The Sepehran Airlines Nose Gear Collapse, the Mashhad Runway Excursion, and What Every Landing Teaches Us About the Moment Before Touchdown

A Sepehran Airlines Boeing 737-500 veered off the runway at Mashhad International Airport in northeastern Iran following a nose gear collapse on landing. Runway excursions rank among the top three causes of fatal accidents in commercial aviation globally, and this incident adds to a persistent pattern that investigators, regulators, and front-line pilots have been working to break for decades.

What Happened at Mashhad

The aircraft landed and failed to complete a normal rollout. It departed the paved surface - a veer-off - and the nose gear collapsed. The airliner came to rest off the runway.

As of this writing, Iranian aviation authorities are still working to confirm passenger counts and injury figures. AeroTime broke the story. The nose gear collapse is confirmed. The sequence of events - which failure led to which - remains an open question for the investigation.

The Aircraft: Boeing 737 Classic

The 737-500 is part of the 737 Classic family, the second generation of Boeing’s 737 line. It entered service in 1987, and production ended in 1999. The youngest of these airframes are now pushing 27 years old. The oldest are approaching 40.

The 737-500 was popular with regional carriers for good reasons: it seats roughly 100 to 130 passengers and serves routes that the larger 737-400 couldn’t serve economically. The Classic series has a long and largely solid safety record. But any aircraft operating on aging components carries risks that a well-supported, younger airframe does not.

Iran’s Aviation Maintenance Constraint

Sepehran Airlines has operated the 737 Classic for years, and the broader context of Iranian civil aviation is inseparable from any incident involving an Iranian carrier.

Decades of international sanctions have severely restricted Iranian carriers’ access to Western aircraft, spare parts, and maintenance support. The aircraft flying in Iranian airspace are often older, and keeping them airworthy under those conditions is genuinely difficult. Replacement parts that are routine procurement items for carriers in other parts of the world become multi-year logistical problems.

This isn’t an excuse. It is context. And context is what separates a headline from an understanding of why something happened. The principle applies universally: age is manageable; age combined with deferred maintenance is not.

Runway Excursions: A Persistent Top-Three Killer

The Flight Safety Foundation, the FAA, and ICAO all track runway excursions as a major safety category. The Flight Safety Foundation classifies runway excursions as one of the top three causes of fatal accidents in commercial aviation, globally and consistently.

A runway excursion is any event where an aircraft departs the paved surface during takeoff or landing. That includes veer-offs (departing the side of the runway) and overruns (departing the end). The majority of excursions happen during landing, not takeoff.

The contributing factors documented across years of data fall into a short list: unstabilized approaches, excessive speed at touchdown, contaminated runways, crosswind, brake or tire failure, and structural failure of landing gear components.

How a Runway Excursion Begins

The excursion rarely begins at the moment the aircraft departs the pavement. The chain of events starts earlier - often much earlier.

The stabilized approach concept exists because accident data and simulator research show that crews arriving at the threshold outside stabilized parameters are significantly more likely to have a bad outcome. The parameters are specific: stable configuration, on-speed, on-centerline, with appropriate power, by 500 feet AGL in visual conditions and 1,000 feet AGL in instrument conditions.

The Flight Safety Foundation’s Approach and Landing Accident Reduction (ALAR) toolkit, in circulation since the late 1990s, documented that the majority of approach and landing accidents were preceded by approaches that were unstabilized by those gates.

The correct response to being outside stabilized criteria at those gates is a go-around, every time, without discussion. A go-around costs time, a small amount of fuel, and a radio call. It provides another approach with the energy and configuration the landing requires.

Crews are historically reluctant to execute go-arounds. Schedule pressure, social pressure, and the cognitive dissonance of admitting an unstabilized approach when the runway looks long and the weather looks fine - all of it is human, and none of it is rational. The stabilized approach call is hardest to enforce precisely when everything seems acceptable. That is when the discipline has to be strongest.

What This Means for General Aviation Pilots

The nose gear on a jet transport is a highly stressed component. Every landing cycles it through compression loads, side loads from crosswind or directional deviation on touchdown, and the drag of the nose wheel contacting the pavement. Over thousands of cycles, metal fatigues, seals wear, and hydraulic systems degrade. Maintenance is designed to catch the trend before it becomes a failure - but it catches most of it, not all of it.

The same principle applies to piston singles and light twins. The shimmy damper, the nose gear strut, torque links, tow bar fittings - these are consumable components. The annual inspection is meant to identify the trend. Between annuals, the preflight walkaround is the last line of defense.

A strut that’s running low, shimmy that wasn’t there before, play in the nose wheel that has increased - these are signals. The preflight is the moment to catch them. The runway at 60 knots with the nose coming down is not.

Investigation Transparency and Global Safety

Iranian aviation authorities will lead the investigation. ICAO will likely be involved. Whether findings become fully public is uncertain, given the political environment around Iranian civil aviation.

This matters beyond Iran. The entire Safety Management System (SMS) framework is built on the idea that lessons from one incident prevent the next one elsewhere. The NTSB operates one of the most transparent accident investigation processes in the world - reports, docket materials, and probable cause findings are all public record, going back decades. That transparency is a feature. It is how the safety system learns and improves.

Findings that remain locked within a single country’s investigation files do not improve safety anywhere else.

Key Takeaways

A Sepehran Airlines Boeing 737-500 veered off the runway at Mashhad International Airport following a nose gear collapse; the investigation into cause and sequence is ongoing.
Runway excursions are a top-three cause of fatal accidents in commercial aviation globally, with the majority occurring during landing.
Iran’s decades of international sanctions have severely constrained access to aircraft parts and maintenance support, creating a unique risk environment for its carriers.
The stabilized approach is not a suggestion - it is the data-backed minimum standard, and the go-around is always the correct response to being outside those parameters.
Every preflight walkaround matters. Nose gear wear - shimmy, strut pressure, torque link play - is detectable before flight, not just at annual inspection.
Safety investigation transparency is a systemic asset. Findings that stay private don’t prevent accidents elsewhere.