Branchoria UFOs and UAP by State UFOs and UAP by State

Compare sightings, records, and explanations across U.S. states.

Within Helicopter Case

What Caused the Mansfield Helicopter's Sudden Climb?

The reported 1,800-foot rise is the case's strongest anomaly, but it rests on cockpit readings and recollection rather than recorded flight data.

27 sources 3 graphics

On this page

  • What the crew said the controls were doing
  • How the altitude gain was reconstructed
  • Why the missing flight data prevents a firm conclusion
Preview for What Caused the Mansfield Helicopter's Sudden Climb?

Introduction

The most striking claim in the 1973 Mansfield helicopter encounter is not that the crew saw an unusual light. It is that their UH-1H helicopter reportedly climbed about 1,800 feet while the pilot believed he was still trying to descend. If true, that would represent an unusual and potentially dangerous departure from normal aircraft behaviour. Yet the evidence for the climb comes almost entirely from witness testimony and cockpit instrument readings remembered after the event. No flight recorder, radar track, or independent altitude record survives to verify exactly what happened.[Center for UFO Studies]cufos.orgA Helicopter UFO Encounter Over OhioCenter for UFO StudiesA Helicopter-UFO Encounter over OhioOctober 30, 2023 — by J Zeidman · Cited by 4 — The encounter between a military…Published: October 30, 2023

Uncommanded Climb illustration 1

For that reason, the reported altitude gain remains one of the strongest and most disputed elements of the Mansfield case. Supporters regard it as evidence that something affected the helicopter itself. Sceptics argue that a combination of pilot workload, night-flying conditions, instrument scanning gaps, and human perception could explain the apparent anomaly. More than fifty years later, the question is still not whether the crew saw a light, but whether the helicopter genuinely climbed uncommanded.

What the Crew Said the Controls Were Doing

According to Captain Lawrence Coyne’s account, the helicopter was descending to avoid what appeared to be a rapidly approaching object. He later reported that the aircraft had been placed into a significant descent, with power reduced and the controls set in a manner inconsistent with a climb. When he next checked the instruments after the encounter, he found the helicopter at roughly 3,500 feet and still climbing at around 1,000 feet per minute. The altitude he remembered seeing before the encounter was about 1,700 feet.[Center for UFO Studies]cufos.orgA Helicopter UFO Encounter Over OhioCenter for UFO StudiesA Helicopter-UFO Encounter over OhioOctober 30, 2023 — by J Zeidman · Cited by 4 — The encounter between a military…Published: October 30, 2023

In later retellings, Coyne maintained that he had not intentionally pulled the aircraft into a climb. Some versions of the story also state that the collective pitch control remained lowered while the helicopter was gaining altitude. If accurate, that detail would be difficult to reconcile with normal helicopter operation because the collective is the primary control used to increase lift.[uapglobe.com]uapglobe.comcoyne helicopter 1973Radio contact returned only after the object was gone. The magnetic compass never worked…Read more…

The other crew members generally supported the claim that the aircraft’s altitude increased unexpectedly. Their testimony helped make the case notable within Ohio UFO history because the reported climb was not based on a single witness’s recollection. Nevertheless, none of the crew could provide an independent recording showing exactly how the controls were positioned throughout the event. The evidence therefore depends on memory rather than preserved flight data.[Center for UFO Studies]cufos.orgA Helicopter UFO Encounter Over OhioCenter for UFO StudiesA Helicopter-UFO Encounter over OhioOctober 30, 2023 — by J Zeidman · Cited by 4 — The encounter between a military…Published: October 30, 2023

8:30

1973 Mansfield Ohio UFO Encounter

Channel: Missing Information · Views: 448 · Uploaded: November 2021 · Length: 8 minutes

Open on YouTube

How the Altitude Gain Was Reconstructed

A key point often overlooked in popular summaries is that the 1,800-foot figure was reconstructed after the fact. The crew did not possess a flight data recorder that continuously logged altitude, airspeed, power settings, or control inputs. Instead, the climb was inferred by comparing remembered instrument readings before and after the encounter.[Center for UFO Studies]cufos.orgA Helicopter UFO Encounter Over OhioCenter for UFO StudiesA Helicopter-UFO Encounter over OhioOctober 30, 2023 — by J Zeidman · Cited by 4 — The encounter between a military…Published: October 30, 2023

