For most operators, the Bosporus is a documentation problem — the SP-1 form is the front door, and the form-level rules are what surface at convoy confirmation. The reality at the Kandilli observation is more physical: the Istanbul Strait Traffic Separation Scheme (TSS) divides the strait into northbound and southbound traffic lanes separated by a separation zone, the Turkish Straits Vessel Traffic Service (TSVTS) administers those lanes through a specific VHF channel set, and the bridge team is required to extend the channel-set listening duty continuously throughout the transit while sending position reports on a 6 nautical mile / 3 nautical mile cadence. The SP-1 documentation and the PEC rules (covered in the prior two Bosporus cluster posts) describe the form-level mechanics of the straits; this third post covers what happens on the bridge — what the TSS lanes actually look like, which VHF channel set TSVTS monitors, how the VTMIS position-reporting cadence connects to the SP-1 ETA window, and where the PEC waiver carves out, and where the TSS regime overrides it.
This is the third leg of the Bosporus chokepoint cluster. The first post — Bosporus SP-1 documentation requirements — covers the 16 supporting-document set behind the form. The second post — Bosporus Pilot Exemption Certificate requirements — covers the LOA / draught / vessel-type thresholds for the PEC regime and the SP-1 Field K/L activation. Together they cover the documentation layer and the authorisations layer; this third post closes the cluster with the operational layer that surfaces on the bridge: the Istanbul Strait TSS geometry, the TSVTS coordination layer, the VTMIS position-reporting cadence, and the SP-1 Field K/L activation that ties the TSS regime into the pre-arrival notification system.
Validate the Bosporus TSS / VTS Workflow Before You Submit
The TSS regime, the TSVTS channel-set listening duty, the VTMIS position-reporting cadence, and the SP-1 Field K/L activation are four separate layers that have to reconcile at convoy confirmation. CanalClear's Bosporus validator runs the full 16-field SP-1 against the on-board documentation set — including the TSS / VTS / VTMIS vessel-side records — and flags any field that would trigger a TSVTS rejection at the Kandilli observation before your agent hits submit.
Validate Bosporus FilingWhat the Istanbul Strait TSS Actually Is and Where It Sits on the Approach
The Istanbul Strait is one of three Turkish Straits that connect the Aegean Sea to the Black Sea via the Sea of Marmara, and the Traffic Separation Scheme that governs it is the operational navigation framework under which every commercial vessel transits the Bosporus. The TSS divides the strait into two one-way traffic lanes — a northbound lane proceeding from the Sea of Marmara / Üsküdar / Kadıköy approach up to the Black Sea exit, and a southbound lane proceeding in the reverse direction — separated by a separation zone that the Kandilli / Yeniköy / Üsküdar bend geometry constrains. The TSS is not a vector drawing on a chart; it is a routing system with specific lane-discipline rules, specific traffic-direction rules, and a specific right-of-way rule that the Montreux Convention 1936 — Article 2 in particular — underwrites as a freedom-of-navigation regime.
Three layers sit on top of the Istanbul Strait TSS, and a working mental model for the cluster rail needs to keep them separate. The first is the TSS lane structure itself — northbound / southbound lanes, separation zone, Kandilli observation line — which is a routing and navigation rule overlay. The second is the Turkish Straits Maritime Traffic Regulations — the substantive maritime regulation that defines the SP-1 pre-arrival notification requirement, the VTS coordination layer, the VTMIS position-reporting cadence, and the operating-window rules for the TSVTS. The third is the SP-1 form layer — the 16-field pre-arrival notification that activates the TSS-aware approach and ties the VTMIS cadence / ETA window / waypoint sequence to the bridge channel-set monitoring duty. A TSS regime operator-mistake at any of these three layers surfaces downstream in the others; the system does not allow a TSS breach to be hidden by a clean SP-1.
The mental model: The TSS is the routing layer. The Turkish Straits Maritime Traffic Regulations are the substantive maritime layer that defines the SP-1, the VTS channel-set, and the VTMIS cadence. The SP-1 is the document layer that activates the TSS-aware approach. All three layers reconcile at convoy confirmation; a TSS breach upstream surfaces as a SP-1 documentation discrepancy downstream.
For the broader sub-straits context (Montreux navigation regime, VTSC coordination, and the wider regulatory stack), the Turkish Straits transit compliance guide is the relevant companion. For the documentation layer specifically — the 16 supporting-document set, the ISSC / BWRB / CSR cross-checks, and the SP-1 Field tier mechanics — the Bosporus SP-1 documentation requirements post is the first leg of this cluster.
