ASN Wikibase Occurrence # 54862
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| Date: | Sunday 4 August 1991 |
| Time: | |
| Type: |  Sikorsky CH-124A Sea King (S-61B) |
| Owner/operator: | Canadian Armed Forces (CAF) |
| Registration: | 12439 |
| MSN: | 61382 |
| Fatalities: | Fatalities: 0 / Occupants: 5 |
| Aircraft damage: | Destroyed |
| Location: | Schenectady, NY -
 United States of America
|
| Phase: | Manoeuvring (airshow, firefighting, ag.ops.) |
| Nature: | Military |
| Departure airport: | KSCH |
| KSCH | |
| Confidence Rating: |  Information is only available from news, social media or unofficial sources |
The aircraft had flown to Schenectady N.Y., on a tasked mission: to be part of the static display at the local air show. The accident occurred prior to the start of the air show during pre-show activities. The stated intent was to air move the Sea King to avoid the jetwash of a C-5 Galaxy that was due to taxi.
The aircraft took off at approximately 1040 local, climbed vertically out of ground effect and proceeded on a brief local area familiarization flight. The post takeof check was not done. Crew members were seated at the cargo door at take off and throughout the flight . After a brief flight, the helicopter returned to the airport and entered a high hover in front of the show line, executed a series of pedal turns and climbed vertically to approximately 350 feet AGL. Shortly thereafter the aircraft inadvertently entered a rapid vertical descent (2000 fpm). The aircraft captain was unable to stop the descent prior to impact.
The aircraft hit the ground vertically with the undercarriage retracted and rotated around the left sponson while the main rotor struck the ground repeatedly. The helicopter came to rest on its left side with the left sponson, tail cone and pylon near the aircraft. Four of the main rotor blades departed the aircraft. The crew escaped from the aircraft with assistance from rescue personnel. Three of the crew suffered major injuries and two received minor injuries.
The aircraft was serviceable prior to impact. It was apparent from video evidence, wreckage analysis, and crew testimonies that the aircraft was developing full power from both engines during the descent and impact.
Evidence indicates that the normal pre-flight requirements had been performed in a cursory manner. The crew had only vaguely aware of the captain's intentions. Pre-flight and in-flight calculations to ascertain power requirements and reserve were not done. Post-crash investigation revealed that the aircraft had little power in reserve for out of ground effect hovering.
Conditions at the time ot the accident were ideal for development of a condition known as Vortex Ring State (VRS), where the helicopter is engulfed in its own recirculating down-wash and rapidly looses altitude. In fully developed VRS, application of power merely worsens the condition. Rates of descent can reach 3000 fpm. Recovery involves entering autorotation, lowering the nose to gain airspeed, or combining both manoeuvres. Altitude loss during recovery can exceed a thousand feet therefore successful recovery at low altitude is extremely unlikely. Conditions which will increase the likelihood of encountering VRS are:
a. High power applied to the rotor;
b. high gross weight;
c. light or no wind (low airspeed) ;
d. high density altitude ; and
e. a steep approach (30 degrees or more).
All these factors were present in this case. Video analysis of rates of descent and the pilot's testimony indicate that the aircraft was in VRS when it crashed.
Sources:
http://web.archive.org/web/20071031101840/http://www.ody.ca/%7Ebwalker/CAF_Sea_King_detailed_list.htm
Flight Comment 3/92
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 27-Dec-2009 00:13 | TB | Updated [Cn, Operator, Other fatalities, Source] |
| 28-Dec-2009 12:09 | TB | Updated [Aircraft type, Source] |
| 25-Aug-2011 07:08 | Uli Elch | Updated [Operator, Source] |
| 20-Jan-2012 12:47 | Nepa | Updated [Operator, Source] |
| 21-Dec-2012 11:42 | TB | Updated [Operator, Total fatalities, Other fatalities, Location, Country, Phase, Nature, Source, Narrative] |
| 29-Dec-2021 08:55 | Youz | Updated [Total occupants, Phase, Departure airport, Destination airport, Source, Narrative] |
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