B737 Next Generation Undifferentiated
Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine; Flight Crew Instrument
Flight Crew Last 90 Days 188; Flight Crew Total 2335; Flight Crew Type 1744
Troubleshooting; Distraction; Situational Awareness
Aircraft Equipment Problem Critical; Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor
Flight Crew Landed in Emergency Condition; Flight Crew Returned To Departure Airport; Flight Crew Overcame Equipment Problem
Aircraft
ZZZ-ZZZ1; on time departure; push-back-initial climbout were uneventful. I was pilot flying; climbing through FL280 on our way to FL350 on the ZZZZZ 2; a loud audible bang occurred; simultaneously the aircraft shook and Engine Number 1 seized. Captain and myself immediately smelled fumes I would describe as acrid. We immediately performed memory items and Captain pulled out QRC (Quick Reference Checklist). There were very strong aircraft vibrations. We decided to run severe damage procedure because of the combination of vibration and fumes. We [requested priority handling] and decided to return to ZZZ. I turned the aircraft around and Captain talked to FA (Flight Attendant)'s and made a PA. On descent back into ZZZ; we transferred control and Captain flew while I coordinated with ATC; Dispatch; FAs and informed passengers. Captain flew an uneventful single engine visual to XXR. We stopped in between the 2 runways and had fire trucks look over the aircraft and brakes; after which they told us they didn't see anything. We coordinated with Ground and returned to our original gate. I entered an ELB (Electronic Logbook) entry at the gate and we verbally debriefed Maintenance. We informed [Chief Pilot] we would not fly another leg this day.
During climbout from ZZZ at around 28;000 the left engine failed with odor and a slight vibration. [Requested priority handling] and ran the Severe Engine Damaged checklist and returned to ZZZ for a safe landing.
B737 flight crew reported number one engine failure; odor and vibrations; which led to a return to the departure airport.