27,000 Feet in Ten Minutes: Delta 2311's Emergency Descent to Las Vegas

A Delta 737 dropped 27,000 feet in about ten minutes after a pressurization problem at cruise altitude triggered the oxygen masks — a descent rate that felt, in one passenger's word, "traumatic," even though everyone aboard walked off the aircraft in Las Vegas without serious injury.

A Normal Cruise, Then Masks Drop

Delta Flight 2311, carrying 174 passengers and 6 crew from Los Angeles to Salt Lake City, was cruising at roughly 35,000 to 36,000 feet — normal cruise altitude for a 737 on a route this length — when a pressurization fault developed. At that altitude, the air outside is far too thin to breathe; if the cabin loses pressurization, passenger oxygen masks are designed to drop automatically within seconds, which is what happened here.

The Descent

An emergency descent is one of the most aggressive maneuvers an airline crew flies in an otherwise normal operation — deliberately steep and fast, because the whole point is to get down to an altitude where the outside air itself is breathable (generally around 10,000 feet) before anyone's supplemental oxygen runs out. Air traffic control recordings captured the crew requesting an immediate descent to 9,000 feet while proceeding direct to Las Vegas rather than continuing toward Salt Lake City. The aircraft came down approximately 27,000 feet in about ten minutes — a rate steep enough that passengers described the experience as frightening, even though it was executed as a controlled, deliberate emergency procedure rather than an uncontrolled event.

A Normal Landing in Las Vegas

Despite the dramatic descent, the aircraft landed safely at Harry Reid International Airport, and passengers exited normally. Delta confirmed no serious injuries among those aboard, and issued an apology for the experience.

Back in Service Within Hours

The aircraft — delivered new in 2012, originally to Indonesian carrier Lion Air before Delta acquired it in 2023 — returned to service within hours of the incident. Aviation analysts noted that this kind of fast turnaround is typically more consistent with a minor pressurization valve or software-related fault than a more serious structural problem, though Delta and aviation authorities had not publicly disclosed the precise cause as of this writing.

Investigation Status

The exact cause of the pressurization fault has not been made public.

This reconstruction was researched from official investigation records where they exist, the original air traffic control recording, and contemporary reporting. The aircraft movement, timeline and written account were assembled independently by Flight Follower. Where an investigation is open or no probable cause has been published, the account says so rather than offering one.

Timeline

Sources and investigation material

• https://aviationa2z.com/index.php/2026/09/08/delta-737-drops-from-35000-feet-after-oxygen-masks-deploy-diverts-to-las-vegas/

Accident Facts

Sources

• Simple Flying, "'Pretty Traumatic': Delta Boeing 737 Drops To 9,000 Feet As Oxygen Masks Deploy"
• Fox News, "Delta Air Lines oxygen masks deploy amid scary pressurization issue on flight"
• Aviation A2Z, "Delta 737 Drops From 35,000 Feet After Oxygen Masks Deploy, Diverts to Las Vegas"