Why does a ship disappear from radar?
Seeing a ship disappear from radar while tracking it can feel confusing or even worrying. One moment, the vessel is clearly visible on the map. Then suddenly, it seems to vanish.
In most cases, there is a perfectly normal explanation. Let’s break it down simply and easily.
How Does MarineRadar Tracking Work?
The MarineRadar app and website rely heavily on the Automatic Identification System (AIS). Before exploring why a ship disappear from radar, knowing about AIS helps to understand how ship tracking actually works.
AIS is a tracking system where ships broadcast information such as their current location, speed, direction, vessel name, and type. This data is transmitted via radio signals and satellites and then displayed on marineRadar platforms.
However, AIS is not a constant, uninterrupted signal everywhere in the world. Because of this, ships may disappear temporarily, even though nothing unusual has happened.
Most Common Reasons Why a Ship Disappear from Radar
1. The Vessel Entered a Coverage Gap
One of the most common reasons a ship disappear from radar is simple geography.
AIS coverage is strongest near coastlines where land-based receivers exist. However, in deep oceans, coverage depends mainly on satellites. These satellites pass over specific areas at intervals rather than continuously.
As a result:
- Ships may temporarily vanish in open waters
- Tracking resumes when satellite coverage returns
This is entirely normal and happens every day.
2. AIS Transmission Was Switched Off
In some situations, vessels intentionally turn off their AIS system. Although this may seem alarming, it is frequently allowed and legal.
Common reasons include:
- Security concerns in piracy-prone regions
- Military or government operations
- Privacy during sensitive voyages
When AIS is turned off, marine radar systems simply stop receiving signals. Therefore, the ship disappears from radar until transmission resumes.
3. Poor Weather Interference
Weather plays a larger role than many are aware of. Heavy rain, storms, or atmospheric interference can weaken AIS signals.
During rough conditions:
- Signals may fail to transmit properly
- Satellite reception may be interrupted.
- Updates can be delayed or missed.
As a result, the vessel may temporarily disappear from the radar map.
4. Slow or Anchored Vessels Update Less Often
AIS updates are not sent at the same frequency for every ship. When a vessel slows down or anchors, it sends fewer updates.
- Movement appears frozen
- The ship may seem missing.
- Data refresh happens less frequently.
However, the ship is still there; it just isn’t transmitting as often.
5. Technical or Equipment Issues Onboard
Sometimes, the issue is as simple as onboard maintenance or technical problems.
Examples include:
- Power interruptions
- AIS antenna issues
- Temporary system resets
Once the equipment is restored, tracking usually returns automatically.
What Does the App Show When a Ship Disappears from Radar?
If a ship disappears from radar, apps don’t leave users confused. Instead, they usually display helpful indicators such as
- Last known position
- “Last seen” timestamp
- Estimated movement path
Should You Be Worried If a Ship Disappear from Radar?
In most cases, there’s no reason to worry. A ship that disappeared from radar does not usually mean danger, loss, or an emergency.
However, you may want to pay closer attention if:
- The ship disappears near a busy port
- No updates occur for many days.
- The vessel was previously moving normally.
Even then, the cause is often technical rather than serious.
Conclusion
When a ship disappear from radar, most of the time, it’s due to signal coverage gaps, AIS settings, weather conditions, or normal vessel behavior.
Marine radar systems are powerful tools, but they still rely on the signals. Once you understand how those signals work, ship tracking becomes far less confusing and much more reliable.
Download Marine Radar: Vessel Tracker from the Google Play Store or App Store today and experience real-time ship tracking.