The TSVTS VHF Channel Set and the Bridge-Monitor Obligation
The TSVTS coordinates the Istanbul Strait TSS through a specific VHF channel set, and the bridge team is required to maintain a continuous listening watch on the relevant channels throughout the transit. The channel-set is not a single-channel listening duty: the operating mix onboard a transiting vessel includes several channels at once, and missing one of them constitutes a TSS breach that surfaces as a SP-1 documentation discrepancy at TSVTS portal layer.
For 2026 Bosporus transits, the VHF channel set that TSVTS monitors and the bridge team is required to monitor is laid out in the table below. The table is the channel-set reference point that ties to Field K/L of the SP-1 (Field K/L activates the operating-window declaration that the VHF listening-duty has been configured for the TSS approach).
| VHF channel | Role on the Bosporus TSS | Bridge-team obligation |
|---|---|---|
| Channel 11 | Primary TSVTS traffic-coordination channel for the Istanbul Strait sector | Continuous monitoring from the southern Bosporus approach through to the Black Sea exit; mandatory response to sector calls within minutes. |
| Channel 12 | Sector-specific layer at the Kandilli / Yeniköy observation lines | Monitored from the southern approach; sector-call responses within the TSVTS operating window. |
| Channel 13 | Sector-specific handover between Kandilli and the Bosporus exit | Monitored during the Kandilli-to-Black-Sea segment; tied to the Vessel Position Reporting cadence. |
| Channel 14 | Dardanelles / Sea of Marmara sector handover | Monitored in the Sea of Marmara approach; bridges the Bosporus transit to the Dardanelles transit. |
| Channel 16 | International distress, safety, and bridge-to-bridge calling | Continuous monitoring throughout the transit; bridge-to-bridge advisory layer. |
The channel-set row most frequently mis-managed on the Bosporus approach is the configuration at the Kandilli observation line — the operating-window rules require the bridge team to monitor Channel 12 / Channel 13 in parallel with Channel 11, and the typical cause of a SP-1 Field K/L documentation discrepancy is a Channel 12 / Channel 13 listening gap at the Kandilli observation line rather than a Channel 11 miss on the main approach. The whole channel-set listening duty is the bridge-level operational counterpart to the SP-1 Field K/L activation covered in the previous Bosporus cluster posts — the SP-1 declares the operating window, but the channel-set is what the bridge team maintains during the operating window.
Three operational principles govern the channel-set listening duty on the Bosporus approach:
- Channel 11 is mandatory and continuous. VHF Channel 11 is the primary TSVTS traffic-coordination channel. A bridge team that fails to monitor Channel 11 from the southern approach through to the Bosphorus / Black Sea exit triggers a TSS breach at the Kandilli observation regardless of how clean the SP-1 / Field K/L paperwork is. The Channel 11 listening duty is the single non-negotiable layer.
- Sector watches are mandatory at Kandilli. Channels 12 and 13 are sector-specific coordination channels for the Kandilli / Yeniköy observation lines. The bridge team is expected to monitor both during the Kandilli-and-after segment; a pure Channel-11-only post is a TSS investigation trigger even on a vessel with a perfectly valid PEC.
- Channel 16 covers distress and bridge-to-bridge. Channel 16 maintains the international distress, safety, and bridge-to-bridge calling layer throughout the transit. The bridge team cannot surrender Channel 16 monitoring to a secondary set; it has to be on a separate receiver or on a dual-watch head so Channel 11 (mandatory) and Channel 16 (mandatory) are both continuously available.
For the SP-1 / Field K/L activation that ties this channel-set listening duty into the pre-arrival notification regime — the operating-window declaration that the bridge team has configured the channel-set for the Bosporus TSS — the Bosporus SP-1 documentation requirements piece is the relevant companion. The channel-set and the SP-1 Field K/L declaration are two views of the same operating window; a TSS breach at the Kandilli observation surfaces upstream as a SP-1 documentation discrepancy.
VTMIS Position-Reporting Cadence and the TSS Approach Waypoints
The VTMIS position-reporting cadence is the bridge-level operation that ties the SP-1 ETA window to the Istanbul Strait TSS. Every transiting vessel is required to send position reports at three specific thresholds on the Bosporus approach: a 6 nautical mile position report at the southern Bosporus approach on the Sea of Marmara side, a 3 nautical mile position report at the northern Bosporus approach on the Black Sea side, and a final exit position report on leaving the TSS zone. Each position report carries the vessel name, IMO, position, course, speed, navigational status, and the next waypoint, and the position-report sequence must align with the waypoint sequence declared on the SP-1 ETA window.
