The so-called “impossible turn” is a concerning scenario for pilots of small fixed-wing aircraft. But what exactly is this maneuver and why is it considered so dangerous? In short, the impossible turn refers to an attempt to turn back to the departure runway after an engine failure immediately after takeoff.
Table of Contents
Key Points
- The impossible turn is an attempted 180 degree turn back to the runway after an engine failure.
- It is very dangerous due to low altitude, speed, and distance from the runway.
- Pilots should instead focus on managing the aircraft and planning an emergency landing.
- Proper preflight planning, aircraft control, and emergency training reduce risks.
It was a clear morning when pilot David took off from Runway 18, looking forward to a smooth flight. Seconds after rotation, however, the engine sputtered and fell silent. Fighting panic, he eyed the runway rapidly slipping behind him. Should he risk the “impossible turn”—a 180 back to the airport? Or trust his training and land straight ahead?
David’s dilemma highlights the feared impossible turn scenario feared by pilots. This desperate maneuver, turning back to the runway after a takeoff engine failure, tempts many aviators. Yet attempting it close to the ground is akin to a high stakes game of chance. So what transforms this enticing 180 into a potentially deadly trap? Read on to explore the illusions and realities around mastering the impossible turn. While the odds favor the house, understanding the risks and respecting your aircraft’s limits helps stack the deck in your favor.
The impossible turn is a daunting situation feared by pilots. Let’s explore the origins and realities around the impossible turn.
The Scenario Behind the Impossible Turn
The impossible turn refers to an attempted 180 degree turn back to the departure runway following an engine failure right after takeoff. This emergency maneuver is considered “impossible” for several reasons:
- The aircraft has low altitude with little margin for error, often below 1,000 feet.
- Airspeed is slow, typically below best glide speed, reducing controllability.
- The plane is close to the runway which requires a very steep bank angle of 45 degrees or more to turn back.
- The distance required for the 180 degree turn and return may exceed the aircraft’s glide range capability.
While the term suggests the turn cannot be completed successfully, the main issue is it involves considerable risks and challenges.
The extremely low altitude and lack of speed significantly hamper a pilot’s ability to maintain adequate control and properly execute the turn.
Dangers and Risks That Make the Maneuver So Hazardous
Many interconnecting factors combine to make the impossible turn an extremely hazardous maneuver with high risk. These include:
Insufficient Airspeed and Low Altitude
Right after takeoff, the plane will be slow, often below best glide speed, and close to the ground at a low altitude. This leaves almost no margin for error and greatly reduces options if loss of control occurs. There may be insufficient speed to recover from or even avoid a stalled condition.
Very Steep Bank Angle Required
The tight radius turn demanded to reverse course back 180 degrees to the runway usually requires an aggressive 45 degree or steeper bank. This significantly elevates the stall risk and potential for an uncontrolled departure or spin.
Close Proximity to Runway
If the turn is initiated too soon after takeoff, the aircraft may still be too close to the runway, sometimes within 1,000 feet or less. This further increases the already steep bank angle required, exacerbating aircraft control issues.
Potential to Exceed Aircraft’s Limits
Attempting the very sharp low-altitude turn may exceed the aircraft’s structural and performance capabilities. Stalling speed is increased significantly in the steeply banked turn, while options for recovery are extremely limited at low altitude.
High Rate of Descent
After the engine failure, the aircraft has lost its primary means of thrust and lift production. The descent rate rapidly increases to 700-800 feet per minute or more. This high rate of descent becomes critical when already operating at low altitude.
Increased Workload and Distraction
The emergency situation leads to increased pilot workload and distraction at the same time aircraft control is most critical. The cockpit becomes chaotic just when focus should be on flying the airplane.
Real-World Attempts Show the Extreme Risks
Actual attempts at the impossible turn have demonstrated just how dangerous and difficult it can be, even for experienced pilots. In one real-world example, the pilot climbed to 500 feet, then simulated an engine failure.
Despite being well prepared for the maneuver, the turn had to be aborted due to insufficient altitude. Descending at 700-800 feet per minute, there was no chance of completing the turn back to the runway.
This highlights that even in ideal conditions, the impossible turn poses major risks. The pilot was unable to revert course back to the runway from just 500 feet up. Factors like the steep bank angle required, lift reduction, and high descent rate made the turn truly impossible.
In another instance, a pilot climbed to only 300 feet before the simulated engine failure. Attempting the exceptionally sharp turn back to the runway, the aircraft was dangerously low and slow. The pilot wisely discontinued the maneuver to avoid a catastrophic crash short of the runway.
These real-world examples reinforce why standard training emphasizes always avoiding the impossible turn when below 1,000 feet AGL during takeoff or departure. The physics and aircraft capabilities mean the risks often far outweigh the potential benefits.
Why the Impossible Turn is Strongly Inadvisable
Rather than attempting the extremely low-altitude 180 degree turn, pilots are advised to continue straight ahead while managing the aircraft. Reasons to avoid the impossible turn include:
- Prioritizing aircraft control and flying within remaining capabilities by avoiding stalls, spins, or other loss of control.
- Climbing to a safe altitude above 1,500 feet AGL before attempting any turns back towards the airport. This provides critically needed options and margin for error if control issues arise.
- Identifying the most viable emergency landing site straight ahead. Scanning for open, flat fields absent of major obstacles.
- Focusing on planning and executing a controlled emergency landing in the landing site.
- Not risking a hazardous maneuver that may quickly lead to an unrecoverable stall or spin when performed at low altitudes.
While counterintuitive, pilots are repeatedly trained to resist the huge temptation to return to the runway. Their priorities are maintaining control, achieving a safe altitude, and landing in the most suitable area ahead.
Safer Alternatives to the Impossible Turn
To avoid the substantial risks of the impossible turn, pilot training emphasizes much safer options:
Maintain Aircraft Control
Keep flying the airplane within its normal flight envelope and capabilities. Don’t rush control inputs or exceed aircraft limitations. Avoid aggressive maneuvers, steep banks, stalls, or slow flight.
Climb Gradually to a Safe Altitude
Gently gain altitude to at least 1,500 feet AGL to allow more options. Don’t try to climb too rapidly or risk an accelerated stall. Level off and maintain altitude once sufficient height is reached.
Scan and Plan Emergency Landing Area
Thoroughly scan for the most viable emergency landing site ahead. Consider terrain, obstacles, wind direction, ground surface, and aircraft energy state.
Follow Emergency Checklists
Refer to emergency checklists to configure aircraft systems and communicate with air traffic control. Troubleshoot issues while maintaining control.
Declare Emergency with ATC
Notify air traffic control of the situation to receive priority handling and alert emergency responders. Follow ATC guidance and instructions.
Final Thoughts on the Impossible Turn
While dubbed “impossible,” attempting to turn back to the runway after takeoff engine failure is not automatically disastrous. But it does involve extremely serious risks that can quickly lead to loss of control and stall or spin situations.
By understanding the multitude of challenges involved, respecting the aircraft’s limitations, and focusing on maintaining control, pilots can often land safely without attempting the turn.
With proper emergency training and prevention of engine failures, the impossible turn will hopefully remain a very rare event. But if encountered, resisting that strong temptation to turn back is key to the best outcome.
As the ancient proverb says, “Good judgment comes from experience, and experience comes from bad judgment.” While the impossible turn may tempt aviators, don’t let it turn into a deadly judgment call. Respect the aircraft, trust your training, and take comfort that the safest 180 is sometimes just straight ahead.
