Ask most people what RVSM is and they will tell you it is an operational approval — a box the operations department ticks so the fleet can fly the busy levels between FL290 and FL410. They are half right. The operator does need a specific approval under Part-SPA of Regulation (EU) 965/2012. But read SPA.RVSM.105 and you find that approval rests on two foundations the operations department does not control. To obtain it, the operator must provide evidence that “the RVSM airworthiness approval has been obtained” and that “procedures for monitoring and reporting height-keeping errors have been established”. And when EASA sets out what the application file has to contain, AMC1 SPA.RVSM.105 lists, under the heading Continuing airworthiness: “Aircraft maintenance programme and continuing airworthiness procedures in support of the RVSM operations.”

The approval itself belongs to the operator — that is worth being precise about, because it is the operator whose name is on it and the operator who reports height-keeping errors under SPA.RVSM.115. But the operator cannot obtain that approval, or keep it, without the maintenance programme and the continuing-airworthiness procedures. That work is yours, and it sits in the application file.

It matters because Reduced Vertical Separation Minimum gives aircraft just 1,000 feet of vertical space where there used to be 2,000. The entire system depends on every aircraft holding its assigned level with extraordinary precision, and that precision is not bought once at certification — it degrades, quietly, through ordinary wear and ordinary maintenance events. A static port that sits a fraction proud after a repair. A skin panel that is slightly wavy near that port. A static line that was not leak-checked after a disconnect. An altitude-hold that has drifted. None of those are operational issues. Every one of them belongs to continuing airworthiness and maintenance.

The airworthiness criteria themselves now sit in CS-ACNS, Subpart E, Section 2 — Reduced Vertical Separation Minimum, at points CS ACNS.E.RVSM.001 to .035. The older JAA Temporary Guidance Leaflet No 6 has not disappeared, and it is worth knowing why: CS-ACNS Issue 5 still records that “altimeters compliant with JAA TGL No 6 are an approved and acceptable means of compliance for the altitude source”, so legacy type certificates and RVSM data packages that reference it remain valid on that point. Other legacy references have been retired — CS-ACNS names AMC 20-28, JAA TGL-10 and CM-AS-002 Issue 2 as obsolete — but TGL 6 is not among them.

What the maintenance duties actually say

This is the part that rarely makes it into an operations briefing. AMC1 ACNS.A.GEN.010(b), on instructions for continued airworthiness, sets out four items to which “attention should be given”:

• All RVSM equipment maintained in accordance with the component manufacturers’ maintenance instructions and the performance criteria of the RVSM approval data package.
• Repairs not covered by approved maintenance documents that may affect the integrity and accuracy of the altimeter system — the AMC gives the examples itself: “those affecting the alignment of pitot/static probes, repairs to dents or deformation around static plates” — “should be subject to a design review which is acceptable to the competent authority”.
• “Airframe geometry or skin waviness checks should be performed following repairs or alterations which have an effect on airframe surface and airflow.”
• The maintenance and inspection programme for the autopilot should ensure continued accuracy and integrity of the automatic altitude control system.

AMC3 SPA.RVSM.105 then goes further on the continuing-airworthiness side, requiring a process to assess “any modification or design change which in any way affects the RVSM approval”, to evaluate repairs that may affect the integrity of the continuing approval, and to maintain airframe geometry “for proper surface contours and the mitigation of altimetry system error”. It also notes that additional training may be necessary for continuing airworthiness and maintenance staff — highlighting aircraft geometric inspection techniques, test equipment calibration and use, and any special procedures introduced for the RVSM approval. Note the wording: this is an acceptable means of compliance offering areas that may need attention, not a mandated syllabus.

This is why, in our experience, when an aircraft drops out of RVSM service it is rarely the crew that caused it and rarely the crew that can fix it. The paperwork sits with operations; the cause usually sits in the hangar or the technical records. Understanding where the line falls — the operator holds the approval, the CAMO and the Part-145 organisation hold it up — is the first step to getting RVSM right.

Two points worth carrying into your own procedures. First, the reporting thresholds are the operator’s, under SPA.RVSM.115: a total vertical error of ±90 m (±300 ft), an altimetry system error of ±75 m (±245 ft), or an assigned altitude deviation of ±90 m (±300 ft), reported to the competent authority within 72 hours with an initial analysis of causal factors. Your procedures are what make that report possible and, more importantly, what stop it being needed. Second, RVSM airspace is defined in SPA.RVSM.100 as the 300 m (1,000 ft) separation minimum “between flight level (FL) 290 and FL 410, inclusive” — a point amended by Regulation (EU) No 965/2012 as recently as 2024, so it is worth checking you are working from current text. The consolidated rules, AMC and GM are published in the EASA Easy Access Rules library.

If you are building or amending the procedures this article describes, our guides on how to write a CAME and on the CAMO management system under CAMO.A.200 cover where continuing-airworthiness procedures like these belong in the exposition.

Check out our RVSM course for Part-CAMO & Part-145 personnel: