OFAC blocked 36 targets on 8 September. The wind-down licence names three of them

The US Treasury designated 27 Iranian airlines on 8 September, along with eight companies and one man outside Iran. Treasury's headline says the action grounds Iranian airlines.

The nine outside Iran were not designated for supporting the 27 airlines. Each was designated, in Treasury's words, for having materially assisted or provided goods or services to Mahan Air, which was already blocked. Treasury says that in summer 2026 Mahan Air took delivery of at least three Boeing 777s, routed through the UAE and Oman, with ECT Aviation Support LLC and Sky Phoenix serving as intermediaries.

The names came 15 days after OFAC made aviation a sanctionable sector and named no airline. We wrote at the time that a determination gives you a population to investigate rather than a name to screen. The population took 15 days to become a list.

Counter Terrorism General Licence 37, issued the same day, runs to four paragraphs. Paragraph (a) authorises the transactions needed to wind down business with blocked persons through 12:01 a.m. Eastern Daylight Time on 23 September 2026, and then lists who those persons are:

1. ECT Aviation Support LLC
2. S Sistem Lojistik Hizmetler Anonim Sirketi
3. Mes Cargo Transportation Tourism and Foreign Trade Limited Company
4. Any entity the three own 50 percent or more of, directly or indirectly

Three names, out of 36 parties blocked that day. The licence adds a condition that is easy to miss: money owed to a blocked person is not paid over; it goes into a blocked, interest-bearing account in the United States.

Iran General Licence DD, issued alongside, does not cover dealings with the newly blocked. It covers activity that was permitted until 8 September. OFAC suspended four items under the Iranian Transactions and Sanctions Regulations that day, and they are not the same kind of thing:

The middle row is different in kind, and it is the row most likely to be misread. Section 560.528 never authorised anything by itself; it says specific licences "may be issued on a case-by-case basis" for the safety of civil aviation. Suspending it closes that door to new applications. General Licence DD does not mention it because there was no general authorisation there to wind down; a specific licence already issued runs on its own terms, and OFAC's notice says nothing about licences already in hand.

Row three explains why General Licence DD has nothing to do with the 27 airlines: 560.529 only ever covered non-Iranian carriers, and it excluded blocked persons.

Nothing about a counterparty changed when those four were suspended. No name entered a list, so no screening run anywhere returned a different answer. A screening system reads prohibitions, not permissions. If your only control for whether an activity is still allowed is a no-match result, this is how it fails: the check passes and the activity is no longer allowed.

ECT AVIATION SUPPORT LLC is registered in the UAE. ECT AVIATION SUPPORT LTD is registered in the United Kingdom. Both were blocked on 8 September, and only the first is named in Counter Terrorism General Licence 37.

That is not the end of it. The licence's fourth line covers any entity the three named companies own 50 percent or more of, and Treasury's press release says the UK company "is wholly owned by ECT Aviation Support UAE". So the London company has the same 23 September deadline as the UAE one, reached through an ownership clause instead of by name.

Neither document is enough on its own. The deadline is in the licence, not the press release. The ownership link is in the press release, not the licence. And a file that recorded ECT Aviation Support — SDN match cannot tell you which of the two companies it meant, because the names differ by two letters.

OFAC listing a UK company does not put it on the UK Sanctions List, which is kept by a different government. The US designation still reaches a European firm, because a payment in dollars clears through a US bank whatever the nationality of the parties to it.

Twenty-seven designations do not make screening twenty-seven units harder. What decides the cost is how much the new names resemble each other and what was already in the file, and these resemble each other a great deal. Fifteen of the 27 primary names contain Airlines and three more end in Airways. Three carry Kish, the name of an Iranian island: KISH AIRLINES, FLY KISH AIRLINES and PARS OGHYANOUS KISH COMPANY. The first is a complete substring of the second, so a query for one returns both. An analyst then has to work out which of the two legal persons the hit refers to before the alert can be closed.

We counted the overlap in our own production copy of the OFAC data on 9 September. Each token below is a word taken from one of the new names. The first count is every record in the whole file that contains it, old and new together; the second is how many of those arrived on 8 September.

