LOT Polish Airlines (LO, Warsaw Chopin) and Enter Air (E4, Warsaw Chopin) resumed B737-8 operations on March 24 and 25, 2021, respectively, after more than a two-year gap caused by the type's grounding, while Turkish Airlines (TK, Istanbul New) is planning to do so on April 12, 2021.

The Polish flag carrier operates five B737-8s, all of them dry-leased from ALC Blarney Aircraft, the ch-aviation fleets advanced module shows. The first post-grounding flight from Warsaw Chopin to Oslo Gardermoen was operated by SP-LVD (msn 64069). The remaining four aircraft remain in storage, two at Warsaw Chopin airport and two in Lublin. One of the two units stored at Warsaw airport has already been recertified by the Polish Civil Aviation Authority (Urząd Lotnictwa Cywilnego - ULC) and is expected to resume commercial operations soon.

LOT said that on top of all the changes mandated by EASA, it is also planning to have each of them undergo an additional C check. Thereafter, they will also conduct internal proving flights before their reinduction into service.

Fellow Polish B737 MAX operator, Enter Air, operated its first B737 MAX commercial flight on March 25 from Katowice to Tenerife Sur, using SP-EXA (msn 64295). The airline's second unit of the type has so far only been active on proving flights on domestic routes in Poland.

In turn, Turkish Airlines operates eleven B737-8s and a single B737-9. While the airline has yet to confirm the date of their formal re-entry into service, the German edition of the Hurriyet daily reported it was due to happen on April 12. Flightradar24 ADS-B data shows that while the airline started ground tests of the aircraft at Istanbul New, it has yet to operate any proving flights. On top of the twelve B737 MAX already delivered, Turkish Airlines has firm orders for a further fifty-four B737-8s and nine -9s.