Top IOSA Audit Preparation Consultancies for Airlines and ACMI Operators

IOSA registration is a filter. IATA members must hold it, many codeshare partners ask for it, and lessees increasingly check it before signing an ACMI contract with an operator they do not know. For a new airline or a wet lease operator moving into a new market, a failed or delayed audit can cost a season of work.

Timing matters right now. IOSA has been a risk-based audit since 2024, with the scope tailored to each airline's profile, safety data and audit history. Audits in 2026 use ISM Edition 18 Revision 1, and Edition 19 applies to audits from 1 January 2027. Airlines with an audit due next year should check their manuals against the new edition before booking a mock audit.

How we chose these consultancies

Each firm was checked on its own website this session. We kept consultancies that publish a specific IOSA preparation service, such as gap analysis, documentation work, mock audits or corrective action support, and that state where they work from. This is not a paid ranking. One caution: some IOSA audit organisations also sell preparation services. Read the conflict of interest rules in the IOSA Programme Manual before you hire the same firm for preparation and for the audit itself.

IOSA findings often trace back to training records and subcontractor oversight. Our guides on auditing crew training records before an ACMI lease and auditing an ACMI training provider cover two of the usual weak spots.

Top IOSA audit preparation consultancies

1. IATA Consulting

IATA Consulting runs IOSA and ISSA preparation with consultants who are all IOSA accredited auditors. The published method has three steps: an in-house one-week IOSA Airline Auditor Course followed by a readiness assessment and roadmap, a full mock audit with a gap analysis, corrective action plan and training needs assessment, and then on-the-job coaching plus review or drafting of operational manuals. Fit: airlines that want the programme owner's own experts.

2. mba Aviation

mba Aviation was founded in 1992 as Morten Beyer and Agnew and is best known for aircraft valuations. It was accredited by IATA as an IOSA Audit Organization in 2004, says it is one of only six such audit companies, and reports more than 450 IOSA audits worldwide. Its safety team also offers gap analysis, corrective action development, manual writing and IOSA or ISSA preparation. Because it audits as well as advises, confirm which role it will play for your airline at the outset.

3. GHS Aviation Group

GHS Aviation Group is based in Manassas, Virginia. Its IOSA preparation service covers a gap analysis, manual revisions, training on how to read and audit the ISARPs, an objective readiness assessment, a corrective action work plan and help completing an accurate Conformance Report. GHS recommends starting at least six months before the on-site audit.

4. Aero Support Group

Aero Support Group lists offices in London, Dubai and Istanbul and a network of more than 36 IATA and ICAO qualified consultants from 12 nationalities, including former IATA and ICAO auditors. Its IOSA work covers gap analysis against the current ISM, documentation development, mock audits, staff interview preparation, Conformance Report support and post-audit corrective action plans. It also sells a retained subscription, IOSA RADAR, with quarterly compliance reviews and readiness checks starting 180 days or more before the audit.

5. AEROTHRIVE

AEROTHRIVE is headquartered in Hamburg, Germany, with a Middle East base in Dubai. Its IOSA support is sold in modules: initial IOSA training, an IOSA gap analysis, help closing non-conformities, a final implementation gap analysis and health check, and on-site support during the real audit. Fit: airlines that want to buy only the stages they cannot cover in-house.

6. NAAC

National Aviation Assurance and Compliance (NAAC) is an Australian firm offering IOSA and ISSA preparation. The service includes a gap analysis of management systems and operational activities, action plans, and support implementing corrective actions through to IOSA registration. NAAC also runs operational and safety reviews of aircraft operators for mining, oil and gas clients, which is useful for charter operators that serve the resource sector.

7. General Consulting Services (GCS)

General Consulting Services is based at the Meydan Grandstand in Dubai. It provides IOSA preparation, gap analysis, team building, implementation and follow-up, and offers the same structure for ISAGO, EASA, FAA, civil aviation authority and ICAO USOAP audits. Fit: Middle East and African carriers that need one adviser across several audit regimes.

What a good IOSA gap analysis should deliver

A gap analysis is only useful if it leads to work your team can finish before the audit. Ask for a deliverable that lists every applicable ISARP, the evidence the consultant reviewed, the finding level and a named owner for each corrective action. It should also separate documentation gaps, which are quick to close, from implementation gaps, where the manual is right but the operation does not follow it. Auditors find the second kind in interviews and records.

Three areas cause repeat trouble for ACMI and charter operators. The first is oversight of outsourced functions, such as ground handling, maintenance and training providers, where IOSA expects documented audits of each supplier. The second is training records, especially for crews who rotate between lessees. The third is the safety management system: hazard reports, risk assessments and safety performance indicators need data behind them, not just a policy. Tools covered in our list of aviation safety management software providers can help with the record keeping, but the process has to exist first.

How to use this list

Ask each firm three things before signing. First, who will actually do the work, and are they current IOSA auditors or former ones. Second, whether the gap analysis is against Edition 18 Revision 1 or Edition 19, since that decides how much rework you face in 2027. Third, what happens after the mock audit: a report only, or hands-on help closing findings.

For ACMI operators, IOSA status is also commercial. Lessees screening capacity on the ACMIWORLD marketplace (Access, Listing and Request are paid subscriptions) can filter for operators with current registration, and operators that hold it should say so in their listing.

Build the timeline backwards from the audit date. The mock audit should sit far enough ahead that corrective actions have time to produce evidence in records, not just revised manuals. A finding closed on paper the week before the audit, with no operational records behind it, is usually raised again by the auditors. Budget for consultant travel, internal staff time and any manual translation, which are often missing from the first quote.

FAQ

How long does IOSA preparation take?

For a first registration, plan on six months or more from gap analysis to the on-site audit. Renewals are shorter if findings from the last audit were closed properly.

How often is an IOSA audit carried out?

Registration lasts two years, so in practice an airline is audited every two years, with the renewal audit timed so findings can be closed before registration expires.

What changes with ISM Edition 19?

Edition 19 applies to audits from 1 January 2027. Airlines should compare their documentation against the new edition and the current risk-based audit approach before their next mock audit.

Do lessees require IOSA for ACMI contracts?

Not always, but many airlines require IOSA or an equivalent audit before wet leasing in capacity, especially when the lessee is an IATA member. Without it, expect a longer due diligence process.