More than half of all OFAC records containing AIRLINES arrived on a single Tuesday. The 27 in that row is a coincidence: it counts records, and twelve of them are older than this action. MEHR and PERSIA are in the table because Mehr Airways and Fly Persia Airlines are new, and both words are common in Iranian company names, so a query for either pulls in records that have nothing to do with it.

The oldest trap is IRAN AIR. Search our copy of the file for that string and six entries come back, published across 18 years under six programme tags:

Four of the six are not airlines. One is an air force. One, Safiran Airport Services, is on the list under a Russia programme and matches only because the eight characters of IRAN AIR sit inside SAF-IRAN AIR-PORT and mean nothing there. A hit on Iran Air is not a finding. It is the beginning of one.

A stricter threshold would not help either: IRAN AIR is an exact substring of all six names, and an exact substring survives any threshold. Read the entry, not the score, and store which entry the match was against, so nobody has to solve the same alert twice.

The 27 airlines carry [IFSR] and [IRAN-EO13902]. The nine parties outside Iran carry [IFSR] and [SDGT]. Every one of them is blocked, and it would be easy to file all 36 the same way.

The tag is the legal authority, and it limits which licence can reach which party. Counter Terrorism General Licence 37 authorises transactions otherwise prohibited by the Global Terrorism Sanctions Regulations, 31 CFR part 594, which is why it can name [SDGT] companies and could not have named an airline that carries no [SDGT] tag. It does not name the other five [SDGT] parties either. The tag tells you which licence could reach a party; only the licence tells you which one does.

The tag is also asked for later. If you are holding money or property of a blocked person, 31 CFR 501.603 requires you to report, for each item, the sanctions programme and the order it was blocked under. A file recording only that a name matched the SDN List cannot produce that a year afterwards, and rebuilding it from whatever the list says by then is weaker evidence.

1. Re-screen every counterparty that touches aircraft: freight forwarders, ground handlers, charter brokers, lessors, travel agencies, aviation insurers. Re-screen the whole book rather than spot-checking the names that made the news.
2. Separate the two ECT entities by company number, not by name. Both have the 23 September deadline, the UAE one by name and the UK one through the ownership clause, but your file has to show which company you dealt with.
3. Put 23 September in the calendar, with an owner's name against it. Anything relying on Iran General Licence J-1, on overflight payments under 560.522 or on bunkering under 560.529 stops at 12:01 a.m. Eastern time that day.
4. Pull any specific licence issued under 31 CFR 560.528 and read its expiry. OFAC suspended the policy of issuing new ones on 8 September, and General Licence DD does not extend anything under that section.
5. Check ownership. Under OFAC's 50 percent rule, a company owned 50 percent or more, directly or indirectly, individually or in the aggregate, by one or more of the 36 is blocked as well, and need not appear on any list. ECT Aviation Support Ltd is the worked example in this action.
6. Store the programme tag with the match, not just the fact of a match: which entry, which tag, which list version.

All 36 entries were in the production data on 8 September, Washington time, the same day OFAC published them. The lists are monitored and refreshed automatically, around the clock, across OFAC, the EU, the UK, the UN and the rest of the source register, so a new designation reaches your screening result without an import step, a vendor sync, or anyone reading the news first.

This is a report of what the US Treasury published on 8 September 2026, of what three OFAC licence documents say, and of what our own copy of the OFAC data contained on 9 September. It takes no position on the merits of any designation.

These are US measures. An EU or UK obligation, if there is one, comes from an EU or UK instrument you have to check separately. We have not published a count of how many of the 36 appear on those lists, because the exact-name probe that would produce one is the method this post argues against. A designation blocks the party named and, through the 50 percent rule, entities it owns half or more of; it does not block everyone who ever dealt with them.

And the counts here are counts of list entries, not of aircraft or of companies still flying. Treasury's headline is 27 airlines. OFAC's file shows 36 new rows, because the nine parties outside Iran are rows too.