Alaska Airlines (AS, Seattle Tacoma International) and Qantas Freight (Sydney Kingsford Smith) have returned their Israel Aerospace Industries-converted B737 freighters to service, although the American carrier is still restricting loads and the types of cargo accepted onboard the aircraft.

Both airlines, in addition to SpiceJet (SG, Delhi International), suspended the operation of their respective BDSF-converted freighters after the Israeli manufacturer discovered "an apparent irregularity" possibly leading to unsafe situations during emergency landings.

According to Flightradar24 ADS-B data, Alaska Airlines resumed the operation of all three B737-700(F)s on December 15, after previously grounding them on December 10.

On its website, the carrier said that certain operational restrictions were still in place as of December 18.

"General and Club 49 shipments continue to be embargoed until further notice to and within Alaska. Max weight is currently restricted to 800 lbs (363 kg) per piece for freighter flights. Main deck AVI/Live animal shipments are not available at this time," the airline said.

Express Freighters Australia (QE, Sydney Kingsford Smith), which operates four B737-300(F)s on behalf of Qantas Freight, reactivated all of them on December 16-17. They were previously grounded on December 10-11. The airline also operates one B737-400(F) on behalf of the Australian flag carrier but since the unit was not converted by IAI, it was not grounded.

Meanwhile, two out of three B737-700(F)s operated by SpiceJet continue to be grounded. The airline's sole B737-800(F), which was not converted by IAI, remains active.

The flaw relates to the so-called rigid barrier separating the cockpit and the freight deck. On December 12, 2019, the Civil Aviation Authority of Israel (CAAI) issued an emergency airworthiness directive related to all B737-300, -400, and -700 passenger-to-freighter jets converted by IAI, requiring operators to "reduce the cargo weights per each loading configuration and use of additional straps when necessary".

IAI said it delivered 47 converted B737s to customers but did not go into any specifics.