The basic reconstruction runs as follows:

  • The helicopter was cruising near 2,500 feet above mean sea level.
  • Coyne began a descent to avoid the incoming light.
  • He recalled seeing approximately 1,700 feet during the descent.
  • After the object departed, the altimeter reportedly showed about 3,500 feet.
  • The vertical-speed indicator indicated a continuing climb.[cufos.org]cufos.orgA Helicopter UFO Encounter Over OhioCenter for UFO StudiesA Helicopter-UFO Encounter over OhioOctober 30, 2023 — by J Zeidman · Cited by 4 — The encounter between a military…Published: October 30, 2023

Those figures produce the frequently quoted gain of roughly 1,800 feet. However, because the numbers come from observations made during a stressful, rapidly evolving situation at night, there is no way to know their exact precision. Even advocates of the case acknowledge that the altitude change was not captured by independent instrumentation.[Center for UFO Studies]cufos.orgA Helicopter UFO Encounter Over OhioCenter for UFO StudiesA Helicopter-UFO Encounter over OhioOctober 30, 2023 — by J Zeidman · Cited by 4 — The encounter between a military…Published: October 30, 2023

This distinction matters. The climb is not a measured event preserved in a data archive. It is a reconstruction based on what experienced aviators believed they saw on their instruments during an unusual encounter.

Uncommanded Climb illustration 2

Could a Helicopter Climb Without a Deliberate Command?

The answer depends on what is meant by “without a command”.

A helicopter can gain altitude without the pilot consciously deciding to climb. Factors such as control pressures, trim changes, turbulence, distraction, or instinctive control movements can alter the aircraft’s flight path. Pilots under stress may make small inputs without fully registering them, especially during a perceived collision threat.[kevinrandle.blogspot.com]kevinrandle.blogspot.comit the helicopter was due to the unconscious, instinctiveA Different Perspective: The Coyne Helicopter Case24 Apr 2025 — It is a detailed examination of the case that includes the skeptical argu…

Sceptical investigator Philip J. Klass argued that the Mansfield climb was probably not a genuine violation of helicopter performance. He suggested that the crew’s attention was focused on an unusual light and that instinctive reactions or misperceptions could account for the apparent altitude change. Later discussions of the case have continued to highlight the possibility of unconscious pilot inputs during a high-workload situation.[Medium]ryan-sprague51.medium.comThe Coyne Helicopter UFO Incident | by Ryan Sprague | MediumKlass, a noted UFO skeptic, proposed that the crew had actually misidentified a meteor, suggesting that the green light was a result…

Supporters of the encounter respond that Coyne was an experienced pilot and repeatedly insisted that the aircraft’s configuration should not have produced a climb. They argue that the combination of altitude gain, unusual lighting effects, and reports of instrument irregularities makes a simple pilot-error explanation unsatisfactory.[Center for UFO Studies]cufos.orgA Helicopter UFO Encounter Over OhioCenter for UFO StudiesA Helicopter-UFO Encounter over OhioOctober 30, 2023 — by J Zeidman · Cited by 4 — The encounter between a military…Published: October 30, 2023

The difficulty is that neither position can be tested directly. The relevant flight parameters were never recorded.

14:34

Lt Coyne UFO case 1973 Mansfield Ohio

Channel: GFAM Media · Views: 335 · Uploaded: July 2022 · Length: 14 minutes

Open on YouTube

Why the Missing Flight Data Prevents a Firm Conclusion

The absence of objective flight records is the central weakness in any attempt to determine whether the climb was real, exaggerated, or misunderstood.

