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Tuesday, February 23, 2010

Following GPS Into Trouble

Ever participated in or heard of a SAR mission necessitated by a driver blindly following a vehicle GPS device (sometimes called "Sat Nav) into trouble? Here in Arizona, the shortest route to a destination certainly isn't always the best route, with drivers occasionally ending up stranded in remote areas on rough, unpaved roads that sometimes all but disappear into the desert. 

After recently reading the story, Couple Following GPS Unit Stranded For Three Days, I decided to see how many related stories I could find. In about thirty-minutes' time, here's what I came up with, including this video:

Or view the video on YouTube.

Related news articles:

11-Year-Old Boy Dies After Mom Says GPS Left Them Stranded in Death Valley
The mom told rescuers in California's San Bernardino County that her son days after she fixed a flat tire and continued into Death Valley, relying on directions from a GPS device in the vehicle.

GPS Unit Leads Truck Driver Into Train Collision
A Florida big rig driver said his GPS instructed him to take a right turn just before the crossing and continue down the unpaved path.

Couple Gets Stranded After Following GPS "Advice"
It was supposed to be a quick trip to see family for Christmas, but a GPS’ offer of a shorter route left one couple and their young daughter stranded in deep snow in the middle of nowhere.

Road To Nowhere: GPS Leading Some Colorado Drivers Astray
Drivers on their way to Crested Butte are led down an old mining road, which hasn't been maintained since the 1800's. It's impassable in the winter and in the summer.

Sat-Nav Driver's 1,600-Mile Error :
A truck driver programmed his destination--the Rock of Gibraltar--as he left Turkey, but because Gibraltar is technically part of the UK, the device routed him to another Gibraltar – a shore town in England.

Sat Nav Driver's Car Hit By Train :
A 20-year-old's GPS led her to a gate she didn't realize was a railroad crossing.

Sat Nav Dunks Dozy Drivers In Deep Water
Since a road was closed, dozens of UK drivers have followed directions from their satellite navigation systems, not realizing that the recommended route goes through a ford.

GPS Routed Bus Under Bridge, Company Says:
A charter bus driver ferrying a high school softball team relied on a GPS system and didn't notice the clearance signs. The 11-foot high bus plowed into a 9-foot high bridge. 23 people were briefly hospitalized and the bus was destroyed.

Sat Navs Damage 2,000 Bridges Per Year
UK's Network Rail claims 2,000 bridges are hit every year by truck drivers who've been directed along inappropriate roads for their size.

Driver Follows GPS Into Sand :
An 80-year-old blindly follows his GPS into a construction site, and his vehicle gets trapped in sand.

Motorists Switch Sat Nav On, Brain Off :
A German man's GPS system said "turn right now," and he obeyed. He collided with a structure, damaging his car and the structure. He was fined.

£96,000 Merc Written Off As Sat Nav Leads Woman Astray
Following the instructions on her navigation system to use a creek ford, the driver failed to notice it was swelled by torrential rain. The car was swept away and she had to be rescued. The car was a total loss.

Tuesday, February 2, 2010

A Follow-Up To Determining Direction Of Sound

My previous blog post, Determining Direction of Sound During a Search received some very interesting comments, including a couple from Del Morris of the Sonoma County Sheriff's Search & Rescue / Helo Unit. Del wrote an article (2003) about the use of sound during searches:


The controlled use of sound during searches for a responsive subject is a stratagem that should be a practice of every SAR Team.

At a "Sound Sweep" exercise, we were debriefing our "victims" and our searchers, graphing/mapping the time and location of each "whistle blast" and the victim's perception of direction from where the sound was coming from. We discovered that the distance of sound travel and perception of sound direction was so variable that it deserved further study.

After some additional field testing and research in acoustics, I offer the following suggestions:

1] Shift to lower frequency whistles 2000-3000 Hz or fog horns (marine supply) Plastic horns(sports events) Compressed air horns (marine supply). The higher frequencies are “absorbed” by humidity and vegetation.
The lower frequencies will more readily bend around vegetation and rocks.

2] “Whistle Blasts” a.k.a. “Whistle Stops” can be done during the normal course of a Team Assignment whenever you are "inline" with a drainage *** Contact SAR Base and request a "WHISTLE STOP". SAR Comm. will then orchestrate a "Whistle Stop" by contacting all Teams, giving all teams time to get "inline" with other drainages, and doing a count down ( 3...2...1) to a great blast" just like during a "sound sweep" ... followed by that all important listening period.

3] Teams that are on ridges will be at a disadvantage. Their whistles will be difficult for the subject to discern direction of the team. The subjects return whistle blows or yells for help will be equally difficult for the team to accurately determine the location of the subject.

4] Teams that are at the bottom (below the subject) of a drainage will a)have the best chance of hearing the subject in the drainage and b) have the most accurate direction of where the subject is. They will hear the subject better than the subject will hear them.

5] Teams that are at the top (above the subject) of a drainage will a)have the best chance of the subject in the drainage hearing them and b) have the second most accurate direction of where the subject is. The subject will hear them better than they will hear the subject.

6] Frequency is more important than additional decibels. 3 -110db whistles does not equal 330db. The combined decibel level is only about 117db. Sound level does not build exponentially. Some frequencies “blown” side by side can actually cancel each other do some degree.

DISTANCE was greatly increased with the lower frequencies of sound (yelling was heard a lot further than a whistle). The lower feqs are not gobbled up as readily by vegetation and the moisture in the air. I reference the use of low freqs in Fog Horns. Our “victims” all heard "yelling" before they heard a discernible "whistle" at a time when the "yelling" teams were further away. Whistles seemed to be blended with the crickets and other background noises.

DIRECTION or the perception of direction was more accurate when teams were "blowing" or yelling while inline with the drainage where the victim was. Blows that were blown by teams that were on the sides of hills or tops of ridges ... the victims found the sound very difficult discerning from "forest" noise and on the whole non-directional.

Sound seems to carry better up hill than down hill, better with the wind than against.

WHISTLE STOP can be used during any "phase" of a search for a responsive subject. Hasty teams running trails, dog teams doing area searches, etc. ... WHISTLE STOP is a more effective use of person power.
A comparison could be made between "closed grid" search lines (Sound Sweep) and "open grid" purposeful wandering (WHISTLE STOP) searching methods.

Del Morris
Sonoma County (CA) SAR Unit