The position-reporting cadence is the operational counterpart to the SP-1 ETA window declaration: a vessel that declares one waypoint sequence on the SP-1 and reports a different waypoint sequence at the Kandilli observation triggers a SP-1 Field K/L documentation discrepancy and a convoy-slot clock reset. The position reports are not standalone filings; they are the bridge team confirming the SP-1 ETA window is being followed at the operating-window cadence.
| Position report | Threshold / waypoint | TSS regime layer activated |
|---|---|---|
| 1. Southern approach | 6 nm threshold on the Sea of Marmara side of the Bosporus | Triggers the southern-approach waypoint declaration; SP-1 ETA window starts ticking down. |
| 2. Kandilli observation | Kandilli / Yeniköy line — the geometry-constrained apex of the Bosporus approach | Triggers the Kandilli observation sector-call handshake on Channel 12 / Channel 13; the operating window is the densest. |
| 3. Northern approach | 3 nm threshold on the Black Sea side of the Bosporus | Triggers the exit-side waypoint declaration and the final exit position report on leaving the TSS zone. |
The single most common VTMIS position-reporting gap is a vessel that reports the southern-approach waypoint and the Kandilli observation but skips the exit position report on the Black Sea side, on the implicit (and wrong) assumption that the Black Sea exit happens outside the TSS zone. The TSS zone actually extends across the northern exit threshold, and the exit position report is mandatory before the vessel is released from the convoy window.
Practical rule of thumb: The VTMIS position-reporting cadence and the SP-1 ETA window are two views of the same Bosporus transit. The SP-1 declares the waypoint sequence and the ETA window. The VTMIS position reports confirm the bridge team is actually navigating that sequence at the operating-window cadence. A vessel that gets one right and the other wrong triggers a Field K/L documentation discrepancy.
For the broader navigation-rules framework that governs the Istanbul Strait — including the wider Turkish Straits maritime traffic framework and the SP-1 supporting-document set the bridge team has to carry on board — the Bosporus SP-1 documentation requirements post is the relevant companion. The VTMIS position-reporting cadence is the navigational counterpart to the SP-1 supporting-document set; both have to be configured correctly before the Bosporus transit can be reconciled at the Kandilli observation.
TSS Lane Discipline vs. PEC: Where the Carve-Out Stops
The Bosporus Pilot Exemption Certificate (PEC) regime covered in the previous cluster post (see Bosporus PEC requirements) is a narrowly-scoped carve-out from compulsory pilotage only — it does not waive the TSS lane-discipline rules, the TSVTS channel-set listening duty, or the VTMIS position-reporting cadence. A PEC-holding vessel is still required to enter the Istanbul Strait TSS on the assigned side of the separation zone, monitor VHF Channel 11 throughout the transit, send the position reports at the 6 nm / 3 nm / exit thresholds, and respond to TSVTS sector calls on Channels 12 and 13 at the Kandilli observation line.
Three places where the TSS regime overrides the PEC carve-out on the Bosporus approach recur in the operating-window rules:
- Lane discipline is mandatory even with a PEC. The PEC is a waiver from compulsory pilotage, not a waiver from the IMO-adopted TSS routing rules. A PEC-holding vessel on the wrong side of the separation zone commits a TSS breach at the Kandilli observation regardless of how clean the PEC documentation is.
- Channel-set monitoring is mandatory regardless of PEC status. The bridge team's VHF Channel 11 monitoring duty applies to every commercial vessel — PEC-holding, non-PEC-holding, and vessels in compulsory pilotage. A PEC-holding vessel that fails to monitor Channel 11 at the Kandilli / Yeniköy observation line triggers a documentation discrepancy that sits on the SP-1, not on the PEC.
- VTMIS position-reporting cadence applies to every vessel. The 6 nm / 3 nm / exit-threshold position-reporting cadence on the SP-1 ETA window applies regardless of PEC status. A PEC-holding vessel that reports the southern-approach waypoint and the Kandilli observation but skips the exit position report on the Black Sea side commits a Field K/L documentation discrepancy on a SP-1 that is otherwise PEC-clean.
The PEC + TSS mental model: The PEC is a waiver from pilotage only. The TSS lane-discipline, the TSVTS channel-set, and the VTMIS position-reporting cadence are independent regulatory layers that operate above the PEC regime. A vessel can hold a perfectly valid PEC and still trigger a SP-1 Field K/L documentation discrepancy at the Kandilli observation if the TSS regime is mis-managed on the bridge.
