THE IMPOSSIBLE TURN
In May 1992 at Tumbler Ridge, B.C., a Piper Cherokee aircraft with five passengers crashed following an attempt by the pilot to return to the runway after experiencing an engine failure. The aircraft was only 100 feet above the ground when the engine problem occurred. The aircraft stalled during the attempted turn, causing loss of control at an altitude from which recovery was impossible.
This was not an isolated incident. During a 10-year period from 1982 to 1991, there were 176 accidents resulting from engine failure after take-off in single-engine aircraft. In about half of these, the pilot tried to turn back to the departure runway instead of landing straight ahead. In most of these accidents, the pilot lost aircraft control while attempting the impossible return to the runway.
An analysis of these accidents showed that an aircraft crash caused by loss of control as a result of excessive manoeuvring is 10 times more likely to cause fatalities, and five times more likely to cause serious injuries than if the pilot had elected to land straight ahead. Lower groundspeed associated with a straight-ahead into-wind forced landing, as well as being under control prior to impact with the terrain, reduces the risk. Surprisingly, the data also revealed that experienced pilots are just as likely as novices to attempt the impossible.
Using data from the Cessna 172 Aircraft Flight Manual, our test pilots crunched some numbers to help convince you that straight ahead and under control is your only real option.
Using the following conditions, the analysis was done for an engine failure at 500 ft and 1000 ft.
Conditions and Assumptions
Altitude - Sea level
Temperature - ISA
Wind - Calm
Climb speed - 75 kts IAS
Rate of climb to 500' - 688 ft/min
Rate of climb to 1000' - 675 ft/min
Glide speed after engine failure - 65 kts IAS
Glide performance - 1.5 nm/1000'
Bank angle in turn back - 30 degrees
The analysis assumes a straight climb-out followed by a 270 degree turn, a reversed 90 degree turn and a straight return to the runway. It also assumed that the climb starts at the end of the runway at 50 ft and at the specified climb speed. Flap extension for landing was not considered.
Results
Failure at 500'
Failure at 1000'
Time to climb
39 secs
84 secs Distance covered
4,937 ft
10,634 ft Radius of turn
648 ft
648 ft Return distance covered during turns
1,296 ft
1,296 ft Distance remaining to runway
3,641 ft
9,338 ft Total distance from failure back to runway
7,711 ft
13,408 ft Glide capability after engine failure
4,560 ft
9,120 ft
The analysis shows that from 500 ft a turn back would result in landing 3150 ft short of the runway, and from 1000 ft the landing would be 4300 ft short.
You can argue that a tighter turn reduces the distance back, but it also increases the load factor and therefore degrades glide performance, gaining you no advantage.
If a 10-knot headwind is considered and the numbers recrunched, the results show that the landing would still be 1840 ft short of the runway and 1460 ft short for the 1000 ft case.
The calculations indicate that given sufficient wind a return to the field may be theoretically possible, but the hazards of a downwind landing in such strong wind would not make this advisable, specially if one considers the very low groundspeed expected during a forced landing directly into a strong wind.
In summary, for a single-engine aircraft, given reasonable wind conditions, it is not possible to return to the take-off runway following an engine failure. Straight ahead and into wind is the only option.
