As the domino-chain grounding of the Boeing 737 Max and its gradual patchwork rehabilitation have revealed, unanimous agreement that air safety is paramount does not necessarily translate into a harmonised approach to delivering it.

When the European Union Aviation Safety Agency grounded the Max in March 2019, the US FAA initially resisted. And EASA is only just preparing to lift its ban, having maintained it for more than two months despite the FAA’s recertification of the aircraft in November last year.

This contrast exposes a transatlantic disparity over the appropriate course of action which echoes a situation that emerged in a previous mass grounding – that of the McDonnell-Douglas DC-10 more than four decades ago – and raises questions as to the degree to which a central principle of ICAO is being undermined.

The FAA suspended the DC-10’s type certificate in the early hours of 6 June 1979 and terminated the individual airworthiness certificates for each US-registered airframe. FAA administrator Langhorne Bond subsequently issued a special regulation, SFAR 40, banning all foreign-registered DC-10s from US airspace.

This decision followed the fatal loss of an American Airlines DC-10-10 at Chicago O’Hare on 25 May, after an engine separated from the jet on take-off. The crash further battered the reputation of the DC-10, already marred soon after service entry by explosive decompression accidents involving an American DC-10-10 over Windsor, Ontario, in 1972 and a Turkish Airlines DC-10-10 in Paris in 1974.


After the FAA decision several foreign regulators provisionally suspended individual airworthiness certificates for DC-10s and, during the week of 11 June, European authorities and DC-10 operators discussed the conditions under which the aircraft could be returned to service.

Laker DC-10-c-The Flight Collection

Source: The Flight Collection

UK carrier Laker Airways was among DC-10 operators affected by the grounding

UK operators British Caledonian and Laker Airways had been among carriers forced to ground their DC-10s after the UK Civil Aviation Authority suspended the aircraft’s certificate of airworthiness.

Newly-appointed UK junior trade minister Cecil Parkinson told parliament that the suspension was a “direct consequence” of the FAA’s “courageous” decision, made under “considerable” commercial pressure, pointing out that the CAA was “substantially influenced” by type certificates issued by the country of manufacture.

But parliamentarians sought assurances that the CAA would conduct independent analysis of the aircraft’s airworthiness, and not rely on manufacturer’s technical information, suggesting to Parkinson that if the FAA had grounded the DC-10 after the Windsor accident, and addressed the type’s cargo door design, the fatal Paris crash would have been avoided.

“On the question of an independent consideration, when the certificate of airworthiness is granted, the facts and the technical details which have been discovered by the country of origin are made available to the CAA and form the main basis of the decision that is taken,” Parkinson said.

“The CAA needs to have access to the findings of the FAA before it can arrive at an independent decision on this matter. It will need to know what the FAA is finding out and use its own judgement in arriving at a decision.”

Evidence of a transatlantic split emerged after European authorities and 13 carriers met in Zurich a week later and, on 19 June, the CAA and other European regulators restored airworthiness certificates to DC-10 fleets.

Under-secretary for trade Norman Tebbit, himself a former BOAC pilot, was asked the following day in parliament, by his opposite number John Smith, about apparent criticism of the CAA decision by the FAA.

“Does he not think that it is most unsatisfactory that there now appear to be competing judgements on the safety of the DC-10s, with the Civil Aviation Authority and some other European authorities in open dispute with the Federal Aviation Administration?” said Smith.

The FAA had “expressed its dismay” over the European decision to give the DC-10 a “clean bill of health” before its inquiries had concluded, added parliamentarian Stanley Clinton-Davis, describing the dispute as “completely unprecedented” and stressing that passengers who held “strong doubts” about the DC-10 would be “pressed” into boarding aircraft they did not want to fly.

Tebbit replied that conditions and procedures in the UK and USA were “different”, that the CAA had taken the advice of the airworthiness requirements board and casting doubt on its competence or integrity was not “proper”.

“I do not question the wisdom of the Americans,” he added. “That is a matter for their authorities. We have acted properly in relation to ours.”

Tebbit was also asked by a parliamentary colleague whether European aviation regulators, which were then loosely associated under the Joint Airworthiness Authorities, should be strengthened in order to reinforce confidence in them and ensure that they were respected by the FAA – an early hint of the thinking that would eventually lead to the creation of EASA.


