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Separation, Routes and Deviations

Without radar, separation is not observed: it is calculated and protected.

Read before applying any number

No minimum on this page stands on its own. Each one depends on a declared and confirmed capability, on the type of route and on the means of communication. Applying a smaller value without the condition being met is reducing separation without grounds.

Decision table

Ask in order and stop at the first row whose condition is met. When more than one row applies, the largest minimum prevails.

Condition Minimum Source
Both RVSM, between FL 290 and FL 410, at different levels 1,000 ft 1 2
Either non-RVSM, or RVSM suspended due to severe turbulence 2,000 ft 3 4
Both RNP 10, parallel or non-intersecting routes 50 NM lateral 5
Either without RNP 10 certification 100 NM lateral 6
Same route and level, Mach number technique, preceding aircraft at equal or higher Mach 10 minutes 7 8
Same route and level, Mach number technique, preceding aircraft faster 9 to 5 minutes, see table 7
Same route and level, Mach number technique, following aircraft faster 10 minutes + compensation 9
Same route and direction, RNAV distance with readings from a common point 80 NM 10 8
Same route and level, without Mach number technique 15 minutes 11
Crossing routes, same level 15 minutes at the intersection 12
Opposite routes, without lateral separation Vertical from 10 minutes before to 10 minutes after the estimated passing 13
Climbing or descending through the level of another aircraft, same route 15 minutes 14

The 10-minute minimum replaces the 15 minutes when navigation aids allow positions and speeds to be determined continuously11 12 14.

Vertical separation

Band Minimum
Below FL 290 1,000 ft
Between FL 290 and FL 410, inclusive 2,000 ft, or 1,000 ft where RVSM applies
Above FL 410 2,000 ft

All of the FIR's airspace between FL 290 and FL 410 is RVSM2, so 1,000 ft is the rule in the cruise band, provided both aircraft are RVSM approved.

Crossing levels. An aircraft may be cleared to a level previously occupied once the other aircraft has reported vacating it, except in severe turbulence, cruise climb, or a performance difference that could reduce the minimum15.

Lateral separation

The published minimum for the EUR/SAM corridor is 50 NM between RNAV aircraft certified RNP 105, and 100 NM for those not certified6. That is the value to use.

For crossing routes, the lateral separation point follows the navigation specification: RNAV 10 (RNP 10) 50 NM, RNP 4 23 NM, RNP 2 15 NM16.

Reduced minima require PBCS

ICA 100-37 provides for 23 NM conditioned on RCP 240, RSP 180 and an ADS-C event contract17. Until the AIP publishes these minima for the corridor, apply 50 NM.

On receiving information of a navigation failure or degradation, apply another type or minimum of separation; minima based on RNAV distance no longer apply18.

Mach number technique

Jet aircraft on the same route maintain specified Mach numbers to ensure longitudinal spacing19. It requires that they have reported the same common point and follow the same route or continuously diverging routes20.

Preceding aircraft faster

Mach difference Minimum separation
0 or 0.01 10 minutes
0.02 9 minutes
0.03 8 minutes
0.04 7 minutes
0.05 6 minutes
0.06 or more 5 minutes

Example

Preceding aircraft at Mach 0.83, following at Mach 0.78. A difference of 0.05 in favour of the preceding aircraft: the minimum drops from 10 to 6 minutes21.

Following aircraft faster

The spacing at the entry point must be increased: add 1 minute for every 0.01 of Mach difference, within 600 NM between the entry and exit points9.

ATS route Points Distance Multiplier
UZ51 DAKAP and MOVGA 517 NM 1x
UN741 JOBER and NANIK 493 NM 1x
UN866 MAGNO and DEKON 475 NM 1x
UN873 VUNOK and TASIL 449 NM 1x
UN857 UTRAM and ERETU 431 NM 1x
UL206 BUGAT and KODOS 340 NM 1x

Example

On UZ51 via DAKAP, preceding aircraft at Mach 0.82 and following at Mach 0.84. A difference of 0.02, multiplier 1x: add 2 minutes to the 10. 12 minutes are required at the entry point22.

Consulting the pilot about a speed adjustment is permitted, but should not be routine23.

Loss of capability

Lost Effect Action
RVSM approval Vertical returns to 2,000 ft Reassign levels before the minimum is infringed3
Navigation accuracy Lateral and RNAV distance minima no longer apply Apply another type or minimum18
ADS-C No automatic position Require reports and re-establish minima24
Assigned Mach number The technique no longer supports the reduced minimum Return to 10 or 15 minutes

Emergency separation. If, during an emergency, horizontal separation cannot be ensured, half the vertical minimum may exceptionally be used: 500 ft where 1,000 ft applies, and 1,000 ft where 2,000 ft applies25. Flight crews must be informed that it is being applied and of its value, and must receive essential traffic information26.

