A mission over the Pacific Ocean took a critical turn Friday when a U.S. Air Force F-35 Lightning II fighter jet and a KC-135R Stratotanker tanker declared an emergency situation in the skies off the coast of San Jose, California.

The incident, which occurred at an altitude of approximately 37,000 feet (about 11,3 km), attracted the attention of aviation monitors when both aircraft simultaneously transmitted code 7700, the international transponder signal indicating a general emergency on board.

According to flight tracking data, a KC-135R tanker departed March Air Reserve Base in Riverside earlier that day. While conducting a mission over the Pacific Ocean, tracking data showed the tanker and the F-35 fighter jet flying at the same altitude and speed, suggesting an aerial refueling was either in progress or had recently completed. Approximately four hours and 30 minutes after takeoff, the KC-135R returned safely to March Air Reserve Base.

Although the F-35's final destination remained hidden from public tracking systems (a common practice for stealth fighters), the incident itself has raised questions. There has been no official confirmation from the military regarding the nature of the emergency. The simultaneous issuance of a distress signal suggests either an "in-flight incident" (such as a collision or close encounter) or a general technical malfunction that arose during the sensitive process of aerial refueling.

Earlier this week, on May 5, another incident involving a U.S. Air Force KC-135R tanker occurred in airspace over the Persian Gulf, where the aircraft also transmitted a 7700 emergency code. The tanker reportedly originated from Al Dhafra Air Base in the United Arab Emirates.

This incident marks the second consecutive incident involving American military aircraft in a short period of time. The US Air Force has so far declined to officially comment on the cause of both accidents.