For the LOA and draught ceilings that gate the PEC eligibility itself — the dimensional gates the SP-1 has to declare on Field K/L — the Bosporus PEC requirements post is the relevant companion. The dimensional gates and the TSS lane-discipline rules are two views of the Bosporus regulated layer; a vessel that meets one and misses the other triggers a navigation-layer rejection at the Kandilli observation.
Bosporus TSS and the Dardanelles TSS — the Two-TSS System Across the Turkish Straits
The Istanbul Strait TSS is not the only TSS-adopted routing system in the Turkish Straits — the Dardanelles (the strait that connects the Aegean Sea to the Sea of Marmara on the southern approach side) carries its own TSS for the Çanakkale / Gallipoli approach. The two TSS zones — Istanbul Strait on the Black Sea approach and the Dardanelles on the Aegean approach — are separately administered but jointly coordinated through the TSVTS VTMIS backbone and the VHF channel-set that bridges both straits. A vessel that transits the Bosporus and the Dardanelles during the same voyage is therefore navigating two TSS zones coordinated through one VTS / VTMIS backbone.
The two-TSS system across the Turkish Straits is the operational layer that explains why some SP-1 supporting documents and some channel-set configurations cover both straits and some cover only one. Five operational principles apply across the two-TSS system:
- Each TSS is bidirectionally separated. The Istanbul Strait TSS and the Dardanelles TSS each divide the corresponding strait into northbound and southbound traffic lanes. The two TSS zones are not in series — a vessel transiting both during the same voyage passes through one TSS at a time.
- TSVTS coordinates both via the same channel-set. VHF Channel 14 in particular is the Dardanelles / Sea of Marmara sector-handover channel that bridges the Bosporus transit to the Dardanelles transit. The TSVTS VTS / VTMIS backbone coordinates both straits.
- VTMIS position reports are required in both straits. The VTMIS position-reporting cadence applies in both the Istanbul Strait TSS and the Dardanelles TSS; a vessel that transits both straits during the same voyage reports its position at the 6 nm threshold / 3 nm threshold / exit-threshold cadence in each strait independently.
- Montreux applies to both straits. The Montreux Convention 1936 freedom-of-navigation regime applies to the entire Turkish Straits archipelago, not just the Istanbul Strait. The Bosporus / Istanbul Strait TSS and the Dardanelles TSS both ride on the Montreux regime.
- SP-1 captures both straits. The SP-1 pre-arrival notification covers both the Bosporus transit and the Dardanelles transit during the same voyage — a vessel that transits the Sea of Marmara in either direction is operating in both TSS regimes.
Practical rule of thumb: The Istanbul Strait TSS and the Dardanelles TSS are separately administered but jointly coordinated through the TSVTS VTMIS backbone. A vessel that mis-manages the Bosporus / Dardanelles handover at the Sea of Marmara approach (most commonly by failing to monitor Channel 14 on the Dardanelles-hand-off approach) commits a TSS-layer breach that surfaces as a SP-1 Field K/L documentation discrepancy on a transit that is Bosporus-clean.
For the broader sub-straits context — Montreux navigation regime, the wider regulatory stack, and the SP-1 supporting-document set the bridge team has to carry across both TSS zones — the Turkish Straits transit compliance guide is the relevant companion. The two-TSS system is the Turkish Straits' version of the Suez Canal's two-node pattern (covered in the Suez pre-arrival paperwork companion) but on a navigation-rule basis rather than a paperwork basis.
Validate the SP-1 / SP-1 / TSS / VTS Workflow Before Your Agent Hits Submit
The TSS lane-discipline, the TSVTS channel-set listening duty, the VTMIS position-reporting cadence, and the SP-1 Field K/L activation are four independent regulatory layers that have to reconcile at convoy confirmation. CanalClear's Bosporus validator runs the full 16-field form against the on-board documentation set and flagging the TSS / VTS / VTMIS vessel-side records that the bridge team has to coordinate before transit. The validator surfaces field-level mismatches at convoy confirmation before they become Kandilli observation rejections.
