WASHINGTON: A glitchy software upgrade to the ALIS ground support system has grounded the Marine Corps F-35B squadron based in Yuma, Arizona, the F-35 Joint Program Office announced. Details are sparse, but a Marine Corps statement (reproduced in full below) said the unspecified “anomalies” only affected maintenance codes and only in the Yuma squadron, VMFA-211. The Marines have been the service most bullish on the F-35, pushing their variant, the F-35B jump jet, into service earlier than the Air Force or Navy.

Senate Armed Services chairman, former Navy fighter pilot, and F-35 skeptic John McCain swiftly issued a statement that he was “concerned” with the latest grounding but so far has held back from the ferocious criticism for which he’s famous.

Another Marine F-35B squadron, VMFA-121 in Iwakuni, Japan, is unaffected. The Air Force’s F-35As also seem to escaped the faulty upgrade, but they’re still wrestling with a different issue. Problems with the pilot’s air supply at high altitude temporarily grounded the F-35As at Luke Air Force Base, before they returned to flight under a restriction to low altitudes only. Air supply — drawn from the engine intakes the On-Board Oxygen Generation System (OBOGS) — has proven a problem for multiple types of aircraft, notably the Navy and Marine F-18 Hornet fighter and the Navy T-45 trainer.

ALIS, by contrast, is unique to the F-35. The Autonomic Logistic Information System is intended to ease maintenance, letting ground crews diagnose what parts are likely to fail and order replacements over a global network before a malfunction even occurs. The complex software has been a headache and a cause of delays in the past.

Here’s the text of the Marine Corps statement as provided to Breaking Defense:

Maj. Gen. Mark Wise, Commanding General of 3rd Marine Aircraft Wing, made the decision to temporarily suspend VMFA-211 flight operations pending fixes to a recent ALIS software upgrade within version 2.0.2 that has presented some anomalies.

ALIS is short for the Autonomic Logistic Information System Standard and it is the IT backbone of the F-35. ALIS is an off-board mission support system that manages operations, training, maintenance and the supply chain.

There is nothing wrong with the performance or safety of the aircraft itself, but it is imperative that we ensure the ground-based ALIS system is working properly before flight operations continue. The Joint Program Office and Lockheed Martin have dispatched system engineers to help resolve these issues associated with the ALIS software update.

The specific anomalies are related to maintenance codes not being reflected properly in the system and only affect VMFA-211 in Yuma, AZ and no other F-35 units. The F-35B is a highly capable aircraft with an excellent test and developmental safety record.

Corrected Friday 10:15 am: The original version of this article incorrectly stated the F-35 could not fly without a functioning ALIS syste.