Conflicts near the FIR boundary

  1. Calculate separation at the transfer point, not where the aircraft is now.
  2. Coordinate before acting27.
  3. Resolve it on your side: adjust level, Mach or time before the handoff.
  4. If the adjacent unit is offline, resolve it entirely within your own jurisdiction.

SLOP

Strategic lateral offset is in effect in the Atlântico FIR and is standard pilot practice28:

  • offset to the right only, in three positions: centerline, 1 NM or 2 NM;
  • never beyond 2 NM, never to the left;
  • without automatic offset capability, the aircraft flies the centerline;
  • it does not require ATC clearance and does not need to be reported;
  • reports remain based on the current clearance, not on the offset.

SLOP does not show up as a deviation

An aircraft applying SLOP reports the same fix it would report on the centerline. Up to 2 NM is not a navigation error and should not be questioned. What deserves attention is a lateral deviation of 5 NM, which triggers the ADS-C event contract29.

Deviations

Aircraft unable to comply with the clearance

If it cannot follow the clearance, or maintain the required navigation accuracy, ATC must be informed immediately30. On receiving the report:

  1. Identify what it cannot comply with.
  2. Confirm the concrete intention: which level, which heading, for how long.
  3. Protect separation before the previous minimum is infringed.
  4. Coordinate with the affected adjacent unit and record it.

Weather deviation

  1. Receive the request with the intended side and distance.
  2. Assess traffic in the lateral band and at adjacent levels.
  3. Clear it with an explicit limit: how many miles, for how long, with an instruction to report back on route.
  4. Reassess longitudinal separation, because the deviation changes the estimates.
  5. Request the revised estimate and coordinate with the adjacent unit.

Severe turbulence affecting level keeping triggers UNABLE RVSM DUE TURBULENCE31 and leads to considering suspension of RVSM in the area4.

Conflict between a deviation and traffic

In this order: level first, which is the fastest and most verifiable solution; then a Mach adjustment; then limiting the lateral extent cleared; and traffic information to both aircraft when nothing resolves it completely.

Require an explicit report of the return to the centerline with a revised estimate. Until then, keep the established protection.

  1. ICA 100-37, Art. 323. ↩

  2. AIP-Brasil, ENR 2.2, item 1.1. ↩↩

  3. AIP-Brasil, ENR 2.2, items 1.3 and 1.6. ↩↩

  4. AIP-Brasil, ENR 3.5, item 7.8.1, and ENR 2.2, item 1.12. ↩↩

  5. AIP-Brasil, ENR 3.5, item 6.4.1.1. ↩↩

  6. AIP-Brasil, ENR 3.5, item 6.2.2. ↩↩

  7. ICA 100-37, Art. 378, and CIRCEA 100-66, Art. 6° and Table 1. ↩↩

  8. AIP-Brasil, ENR 3.5, item 6.4.2.1. ↩↩

  9. CIRCEA 100-66, Arts. 7° and 8°. ↩↩

  10. ICA 100-37, Arts. 386 and 387. ↩

  11. ICA 100-37, Art. 362. ↩↩

  12. ICA 100-37, Art. 363. ↩↩

  13. ICA 100-37, Art. 366. ↩

  14. ICA 100-37, Arts. 364 and 365. ↩↩

  15. ICA 100-37, Arts. 330 and 331. ↩

  16. ICA 100-37, Art. 353, Table 4. ↩

  17. ICA 100-37, Art. 350, Table 3. ↩

  18. ICA 100-37, Arts. 337 and 382. ↩↩

  19. CIRCEA 100-66, Art. 4°, item VI. ↩

  20. ICA 100-37, Art. 377. ↩

  21. CIRCEA 100-66, Chart 1 (Quadro 1). ↩

  22. CIRCEA 100-66, Chart 3 (Quadro 3). ↩

  23. CIRCEA 100-66, Art. 10. ↩

  24. AIP-Brasil, ENR 3.5, item 9.5.2.6.2. ↩

  25. ICA 100-37, Art. 270. ↩

  26. ICA 100-37, Art. 271. ↩

  27. ICA 100-37, Art. 822. ↩

  28. AIP-Brasil, ENR 3.5, items 7.9.1 to 7.9.3.8. ↩

  29. AIP-Brasil, ENR 3.5, item 9.5.2.3. ↩

  30. AIP-Brasil, ENR 3.5, item 8.8.1. ↩

  31. AIP-Brasil, ENR 2.2, item 1.13. ↩