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Passengers injured as US fighter jet comes close to Iranian plane

The Iranian plane, belonging to Mahan Air, was heading from Tehran to Beirut on Thursday when the pilot staged a safety manoeuver, in an incident that Iran's Foreign Ministry said would be investigated. ... Central Command spokesman, said the F-15 "conducted a standard visual inspection of a Mahan Air passenger airliner at a safe distance of about 1,000 metres (3,280 feet) from the airliner this evening". "The visual inspection occurred to ensure the safety of coalition personnel at Tanf garrison," ... "Once the F-15 pilot identified the aircraft as a Mahan Air passenger plane, the F-15 safely opened distance from the aircraft." He added the intercept was carried out in accordance with international standards.

My questions are the following:

  • Is there such thing as "standard visual inspection" at all? Is it normal in such circumstances? What's its purpose and how necessary is it?
  • Isn't there any other method to this end, instead of "visual inspection"?
  • Is "1,000 metres" distance considered "safe" for such conditions?
  • In what conditions do passenger airliners stage a "safety manoeuver" like this?

Update

  • Are there similar incidents? Some military aircraft approaches an airliner to "inspect" it and see if it has really passengers on-board, in a manner they consider "safe" and "in accordance to international standards". The airliner considers this "unsafe" and stages a "safety maneuver", leading to injuries.
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Is there such thing as "standard visual inspection" at all? Is it normal in such circumstances? What's its purpose and how necessary is it?

Visual inspections are very common. Military pilots train regularly to visual inspections of other aircraft, and typically close to within 25-50 feet of another (cooperative) aircraft to do so. At a 25-50 foot range, you can easily see if an aircraft panel is missing or even loose/flapping in the wind. Having said that, there is no "universal standard" for what comprises a safe and normal visual inspection and distances and closure rates that are considered safe may vary depending on your experience and aircraft type.

Isn't there any other method to this end, instead of "visual inspection"?

According to the researcher quoted in the article, the F-15 may have been attempting to see if the airliner had passengers onboard. You would need to close to well within 1/4 of a mile (1500 feet) to have any hope of determining that with a naked eyeball. If the F-15 had a camera system (common), that may have allowed them to remain farther from the airliner, however.

Is "1,000 metres" distance considered "safe" for such conditions?

1,000 meters is likely very safe, and it's really far away compared to how military pilots are trained. However, what matters is how the pilots of the airliner felt. They are likely not military trained, and were probably unaccustomed to seeing another aircraft that close to their airplane.

The article is a little misleading when it implies that aircraft typically maintain at least 600 meters separation to avoid hitting each other. That number (600 m), refers to two aircraft on different altitudes that not aware of the other's presence. For a military pilot who has a radar and is looking at an airliner, 600 m is not required at all.

In what conditions do passenger airliners stage a "safety manoeuver" like this?

Here's where we get into some speculation. I'm not sure what the article is referring to, but I suspect that the airline pilots were responding to a TCAS RA (Traffic Collision and Avoidance System- Resolution Advisory) generated by the F-15's proximity and closure rate to the airliner. In this case, the airline pilots may have been presented with a "Climb" or "Descent" command by the computer, which would explain their abrupt climb and descent.

Whether or not the climb they undertook should have been so violent that passengers were bounced out of their seat and onto the floor is a matter of the pilot's judgement and speculation without knowing exactly what happened between the two aircraft.

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    $\begingroup$ It seems like the question you're really asking is, "who is at fault here?" If you're willing to accept speculation, in my professional opinion: the airliner pilots wildly over-reacted. I would compare the airliner's reaction to a taxi driver who sees a police car turn on his lights as he drives across a parking lot toward the taxi. The taxi then swerves wildly to "avoid" the police car and injures its passenger. It's not necessary - the police car was never going to hit the airliner. $\endgroup$ – Tyler Jul 29 at 19:48
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    $\begingroup$ It should be mentioned that sending fighters to intercept an airliner that stopped communicating to check whether the airliner has a problem and try to re-establish communication is fairly common. Most of the time the pilots simply set their radio incorrectly and quickly fix that error when they see the fighter, but if there is a bigger problem, the fighter can guide the aircraft to suitable airport. In this case the reason was slightly different, but the procedure used was basically the same, so it should be considered standard in that sense. $\endgroup$ – Jan Hudec Jul 29 at 20:02
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    $\begingroup$ I find the claim that it was trying to check whether there are actually passengers rather difficult to believe, for two reasons: 1. the fighter didn't come close enough to really see and 2. even if there were few or none, it could still be a legitimate civilian flight, especially in this day of travel restrictions due to COVID. I think they were just verifying the type, tail number and livery match the plane they expected. $\endgroup$ – Jan Hudec Jul 29 at 20:11
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    $\begingroup$ avherald reports that “the Mahan crew reacted to a TCAS resolution advisory to climb.” If that is confirmed, it was at least partly fault of the fighter pilot – they are supposed to switch their transponder to a mode that does not trigger TCAS when approaching the target and use their radar for separation instead exactly to avoid provoking it to abrupt manoeuvres. $\endgroup$ – Jan Hudec Jul 29 at 20:17
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    $\begingroup$ @Tyler, yes, TCAS RA indeed does not require bouncing passengers around and other crews react to them all the time without causing any injuries in the cabins. But every accident is a chain of issues and the fighter pilot not switching their transponder correctly for that kind of intercept is one of them. $\endgroup$ – Jan Hudec Jul 30 at 5:46

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