turn,” a misleading description of what can be a life-saving maneuver. There are times when attempting to land straight ahead would be extremely hazardous and a less-desirable option. Records are not kept and do not reflect the many success stories of those who experienced an engine failure, turned around, and landed safely and without incident. Lacking aircraft damage or personal injury, there obviously is no reason to file an accident report. Video of one such event was posted on the Air Safety Institute’s website (http://flash.aopa.org/asf/pilotstories/ impossibleturn/). The difference between success and failure is not only having sufficient altitude, but knowing how and when
AOPA PILOT •

w w w. X M W X W E AT H E R . c o m 1-888-355-0132 8AM-5PM EST
Hardware and required monthly subscription sold separately. Subscription fee is consumer only. Other fees and taxes, including a one-time activation fee, may apply. All programming fees and weather data are subject to change. XM WX weather data displays and individual product availability vary by hardware equipment. Reception of the XM signal may vary depending on location. Subscriptions subject to Customer Agreement included with the XM Welcome Kit and available at xmradio.com and are available only in the 48 contiguous United States. XM WX is a trademark of XM WX Satellite Radio Inc. The XM WX service is not for “safety for life”, but is merely supplemental and advisory in nature, and therefore cannot be relied upon as safety-critical in connection with any aircraft or other usage. XM is not responsible for accidents resulting from or associated with use of the XM WX Service. Contact XM WX Satellite Radio by phone at 800.985.9200 to subscribe to XM WX Weather. ©2010

Although sink rate is greater when turning steeply, rate of turn is so much greater that less time is spent losing altitude than when turning with a shallow bank angle. Turn direction can be important, too. In the presence of a crosswind, turn into the crosswind (upwind) to prevent drifting away from the runway’s extended centerline. A turn away from the wind (downwind) can result in so much drift that returning to the runway might become impossible. If wind is not a consideration, then turn over the lowest obstacles that might be in the departure area. No obstacles and no wind? Turn left because most pilots are more comfortable turning that way. With respect to airspeed, use the airplane’s best glide speed to achieve maximum glide range and to provide a safe airspeed margin above stall. You certainly would not want to fly any faster than this because of the excessive sink rate and angle that would result. Although maintaining the best glide speed seems logical, David F. Rogers, a professor of aerospace engineering at the U.S. Naval Academy, calculated that the

96 • APRIL

2011

http://www.XMWXWEATHER.com http://www.XMWXWEATHER.com http://flash.aopa.org/asf/pilotstories/impossibleturn/ http://www.xmradio.com

AOPA Pilot Magazine - April 2011

Table of Contents for the Digital Edition of AOPA Pilot Magazine - April 2011