Posted on 01/03/2011 7:02:37 AM PST by Tina Grazier
At 12:47 p.m. on December 9, 1999, the CH-46 Sea Knight lifted off from the Bonhomme Richard as the lead of five helicopters on an exercise to train Marines how to "take down" a hostile ship at sea. While SEALs boarded the ship from rubber boats, the Marines would lower themselves hand over hand from a rope dangling from the hovering helicopter. As part of the exercise, the Marines lugged assorted weapons and breaching tools, including 16-pound hammers and 30-pound cutting torches.
The Sea Knight proceeded uneventfully to a designated holding pattern 10 to 12 miles behind the rear of the target ship, the oiler Pecos, manned mostly by civilians. At 1:06 p.m., with 10 miles' visibility, a 3-knot breeze and an air temperature of 60 degrees, the helicopter was given approval by the Pecos to begin an approach. At an initial speed of slightly more than 100 mph and an altitude of 100 feet, the helicopter headed toward the ship.
When the helicopter was about a quarter-mile behind the Pecos, Cpl. Adam Johns, a member of the flight crew, told one of the pilots, Capt. James Lukehart Jr., that the helicopter was "coming in fast."
"Yep, I'm going in fast," Lukehart replied as he slowed things down.
Lukehart and the other pilot, Capt. Andrew Smith, cut speed to about 60mph and kept the aircraft at an altitude between 65 and 100 feet.
Smith gave a one-minute warning so the Marines could unbuckle and prepare to stand and lower themselves through the hell hole. Smith then gave a 30-second warning, by which time all the Marines were standing.
SEALs in boats behind the Pecos thought the helicopter was flying low; perhaps the Marines planned to land rather than hover. Marines aboard the CH-46 observed an inordinate amount of propeller wash in the water.
The chief mate aboard the Pecos, assigned as a landing safety officer, saw the helicopter at 100 yards out and began to provide arm and hand signals for the pilots to increase power and altitude. But he was dressed in white, not the traditional yellow for......
(Excerpt) Read more at ChicoER Gate
Huh?
oops, I meant 10 years.
Now I know why OneVike didn’t post his article here.
Oh Well.
Very sad. Shocking video to see.
The standard practice of “fast roping” does not involve lowering oneself “hand over hand”. It’s more like a fireman’s pole.
It was apparent from the video that the fast approaching aircraft sink-rate was too fast for the pilot to arrest the descent without either hitting the water or the deck of the ship.
Sad.
However, he was pilot in command of the aircraft and the excuse that he should be relying on someone on deck to give him directions seems rather poor.
This reminds us that even in peace time our armed forces face many dangers.
Semper Fi!
bump
I can’t remember what the name of the effect is exactly but “dynamic rollover” doesn’t sound quite right and when I looked it up, dynamic roll over requires one landing gear to be on a hard surface and for the CG to be tilted way off the center of lift.
What happened in this case was that the deck side of the rotors get more lift due to the increased ground effect (deck effect?) lift whereas the sea side of the rotors see less ground effect as they are higher off the ground (sea). Note that when the copter is coming in, the rear (sea) side dips.
I did more poking around to find the exact phrase but this was the best I could do, http://www.helicoptercrashes.com/helicopter-operational-terms . Note the height of “In ground effect” vs. “Out of ground effect”. Sorry but I never did find the exact phrase.
Click on pic for past Navair pings.
Post or FReepmail me if you wish to be enlisted in or discharged from the Navair Pinglist.
The only requirement for inclusion in the Navair Pinglist is an interest in Naval Aviation.
This is a medium to low volume pinglist.
The helo crashed as a result of dynamic rollover. If you look closely, the port main landing gear is hooked on the safety net. Ground effect does not really cause power requirement differentials between the two rotor systems in the H-46 to significantly affect the attitude of the aircraft except in the ground cushion area of about 2 -3 feet.
For ground effect to cause problems, the aircraft would need to have the whole front rotor system over the ground, the whole aft rotor system not over the ground (never happens because of the design of both the airframe and the flight control system) and the aircraft would need to be overloaded.
Thanks. I missed the landing gear being caught in the net.
Remarkable video. Reading the text on the webpage, it references a “heicopter flotation device” that failed to deploy. I wasn’t aware such a thing existed. Couldn’t find any info..nor any reasons as to why it didn’t work. Can you provide any more data? Thanks
The system is the Helicopter Emergency Flotation System (HEFS). It consisted of two inflatable balloons located just forward of each stubwing. It was an afterthought add on in the 90’s that was supposed to deploy automatically, but had problems where water vapor would cause the blivets to deploy. Looked pretty funny.
Many thanks....have there been any successful emergency deployments of HEFS? Thanks
Not sure. I believe the procedure was to manually deploy the bags prior to hitting the water if practical, but that would assume the crew had enough control of the aircraft. In dire straits, blowing the bags is probably the last thing on the crews’ minds. I do know of one landing with the HEFS deployed where the bags separated from the aircraft once it hit the water. I guess the super glue they used to attach the balloons to the fuselage wasn’t quite up to Navy snuff.
Through the years, many successful emergency water landings, followed by takeoffs were recorded, sans water-wings. The HEFS was designed to keep the fuselage afloat, but it acts as a huge anchor once the aircraft is in the water.
In my opinion, the HEFS was a feel good band-aid to make the passengers and crew on board think they were safer.
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.
