AIS navigational status
AIS navigational status 0: Under way using engine
Moving under power — and the status nobody remembers to change. What status 0 means, what speed and track should go with it, and how often it is simply wrong.
What status 0 means
The vessel is under way and propelled by its engines. "Under way" in the collision regulations means not at anchor, not made fast to the shore and not aground — so a ship drifting with its engines stopped is still under way.
What should go with it
Anything from drifting to full speed. A reading near zero for hours is the classic sign of a status nobody updated.
Navigational status is entered by hand on the bridge; speed, course and position come from a satellite receiver. Read the status as testimony and the rest as measurement. Where they agree you have learned something. Where they disagree, the measurement is usually right.
How it goes wrong
Ships spend most of their time under way, so 0 is the status most often left set — which makes it the most common value and the least informative. Ships at anchor, alongside and even laid up report 0 because nobody changed the menu on arrival. Believe the speed over ground before this field.
The matching lights and shapes
The AIS status mirrors a state defined in the International Regulations for Preventing Collisions at Sea (COLREGs), which also say what the vessel should display:
Rule 23 — masthead light(s), sidelights and sternlight at night. No day shape.
Summary for orientation only. The COLREGs text is the authority; this site is not a navigation reference.
All sixteen codes
| Code | Meaning |
|---|---|
| 0 | Under way using engine |
| 1 | At anchor |
| 2 | Not under command |
| 3 | Restricted manoeuvrability |
| 4 | Constrained by her draught |
| 5 | Moored |
| 6 | Aground |
| 7 | Engaged in fishing |
| 8 | Under way sailing |
| 9 | Reserved for future amendment (HSC) |
| 10 | Reserved for future amendment (WIG) |
| 11 | Power-driven vessel towing astern |
| 12 | Power-driven vessel pushing ahead or towing alongside |
| 13 | Reserved for future use |
| 14 | AIS-SART, MOB-AIS or EPIRB-AIS active |
| 15 | Undefined (default) |
For the field as a whole — and how this site handles it — read AIS navigational status codes, all sixteen.