Search Pattern

[Fanie]

When an aeroplane does a search for a vessel in distress, how does the search pattern work, or more to the point, what is the time frame per 'block'
during a search ?

[Submarine Tom]

Fanie,

I am more familiar with "on the water" search patterns but they'll give you a place to Google from.

Sector search, Expanding Square, Parallel Track Patterns, Creeping Line,

Trackline Single-Unit Return Pattern, Barrier Search and Shoreline Search.

The "last known position" (LKP) is usually the starting point depending on elapsed time and winds and currents.

The "time frame per block" varies depending on many variables such as: visibility, what you're looking for, number of resources on scene and what they are, level of fatigue (of searchers), sea conditions, etc.,etc.,etc.

I may be able to be more helpful if you tell me why you ask.

Tom

[Fanie]

Hi Tom,

I know how the reach pattern on the water looks like, ie when a boat is doing a search.

I'm referring to earial search specific. My one friend is a pilot and he says the search plane has a search pattern, meaning the way they look down on the water when they try to find a vessel.

Reason for asking, I am making a flasher one can stuff into your life jacket, if worst comes to worst you can activate the flasher and either a boat or an aeroplane can spot the flash especially at night. I have the flasher flashing contiuous for 20 seconds when activated, you can switch the flasher off and on again to retrigger the 20 seconds flashing, simulating a flare. After 20 seconds it flashes three times fast every 5 seconds to preserve battery life. I have tested on the hard, you can see it 3km+ and that's how far the buildings around allow me to view the flasher. It should be visible much further tho.

What I am trying to figger out is what would the optimal flash rate be so that the search plane would have the best chance of seeing the flashes.

[Submarine Tom]

Fanie,

Thanks for clarifying. I realized you wanted to know about airplane search patterns but I don't know what they are. I am only familiar with on the water searches, so that's what I discribed. In Canada (where I am from and the waters I am familiar with) a flasher (or strobe light) is to flash 60 times per minute to indicate distress. You may want to consider carrying on your person a few hand held flares (mini-rockets - red), a smoke cannister (orange), and/or an orange garbage bag you can blow up with air to make yourself more visible. But, first I would check into what is standard practice in the waters you'll be travelling in.

Tom

[hoytedow]

Fanie, why are you having to make the flasher when there several models of clip-on high intensity strobe flashers readily available? Is this a new product you are prototyping?

[Fanie]

Hi Tom,

The problem with flares are keeping them dry. It's ok if you are on deck in dry weather, but when things are less dry and if someone is overboard and you try and locate the MOB it's not always so easy. Flares are not very reliable and has an expiry date as well. The flasher does not expire and you can recharge the batteries, 500 times min. Standby time on the Li batteries is like a year if you don't use them. I ran the proto for two days non stop to see how the batteries will hold up. Hopefully the mob will be rescued before the batteries gord out

The idea also occured that one can shoot the flasher into the air with a parachute, if connected to a coffee grinder reel you can retreive it and use multiple times over as well.

I would dearly like to test the flasher in bad weather, but I was told I cannot it may set off a rescue operation, so how the f is one supposed to test anything around here. I think it's just the local idiots that is scared you are going to make something worth while. It would be interesting to see if the water in the area it flashes in lights up and what the effect in fog and foam would be like.

This is a new prototype I'm making, but firstly for myself and the crew. I may later add a transmitter / receiver that warns the boat when someone is overboard.

Maybe someone knows someone who knows someone that does aerial searches and could comment on this... I tried to find out locally about this but no response.

[hoytedow]

Why not test it in a tube aimed at your assistant during bad weather so the flash is unnoticed by anyone other than the person the tube is aimed at (your assistant)? That way you can test without setting off any false alarms.

[Fanie]

What kind of a tube ?

[masalai]

80mm storm-water pipe - - those plastic ones taking rainwater from your roof? 4 to 8 ft long with the strobe just inside one end and the other pointed toward your friend (like a big "bazooka" - careful someone may think it is a weapon)

[masrapido]

Fanie, search and rescue operations are not standardised. Every country is free to develop, and they do, their own search patterns. SOLAS has some recommendations, but ultimately, the countries do their own thing. Two patterns prevail, generally, circular and paralel blanket searches. Circular is when the search group reaches the last known position and then circle in predetermined radiuses around that spot. The paralel is when a number of aircraft position themselves to a predetermined distance between each other and fly in the same direction for a period of time, covering wide area over and around the last known position of the ship.

Within the two, there are a number of sub-patterns. If it is a visual aid, the pattern should not be your concern. They all work in a similar way.

[Fanie]

80mm storm-water pipe

At close range the flasher is rather blinding I am most interested in seeing how it will look in waves and at some distance away.

Masrapido,

I think the flash rate is important. I think if you are up there and you just look down you may see nothing but a vast water desert. If you narrow the view into smaller blocks and scan them you may be more likely to see an object. The question is, is my 5 seconds fast or slow enough to be detected ? How high doe these planes fly... at 40 000k I doubt the flasher is any good

[hoytedow]

Fanie, like Mas said, any short length of pipe or tube over 2 feet long and opaque. Keep it light weight since it is just a to obstruct light rays from going where you don't want them to go, like the navy signal lamps of the war.

[hoytedow]

You want it to flash at least 3 times per wave cycle, so that it will be seen at least once per wave, even if 2 flashes out of 3 are in the trough. I don't know how frequent that is, but you can determine from your experience.

[masalai]

Fanie I have seen some "exercises" offshore when I was living on the Sunshine Coast (Buderim), and they seemed to be 500 to 5000 feet, depending on the aircraft, as many regular planes have some difficulty looking down, unless specifically set up for S & R with lower windows near the feet/knees... or can maintain flight upside down... Those old "Viery" (spel?) pistols were a good option as the phosphorous was inside a "shotgun cartridge" and fired from this - - 2 incl barrel bright yellow plastic pistol, - - straight up and would have been an excellent device but this crap fear of "terrorists" using them to hijack planes has stuffed that idea (they are still carried on planes as flares are too dangerous) and the 9/11 effort used cardboard cutting knives locally known here as "Stanley knives", so who is a f&%*ing idiot???

Fanie,
try to get a IAMSAR MANUAL, Volume III : MOBILE FACILITIES. It is mandatory on every merchant vessel and shows you the regulations and procedures of search patterns either by aircraft and ships. The pattern 4 is common standard, thats a parallel web with a horizontal and a vertical track, named "Parallel Sweep Search" another is the "Expanding Square Search"

Visibility is a big point in SAR actions. As a example in clear nights one can see a cigarette glowing over more than one nautical mile! Unfortunately when sh!t happens the weather is not the nicest. If I had to choose a flash interval I would choose 3 flashes every 5 seconds (no long cont. flash), apart from regulations. That is a interval every searching airplanes would notice. They do´nt fly very low at night, so they are not too fast to be out of sight within 5 seconds, less than 3 flashes is not to recommend.
Make a test on a rainy night in the bush, or send the item to Mas, he can do it in OZ (then he has to pay the cost for a false alarm).

Regards
Richard