After European authorities cleared the DC-10 for flight a delegation of European Civil Aviation Conference members met with US representatives in Paris, on 25 June, to request a lifting of the SFAR 40 ban which prevented their aircraft operating in US airspace.

The European side argued that, under Article 33 of the Chicago Convention, the certificates of airworthiness issued to the DC-10 had to be recognised by other ICAO contracting states, and no evidence had been presented by US authorities to suggest that European requirements fell short of minimum standards.

But the US representatives refused the request, maintaining that the US position was consistent with international obligations and domestic law.

After assessing the findings of inquiries into DC-10 type certification and maintenance procedures, the FAA rescinded its suspension on 13 July 1979, and issued several directives detailing inspections of systems and structures on the aircraft.

But by this point the transatlantic disagreement over SFAR 40 had already escalated into a legal dispute, led by British Caledonian which had filed a court petition in Washington on 27 June. Lufthansa, Swissair and Belair filed a similar petition on 11 July having jointly failed to convince the FAA to remove its restriction.

Although the FAA’s subsequent restoration of the DC-10’s type certificate, and its lifting of SFAR 40, resolved the immediate operational issues for European carriers, the consolidated petitions proceeded after the court denied an FAA motion to have them dismissed for being academic.

“As long as the [FAA] asserts that [it] has the legal authority…to disregard valid airworthiness certificates issued by nations with whom the USA has entered into binding aviation agreements, these nations reasonably can expect to be subjected to the same action at some time in the future,” the court ruled.

It also suggested that, because the administrator “at no time questioned” whether the foreign governments met minimum ICAO safety standards, refusal to rescind SFAR 40 in the wake of foreign revalidation of the DC-10’s airworthiness “would appear to have violated” Article 33.

The court was not convinced by other FAA arguments on the matter, and ultimately concluded that the administrator’s issuing SFAR 40 “violated various multilateral and bilateral civil aviation agreements”, and that it “must be set aside”.


But if the DC-10 episode had stress-tested the ICAO principle of mutual recognition set out in Article 33, the rapid cascade of 737 Max groundings in response to a second fatal Max accident in March 2019 effectively fractured it.

While any national regulator has the right to ground aircraft on its registry, several went far beyond this right despite the FAA’s not having taken any action against the 737 Max. Authorities in Australia, Singapore, India, Canada were among those which imposed a blanket ban on domestic and foreign Max operations, along with EASA.

At an ICAO civil aviation legal advisers’ forum in Singapore, held two months later, FAA assistant general counsel Jeffrey Klang questioned whether individual countries’ regulatory actions to prohibit Max operations had been lawful under Article 33, given that these actions had been taken prior to the conclusion of investigations and without any specific deficiency having been identified in the aircraft.

This spurred discussion on the tricky issue of taking action in the interests of safety in a way which is legally acceptable, whether national laws take precedence over international treaties, and whether circumstantial evidence that safe aircraft operation cannot be guaranteed is sufficient justification for action.

According to the proceedings of the forum, the participants also acknowledged that the pre-emptive measures by various regulators had “played a part in raising the level of response” by US authorities and Boeing.

“It was understood that the issue of considering the proper regulatory response to the [737 Max] accidents was continuing and would be the subject of future discussions particularly after the outcomes [and] results of investigations are known,” the proceedings add.

American 737 Max-c-American Airlines

Source: American Airlines

US carriers were cleared to restart 737 Max operations in November 2020

The FAA’s order of 18 November last year, rescinding the Max grounding, notably states that it will apply ICAO’s Article 33 to foreign-registered Max aircraft and restrict access to US airspace if the foreign aviation regulator does not require conformance to the Max’s design modifications or an alternative achieving an equivalent level of safety.

EASA has not automatically followed the FAA rescission, keeping its own prohibition in place for another two months.

No operators appear to have tested the precedent affirmed by the DC-10 ruling – that under Article 33 the FAA’s certificate of airworthiness for the 737 Max must be recognised by other ICAO member states – by attempting to fly a US-approved 737 Max to the European Union.

The pandemic, of course, might have suppressed any appetite for a legal challenge this time around, and the co-operative efforts to restore confidence in the Max suggest interest in avoiding any widening of the regulatory split.

But once the 737 Max has been brought back from exile and re-integrated into the world’s airline schedules, and once a sense of normality has been restored to the air transport system, the argument over respecting Article 33 – and the crucial tenet of trust contained within it – will remain, an awkward unresolved aspect of the whole sorry saga.