Validate Bosporus FilingWhat Happens When the TSS Routing Is Mis-Managed at TSVTS
The TSS-regime rejection surface on the Bosporus approach is concentrated at the Kandilli / Yeniköy observation line, and the documentation discrepancies that surface at that observation line have specific upstream causes. The five scenarios below cover what 2026 Bosporus fleets are reporting most often — at the TSS / VTS / VTMIS / SP-1 layer instead of the documentation / PEC layer.
| Scenario | What went wrong at TSVTS / Kandilli | Downstream effect |
|---|---|---|
| 1. Under-the-line NNW inbound on the wrong side | The vessel enters the Istanbul Strait TSS on the wrong side of the separation zone at the southern approach. The TSS lane-discipline rule is a directional routing constraint, not an encounter-based right-of-way rule, and the Kandilli observation flags it on first approach. | Kandilli observation flags a TSS breach at first sector call; SP-1 documentation discrepancy logged; convoy-slot clock reset. |
| 2. Missing mandatory VTMIS position update | The vessel reports the southern-approach waypoint and the Kandilli observation but skips the exit position report on the Black Sea side. The 3 nm threshold / exit-threshold cadence has to be in the same waypoint sequence as the SP-1 ETA window declaration. | SP-1 Field K/L documentation discrepancy logged; the vessel is held at the next convoy window until the exit position report is reconciled. |
| 3. Wrong VHF channel tuning | The bridge team configures Channel 11 only and does not monitor Channel 12 / Channel 13 at the Kandilli observation line. The TSVTS sector-call layer is a separate regulatory obligation from the primary channel-set and has to be in place throughout the Kandilli approach. | TSS breach logged at the Kandilli observation; SP-1 Field K/L documentation discrepancy; documentation resets if the channel-set is not in place by the next operating window. |
| 4. VHF Channel 16 / Channel 11 dual-watch gap | The bridge team monitors Channel 11 but loses Channel 16 reception because the VHF radio has only one receiver and distress / bridge-to-bridge traffic is offline. The TSS bridge-team obligation covers Channels 11 / 12 / 13 / 14 / 16 simultaneously during the Bosporus approach. | Bridge-to-bridge advisory layer is offline; SP-1 documentation discrepancy at the Kandilli observation; SP-1 Field K/L resets on the next operating window. |
| 5. SP-1 ETA window / waypoint sequence mismatch | The SP-1 declares a waypoint sequence that does not reconcile to the position-report sequence actually sent via VTMIS. The SP-1 ETA window and the VTMIS position-report cadence are two views of the same Bosporus transit; one arrives at the Kandilli observation on a different ETS / ETA than the other. | SP-1 Field K/L discrepancy logged at convoy confirmation; the vessel is held at the next operating window and the SP-1 has to be resequenced before being accepted. |
The five scenarios above are not independent — a vessel that mis-configures the channel-set at the Kandilli observation will typically also mis-time the VTMIS position report, which surfaces as a SP-1 Field K/L discrepancy that resets the convoy-slot clock. The system is layered, and the upstream-layer breach usually surfaces downstream as a documentation-layer discrepancy. The cheapest path through this is a pre-submission validator that runs the full SP-1 + TSS / VTS / VTMIS configuration against the on-board documentation set before the agent hits submit.
Practical Pre-Transit Checklist for TSS-Aware Bosporus Operators
Before every Bosporus filing on a vessel that has to coordinate the TSS regime + TSS channel-set + VTMIS position-report cadence + SP-1 Field K/L activation, the bridge team and the Turkish agent should run through the same checklist. Every item on it is a yes/no — if the answer to any item is "no," the operating-window declaration has to be re-keyed before the SP-1 is submitted.
- VHF channel-set in place and the bridge team has tested it. Channels 11 / 12 / 13 / 14 / 16 all monitored at the southern approach and during the Kandilli observation; the bridge team has run a radio test on Channel 11 in the last 6 hours.
- VTMIS position-report cadence sequenced against the SP-1 ETA window. The 6 nm / 3 nm / exit-threshold waypoint sequence on the SP-1 reconciles to the position-report cadence the bridge team will use at the operating window.
- Kandilli observation line configured for sector-call response. The bridge team is set up to respond to Channel 12 / Channel 13 sector calls within the 60 s TSVTS operating window at the Kandilli observation line.
- PEC declared on Field K/L of the SP-1 (where applicable). If the vessel holds a Bosporus PEC, the certificate number and current validity are correctly entered on Field K/L of the SP-1 and reconcile to the TSVTS issuance register — but PEC status does not waive the TSS lane-discipline rules.
- TSS lane alignment on the southern approach. The vessel is approaching on the assigned side of the separation zone at the Üsküdar / Kadıköy southern approach, transiting in the assigned direction for the assigned TSS lane.