No known evidence includes:

  • Flight-recorder data.
  • Radar-derived altitude measurements.
  • Air-traffic-control tracking confirming the climb.
  • Independent telemetry from the helicopter.
  • Photographic or video documentation of the event.[Center for UFO Studies]cufos.orgA Helicopter UFO Encounter Over OhioCenter for UFO StudiesA Helicopter-UFO Encounter over OhioOctober 30, 2023 — by J Zeidman · Cited by 4 — The encounter between a military…Published: October 30, 2023

As a result, investigators must rely on testimony. Witness testimony is important, especially when it comes from trained military personnel, but it is not the same as instrumented evidence. Aviation accident investigations routinely place great weight on recorded flight data because even experienced crews can misremember timing, altitude, or control inputs during stressful events.

The Mansfield case therefore occupies an unusual middle ground. The witnesses were credible and consistent enough for the incident to remain one of Ohio’s best-known aviation-related UFO reports. At the same time, the strongest anomaly—the alleged uncommanded climb—cannot be independently verified.[ashlandsource.com]ashlandsource.comcoyne incident over charles mill lake was most credible ufo sighting of 1973Coyne Incident over Charles Mill Lake was most credible…4 Oct 2020 — The helicopter was cruising at 2,500 feet above sea level at an i…

Uncommanded Climb illustration 3

What the Climb Means for the Mansfield Case

Whether the helicopter truly climbed on its own has major implications for how the encounter is interpreted.

If the altitude gain occurred substantially as described, the event becomes more than a report of an unidentified light. It would involve an apparent effect on an aircraft, making the case significantly harder to explain through simple misidentification alone.

If, however, the climb resulted from unnoticed control inputs, imperfect recollection, or instrument interpretation during a stressful night encounter, then the most extraordinary element of the story becomes much less certain. The sighting would still be unusual, but it would no longer require an external force acting on the helicopter.

That unresolved question explains why the Mansfield incident continues to attract attention. The reported climb is the case’s strongest piece of evidence and its greatest evidential weakness at the same time. It is dramatic because it suggests something happened to the aircraft itself, yet the proof rests on remembered cockpit readings rather than data that can be independently checked. In the history of Ohio UFO reports, that tension is precisely what keeps the Mansfield helicopter encounter open to competing interpretations.[cufos.org]cufos.orgA Helicopter UFO Encounter Over OhioCenter for UFO StudiesA Helicopter-UFO Encounter over OhioOctober 30, 2023 — by J Zeidman · Cited by 4 — The encounter between a military…Published: October 30, 2023

5:01

UFO Encounter - Mansfield, Ohio 1973 "The Coyne Incident"

Channel: Explorer1x · Views: 23.1K · Uploaded: May 2010 · Length: 5 minutes

Open on YouTube

Amazon book picks

Further Reading

Books and field guides related to What Caused the Mansfield Helicopter's Sudden Climb?. Use these as the next step if you want deeper reading beyond the article.

Browse more on Amazon:UFOs: Generals, Pilots, and Government Officials Go on the RecordThe UFO Experience: A Scientific InquiryThe Report on Unidentified Flying Objects

As an Amazon Associate I earn from qualifying purchases.

eBay marketplace picks

Marketplace Samples

Live-tested eBay searches with available results related to this page.

UsingUSA

Selected fromArmy helicopter patch oneBay.co.uk.

Browse more oneBay.co.uk

Example items shown for inspiration; availability and pricing can change. Branchoria may earn a commission if you purchase through outbound eBay links.

Endnotes

1. Source: uapglobe.com
Title: coyne helicopter 1973
Link:https://uapglobe.com/cases/coyne-helicopter-1973

Source snippet

Radio contact returned only after the object was gone. The magnetic compass never worked...Read more...

2. Source: facebook.com
Link:https://www.facebook.com/viceuk/posts/a-senior-intelligence-officer-described-a-ufo-encounter-with-a-helicopter-that-a/1374724091192336/

Source snippet

Yet we had climbed from 1,700 to 3,500 feet with no power in a couple of seconds with no g-forces...Read more...

