The Iranian air force’s museum-vintage P-3 Orion patrol planes still are airworthy, a recent flyby indicates.

On Nov. 11, 2019, a Lockheed P-3F Orion belonging to the Islamic Republic of Iran Air Force flew a low, close pass above the U.S. Military Sealift Command dry-cargo vessel USNS Alan Shepard and USS Normandy, an accompanying U.S. Navy cruiser.

Navy photos depict the unarmed, four-engine P-3 flying near Alan Shepard and Normandy while the vessels transited the Gulf of Oman, a narrow chokepoint between the Persian Gulf and the Indian Ocean.

The P-3s appearance underscores Iran’s ongoing work to maintain its increasingly aged military arsenal. Decades of sanctions have deprived Tehran of the opportunity to import new warplanes, warships and army equipment.

The Iranians instead have focused on maintaining and upgrading Western- and Soviet-sourced weaponry that for the most part pre-dates the 1979 Islamic revolution in the country.

At least when it comes to the P-3s, the maintenance efforts appear to be working. Iran bought six P-3Fs from Lockheed starting in 1973. The P-3 at the time arguably was the world’s leading maritime patrol plane. Its high speed and superb low-level handling allowed it to effectively hunt surface ships and submarines.

One of Iran’s P-3s, serial 5-8702, crashed in February 1985, according to Scramble, a Dutch aviation magazine. Another P-3F reportedly also was written-off in 1985, ostensibly leaving the IRIAF with just four of the patrollers.

But Scramble has found evidence of five P-3s remaining in the Iranian inventory. “So we believe there was no second write-off in 1985,” the magazine noted. “There might have been an incident, but the aircraft must have been repaired.”

All five extant P-3Fs have appeared in public in recent years. Serial 5-8705 is the plane that buzzed the American ships in November 2019. Sister plane 5-8706 appeared in May 2016. Serial 5-8701 last showed up in October 2009. Serial 5-8703 made its last major appearance in August 2008. Serial 5-8704 showed up in 2006.

Those dates aren’t the only times the P-3s have appeared in photographs or commercial satellite imagery. They’re just the most recent occasions when the planes’ serial numbers clearly have been visible, confirming their precise identity.

There are five P-3Fs. But Scramble asserted that just two, and possibly three, still are operational, typically flying from the IRIAF base at Shiraz. “Two aircraft are used as spare parts or are rotated through a maintenance program,” the magazine explained.

Analyzing some 90 Google Earth pictures (the first one is dated Oct. 7, 2003, the last one Aug. 31, 2019), we only see one moment that four P-3Fs were at Shiraz (June 24, 2009). One aircraft (most probably the same one) is noted since 2006 in a 100-percent fixed position next to the 71st [Anti-Submarine Warfare] Squadron hangar with a barricade of blocks in front of it. ...

Since June 2009, we see three, but in most cases two Orions parked at Shiraz. Clearly visible in 2013, the IRIAF encountered problems with their Orions, as between late March 2013 and late January 2014, two aircraft were seen outside at exact the same position.

We therefore assume that both aircraft were not operational/stored. Clearly both aircraft did not move throughout this period! In May 2014, we see some changes as a third Orion arrived at Shiraz. This aircraft was clearly repainted as it had a high-contrast color scheme compared to the other two aircraft that were stored throughout 2013 and early 2014 ... This aircraft must have been overhauled, most probably at Mehrabad.

Going back to P-3F next to the 71st ASW Squadron hanger. We assume this aircraft was cannibalized through the years (we can see the lack of engines, propellers, outboard ailerons and [magnetic-detector] boom). Strikingly, on the image from Aug. 31, 2019, it is clearly seen that this aircraft was on rebuild. Ailerons were attached again, but it still lacks propellers.

Nearly 50 years is a long time for a warplane to fly, especially when so many of its flights are over the ocean with its corrosive salt spray.

But the U.S. military routinely operates aircraft into their fifth decade or even longer. Given its lack of alternatives, Iran certainly will endeavor to keep its precious patrol planes flying for years or even decades to come.

David Axe serves as Defense Editor of the National Interest. He is the author of the graphic novels  War Fix, War Is Boring and Machete Squad.