Overview

Rescue Response Time is a live AIS situational display built for rescue coordination. It shows offshore installations, vessels, charted obstacles, and your active rescue units on a single map, and calculates how many people can be picked up at a given destination within 120 minutes.

1. Set the destination

The destination is the point you want to evaluate for rescue capability. You can set it in two ways:

• Destination lookup — type a vessel, platform, or installation name. Matching fixed installations and known helideck vessels are listed with their position source. For vessels, the live AIS position is used. You can also type GPS coordinates directly: degrees and decimal minutes (ddmm.xx dddmm.xx) or degrees, minutes and seconds (ddmmss.xx dddmmss.xx). Optional decimals and hemisphere letters (N/S/E/W) or a leading minus sign are accepted. Examples: 6123.45 00234.67, 612345.67 0023434.67, N6123.45 E00234.67, or 6123.45N 00234.67E.
• Click on the map — tap any installation, vessel, obstacle, or an empty spot on the map to use that coordinate as the destination. The destination is shown in the top bar, and the map zooms to keep at least 75 nm visible around it.

Once a destination is set, the top bar shows a rescue capability summary for that point.

2. Rescue units

Open the Rescue Units page to see every available unit. A unit must be Active to be included in coverage calculations and in the destination capability summary.

• Aircraft — can be tied to a fixed base position or use the unit's live AIS position. Toggle Use AIS to follow the live position. Each aircraft has a default speed and a rescue capacity (persons). Default cruise speeds: S92 145 kt, A189 145 kt, A139 140 kt. Aircraft range is wind-adjusted per bearing (see Weather below).
• Ships — use the live AIS position. Each ship has a default speed (20 kt default) and a rescue capacity. Ships also have a max significant wave height (default 4.5 m); above this the ship is excluded from the destination total (see Weather below).

3. Multi-aircraft on-scene efficiency

When several aircraft can reach the same point, only one can hoist at a time. The first aircraft to arrive (shortest response + travel time) is credited at 100 % pickup efficiency. Every additional aircraft is credited at 50 % efficiency, i.e. its pickup time per person is multiplied by 1.5. A helicopter with a 3 min per-person pickup is therefore counted as 4.5 min per person when it is not the first on scene.

The rule applies to both the combined rescue coverage polygon on the map and the per-unit destination capability shown in the top bar. Ships are not affected by this rule.

4. Rescue coverage

The Rescue coverage panel on the map shows the area each active unit can reach within a 120 minute budget, including response time, travel time, and pickup time.

• Show coverage on map — turn the overlay on or off.
• Persons — slider from 1 to 21. The coverage radius shrinks as the number of persons grows, because more people take longer to pick up. The base requirement is: response + (persons × pickup per person) + travel ≤ 120 min. For multiple aircraft the on-scene efficiency rule above applies.
• Day / Night — switches the response time and ship response time profiles used in the calculation. Response times are configured in Settings.

Per-unit rings are drawn for each active unit. Aircraft rings are wind-adjusted per bearing (headwind shortens reach downwind of the base, tailwind extends it). Ships that exceed their max wave height at the destination are excluded from the total.

5. Rescue capability at destination

When a destination is set, the rescue capability box lists every active rescue unit that can pick up more than one person at that location within 120 minutes. Each unit shows the number of persons it can rescue, the distance to the destination in nautical miles, and the unit's current location (nearest fixed base or AIS position). The total rescue capacity is shown on the far right.

A unit shown with a red number means the forecast wave height at the destination exceeds that ship's max Hs — it is listed for reference but not included in the total. An orange background on wave samples along the way is a visual clue that Hs is above one or more ships' limit somewhere in the area.

6. Dragging a rescue unit

Active rescue units can be repositioned directly on the map. Click and hold the left mouse button on a rescue unit marker, then drag it to a new location. A straight vector is drawn from the original position to the new position, and an information box shows:

• New GPS coordinates of the dragged unit.
• Bearing and distance from the original position to the new position.
• Estimated time en route — for aircraft this is calculated using the wind along the path; for ships it uses the unit's configured speed.

Releasing the mouse button leaves the unit at the new position. The vector and information box remain visible. Click the Reset button in the information box to return the unit to its original position and remove the vector and box. While a unit is in a dragged position its text in the rescue capability box is shown in orange as a reminder that it has been moved from its original location.