- SCT paperwork and SP-1 record on board at the Kandilli observation. The SP-1 supporting-document set — the SCT paperwork, the SP-1 receipt, the VTMIS position-report log, and the channel-set log — is in the bridge folder and accessible at the Kandilli observation line.
- Dardanelles TSS layer configured (where applicable). For vessels transiting the Bosporus and the Dardanelles during the same voyage, the Channel 14 Dardanelles-hand-off configuration is in place at the Sea of Marmara approach.
For fleet managers running the same vessel across both the Bosporus and the Dardanelles, the practical pre-filing checklist nodes together the Bosporus TSS lane-discipline layer, the TSVTS channel-set, the VTMIS position-report cadence, the SP-1 Field K/L activation, and the Dardanelles hand-off — five layers that surface in different operating-window windows during the same voyage, and that have to reconcile at the Kandilli observation and at the Dardanelles / Çanakkale observation lines individually.
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Download Free Primer →Frequently Asked Questions
What is the Istanbul Strait Traffic Separation Scheme and where does it apply?
The Istanbul Strait Traffic Separation Scheme is the IMO-adopted routing system that divides the Bosporus into northbound and southbound traffic lanes separated by a separation zone, operating under the Montreux Convention 1936. The TSS applies on the approach to and inside the strait from the southern entry at Üsküdar / Kadıköy to the northern Black Sea exit. The TSS is administered in real time by the Turkish Straits Vessel Traffic Service through VHF channels and the VTMIS position-reporting system, and applies to every commercial vessel regardless of PEC status or pilotage waiver. A PEC-holding vessel is still required to follow the TSS lane-discipline rules and the channel-set monitoring duty.
Which VHF channels does TSVTS use for Bosporus monitoring and which must the bridge monitor?
TSVTS operates the Bosporus VTS through VHF Channel 11 as the primary coordination channel, with Channel 12 and Channel 13 used for sector-specific coordination at the Kandilli / Yeniköy observation lines, Channel 14 reserved for the Dardanelles / Sea of Marmara sector handover, and Channel 16 reserved for international distress, safety, and bridge-to-bridge calling. Every transiting vessel is required to monitor Channel 11 continuously throughout the transit and to respond to TSVTS sector calls on Channels 12 / 13 within minutes. A Channel 12 / Channel 13 listening gap at the Kandilli observation is the most common SP-1 Field K/L documentation discrepancy on the TSS approach.
Does the Bosporus TSS apply to PEC-holding vessels or only to non-PEC transit?
The TSS applies to every transiting vessel regardless of PEC status. The PEC is a waiver from compulsory pilotage only — it does not waive the TSS lane-discipline rules, the VTS channel-set monitoring duty, or the VTMIS position-reporting cadence. A PEC-holding vessel is still required to enter the Istanbul Strait TSS on the assigned side of the separation zone, monitor VHF Channel 11 throughout the transit, send the position reports at the 6 nm / 3 nm / exit thresholds, and respond to TSVTS sector calls on Channels 12 / 13. The PEC and the TSS regime are independent regulatory layers.
How is the VTMIS position reporting cadence linked to the SP-1 ETA window?
The VTMIS position-reporting cadence requires every transiting vessel to send a position report at the 6 nm / 3 nm / exit-threshold thresholds on the Bosporus approach, with each report carrying the vessel name, IMO, position, course, speed, navigational status, and next waypoint. The SP-1 pre-arrival declaration declares the waypoint sequence in the same order, and TSVTS reconciles the position-report cadence against the SP-1 ETA window at convoy confirmation. A vessel whose position reports skip a mandatory threshold, or send the reports out of sequence, triggers a SP-1 Field K/L documentation discrepancy and the convoy-slot clock is reset.
What are the Montreux/Bosporus TSS rules on the right of way for vessels in the TSS lane?
Under Article 2 of the Montreux Convention 1936 and the Turkish Straits Maritime Traffic Regulations, vessels in the Istanbul Strait TSS lanes enjoy freedom of navigation in transit through the straits, but the right of way is governed by the TSS lane structure itself: vessels in the assigned northbound lane proceed northbound, vessels in the assigned southbound lane proceed southbound, and overtaking is allowed only on the side of the lane away from the separation zone. A vessel that reads the Montreux freedom-of-navigation rule as a permission to deviate from the assigned lane on weather, traffic, or commercial grounds commits a TSS breach at the Kandilli observation and triggers a SP-1 documentation discrepancy.