SEAL William "Blake" Marston

[Blizzard]

Godspeed.

 

[SkrewzLoose]

Fair winds and following seas, Warrior.

 

[AWP]

The Navy's report is out and summarized in the article below.

Virginia Beach-based SEAL who died in accident was unconscious, never opened parachute

Why Petty Officer 1st Class William Blake Marston blacked out remains a mystery that Navy investigators said they couldn’t solve. Marston’s parachute and equipment were in good working condition.

The earlier bit about something coming off of his parachute, was probably his reserve freebag.

Marston wore an automatically activated reserve parachute that opened at 750 feet. But investigators believe that chute’s canopy was fully open for only one to two seconds before impact.

BSBD.

 

[DA SWO]

The Navy's report is out and summarized in the article below.

Virginia Beach-based SEAL who died in accident was unconscious, never opened parachute



The earlier bit about something coming off of his parachute, was probably his reserve freebag.



BSBD.

Is 750 feet too low for the reserve?

 

[AWP]

Is 750 feet too low for the reserve?

Yes and no. An AAD (I'd guess he wore a CYPRES but I don't know) fires when it senses certain parameters, rate of descent and altitude. Newer AAD's allow you to adjust the opening altitude/ firing of the AAD with the base as 750' (to my knowledge 750's been the standard for about ever) because some reserves haven't opened in time.

AAD Activation Altitude | Parachutist Online

Concerning the rate of descent, a jumper falling stable, belly-to-earth is around 110-120 mph. A freeflyer (basically anyone not belly-to-earth) is clocking in around 150-160 mph. Someone unconscious can/ usually falls erratically and with a higher rate of descent than a controlled freefall.

Not knowing the precise details of PO1 Marston's jump, if he were totally unconscious or unstable his rate-of-descent would be in excess 120 mph which will decrease his reserve's "working time." 750' is usually enough but we've seen that isn't always the case. The article states his canopy was fully inflated, but that doesn't translate into a slow vertical rate of descent. Square canopies have to transition from a vertical opening to "flight" when they move more horizontally. A fully inflated canopy will "shake itself out" in 20-50 feet. Even at full flight a downwind landing can be rough, but I don't know his landing attitude, direction, wind speed, etc. The point there is an open canopy can still injure you depending on the circumstances and variables.

120 mph is 1.467 mph or 176 feet per second. Activating at 120mph @ 750' gives one 4.261 seconds at terminal; of course you start decelerating once the reserve fires. 150 mph is 220 fps or 3.41 seconds at terminal. If you look up "AAD fire" or something similar on Youtube, you'll see all sorts of videos with anything from 4-5 seconds of canopy time to 2-3 seconds. Canopy activations aren't the same from rig to rig, terminal velocity plays a role as well, but that higher velocity also translates into less time for the opening to work. There are a bunch of variables that go into how fast a canopy will open.

 

[Ocourse]

Very sorry to hear.