If as Russian authorities are claiming the Metrojet A321 that crashed in Egypt’s Sinai on Saturday — killing all 224 people on board — broke up in mid air, a great deal hangs on just how high the jet was when this happened.

The data published by Flightradar 24 shows that the jet was severely upset while in stable cruise at almost 31,000 feet. However, on advice, those abrupt changes in vertical speed would not have caused the structure of a properly maintained modern airliner to come apart, at least not immediately.

But they would have exceeded operational and design tolerances for negative and positive loads on the airframe, meaning that extensive inspections and repairs would be mandatory after it had landed.

However, Metrojet flight 9268 didn’t land, it struck the ground at high speed, apparently already in pieces, and while the main pieces of wreckage appear relatively close to each other, smaller debris is widely scattered.

There is no published data, as yet, regarding what happened to the A321 more than 20 seconds after the initial upset. Flightradar24 was unable to track it all the way to the ground, and that information should be retrievable from its flight-data recorder, which, together with the cockpit voice recorder, has been recovered from the wreckage.

Gyrations in the body of the falling jet could be expected to tear it apart under various scenarios. But if flight 9268 was, contrary to all current official advice, hit by a surface-to-air missile, the integrity of the airliner could have been destroyed much sooner than by the aerodynamic forces at work if the pilots had completely lost control for whatever reason.

That possibility is still of sufficient force to have caused major airlines to immediately heed a warning about the risks of missile strikes for the Sinai peninsula issued last November, which advised them not to fly over much of it at less than 26,000 feet.

There has been no evidence, for what that is really worth, of highly capable ground-to-air missiles like the Russian-made BUK, that destroyed Malaysia Airlines flight MH17 over east Ukraine on July 17 last year, killing 298 people, having been deployed in the Sinai peninsula.

But the wording of the safety notice about Sinai issued last November has suddenly, after 224 fatalities, focused the minds of airlines that regularly cross it, leading to them pulling their flights.

It needs to be kept in mind that any airliner that experiences a cabin depressurisation must rapidly descend to much lower than 26,000 feet to keep its passengers alive once the emergency oxygen supply runs out.

If the warnings and findings in the Dutch Safety Board report into MH17 are revisited, it is inexcusable for airlines to even think it is safe to fly over territory in armed conflict, where missiles are in use, on the basis that they might rarely have to descend to 13,000 feet or lower.

MH17 taught the industry (if it is capable of listening) not to trifle with passenger lives on the basis of the risks of such a malfunction being very small.

It seems that whatever happened to Metrojet 9268, the inconvenient and costly risks of taking over flights across disputed territory that were highlighted by the MH17 disaster are only being heeded after there are piles of torn bodies being collected from crash sites.

This isn’t good enough.