Position and coverage calculations are updated with a short delay while dragging so the map stays smooth. The final values are calculated once the drag stops or the mouse is released.

7. Weather (wind and waves)

Wind and wave data are fetched from MET Norway:

• Wind — locationforecast 2.0 (10 m wind speed and direction).
• Waves — oceanforecast 2.0 (significant wave height, Hs).

Both feeds are hourly forecasts. The timeline slider at the bottom of the map picks the valid time; wind and wave samples, aircraft coverage and ship exclusion all follow that time.

Layers panel toggles the visual samples:

• Wind barbs — standard meteorological barbs pointing into the wind. Half feather = 5 kt, full feather = 10 kt, pennant = 50 kt.
• Significant wave height — numeric Hs in metres at each sample point. The sample tile is shown with an orange background if Hs exceeds any active ship's max Hs, as a heads-up that ship pickup may not be possible in that area.

Aircraft coverage is wind-adjusted per bearing. The system builds a wind sample grid around each aircraft with up to roughly 50 nautical miles between points, and uses bilinear interpolation to estimate the wind at any point inside the coverage area. For each bearing the wind is sampled along the path from the aircraft to the edge of the disc and averaged, giving a mean headwind or tailwind component. The aircraft's true airspeed is then converted to ground speed (TAS plus or minus the wind component along that bearing), so the reachable distance within the 120 minute budget is longer with a tailwind and shorter into a headwind. The same wind path average is used when an aircraft is dragged to a new position, so the displayed distance, bearing, and estimated time en route reflect the forecast wind along the proposed route.

Ship exclusion compares the forecast Hs at the destination to the ship's max Hs; if exceeded, the ship is dropped from the total (red number in the rescue capability box).

8. Settings — defaults

The Settings page holds every parameter the coverage engine uses. Built-in defaults:

• Cruise speed — S92 145 kt, A189 145 kt, A139 140 kt, ship 20 kt.
• Pickup time per person — 3 min (helicopter), 3 min (ship). Multiplied by the number of persons on the coverage slider; late-arriving aircraft use ×1.5.
• Ship response time — 15 min day, 20 min night.
• Response time per base — minutes from alert to takeoff, per base, day and night; edit in Settings.
• Ship max Hs — 4.5 m default per ship; editable per unit on the Rescue Units page.
• Time budget — 120 min, fixed.
• AIS — BarentsWatch API key and radius.

9. Map symbols and colour coding

Each target type on the map has a distinct colour so you can tell at a glance what you are looking at and how trustworthy the position is.

• Blue — Fixed installation. Platform or rig with a fixed, surveyed position.
• Pink — Helideck vessel (known). Known helideck vessel with a live AIS position. Pink regardless of fix age so the helideck fleet is always recognisable.
• Green / Orange — Other AIS vessel. Any AIS target that is not a known helideck vessel. Green when the last AIS fix is within the past 5 minutes, orange when older than 5 minutes. The last fix time is shown in the info box when the target is selected.
• Yellow — Fixed obstacle. Charted offshore obstacle. Always yellow — position is fixed and does not rely on AIS.
• Green shaded area — Rescue coverage. The combined area reachable by all active rescue units within the 120 minute budget for the selected number of persons.
• Orange wave sample. Significant wave height at that sample exceeds at least one active ship's max Hs — a visual heads-up, not a hard exclusion by itself.

10. Working with traffic

All AIS targets on the map are clickable. Selecting a target shows its details and lets you use it as the rescue destination — useful when you need to evaluate a nearby vessel or installation.

AIS data

AIS (Automatic Identification System) is a maritime tracking system where vessels broadcast identity, position, course and speed over VHF. Coastal receivers aggregate these messages, and this app displays the resulting live picture of traffic around your destination.

SAR aircraft (MMSI starting with 1) are filtered out of the display.

The vector line extending from each AIS target shows the expected position one hour ahead, based on its current course and speed.

AIS data and API are provided by BarentsWatch. Credit and thanks to BarentsWatch for making the feed available.

Contact

Found a problem, experienced an error, want to add a unit, or need to report a missing fixed obstacle? Send an email to mikael.botnen@swedishairservice.se.