3. Source: ashlandsource.com
Title: coyne incident over charles mill lake was most credible ufo sighting of 1973
Link:https://www.ashlandsource.com/2020/10/04/coyne-incident-over-charles-mill-lake-was-most-credible-ufo-sighting-of-1973/

Source snippet

Coyne Incident over Charles Mill Lake was most credible...4 Oct 2020 — The helicopter was cruising at 2,500 feet above sea level at an i...

4. Source: kevinrandle.blogspot.com
Title: it the helicopter was due to the unconscious, instinctive
Link:https://kevinrandle.blogspot.com/2025/04/following-is-long-posting-about-coyne.html

Source snippet

A Different Perspective: The Coyne Helicopter Case24 Apr 2025 — It is a detailed examination of the case that includes the skeptical argu...

5. Source: facebook.com
Link:https://www.facebook.com/ohiomagazine/posts/what-happened-in-the-skies-over-charles-mill-lake-on-oct-18-1973-still-sparks-cu/1392032946260763/

Source snippet

Ohio's best-documented UFO encounter: The Coyne IncidentCoyne increased the airspeed and rate of descent. The last altitude he no...

6. Source: ryan-sprague51.medium.com
Title: The Coyne Helicopter UFO Incident | by Ryan Sprague | Medium
Link:https://ryan-sprague51.medium.com/the-coyne-helicopter-ufo-incident-922d80c6a8b8

Source snippet

Klass, a noted UFO skeptic, proposed that the crew had actually misidentified a meteor, suggesting that the green light was a result...

7. Source: facebook.com
Title: the undiscovered
Link:https://www.facebook.com/photo.php?fbid=122193338840937231&set=a.122105040062937231&type=3

8. Source: facebook.com
Link:https://www.facebook.com/groups/61123668011/posts/10167650401533012/

9. Source: facebook.com
Link:https://www.facebook.com/mrballen/posts/this-photo-was-taken-in-1987-at-the-fleet-air-arm-station-in-yeovilton-england-a/902473878818113/

10. Source: cufos.org
Title: A Helicopter UFO Encounter Over Ohio
Link:https://cufos.org/PDFs/books/A%20Helicopter-UFO%20Encounter%20Over%20Ohio.pdf

Source snippet

Center for UFO StudiesA Helicopter-UFO Encounter over OhioOctober 30, 2023 — by J Zeidman · Cited by 4 — The encounter between a military...

Published: October 30, 2023

Additional References

11. Source: ohiomagazine.com
Link:https://www.ohiomagazine.com/ohio-life/article/the-case-of-ohio-s-best-documented-ufo

Source snippet

was actually rising more than 3,500 feet above the ground.Read more...

12. Source: youtube.com
Link:http://www.youtube.com/watch?v=dllcDPLQfK8

Source snippet

UFO Encounter - Mansfield, Ohio 1973 "The Coyne Incident"...

13. Source: youtube.com
Title: Best UFO Cases: The Coyne Helicopter Incident
Link:http://www.youtube.com/watch?v=NPFLOvnCcqY

Source snippet

The 1973 Mansfield UFO Encounter | The Coyne Incident Recreated...

14. Source: instagram.com
Link:https://www.instagram.com/reel/DaimnmByg5J/

15. Source: instagram.com
Link:https://www.instagram.com/reel/DUKnil_gKZE/

16. Source: reddit.com
Link:https://www.reddit.com/r/aliens/comments/15tv6b3/the_coyne_incident_a_ufo_a_helicopter_and/

17. Source: richlandsource.com
Link:https://www.richlandsource.com/2022/04/29/out-of-this-world-coyne-incident-focused-ufo-attention-on-north-central-ohio-in-1973/

18. Source: youtube.com
Link:http://www.youtube.com/watch?v=RadMLHsfJbQ

Source snippet

Best UFO Cases: The Coyne Helicopter Incident...

19. Source: freepress.org
Title: ohio against universe 50th anniversary ufo wave during halloween 1973
Link:https://freepress.org/article/ohio-against-universe-50th-anniversary-ufo-wave-during-halloween-1973

20. Source: youtube.com
Link:http://www.youtube.com/watch?v=aaj96wWW_qI

Source snippet

You stopped this response...