Another day, another bizarre, disturbing incident in our skies. This sort of thing has become so routine lately that it might be tempting to ignore it, but nothing was routine in the view of the passengers on United Airlines flight 1001 yesterday while they were taking off from the Los Angeles International Airport heading to Denver. The Boeing 757-200 was just lifting off when a loud "clunking" sound was heard. It turns out that one of the wheels on the plane's main landing gear had simply fallen off and was plummeting back to the ground. Nobody was injured and the plane still managed to land safely in Denver, but the incident was disturbingly similar to the one in March when another United flight lost a tire while taking off from San Francisco. That tire destroyed a car in the airport parking lot, but there thankfully no injuries during that event either. (Associated Press)

A United Airlines Boeing jet lost a main landing gear wheel Monday while taking off from Los Angeles and later landed safely in Denver, the airline said.

There were no reported injuries on the ground or on board Flight 1001, United said in a statement.

“The wheel has been recovered in Los Angeles, and we are investigating what caused this event,” the statement said.

While still not causing a significant safety issue, this incident was a bit more disturbing than the previous one. The 757 is a streamlined model that only has two wheels on the front landing gear and four on each of the rear landing gear. The much larger 777 has at least half a dozen wheels on each. Still, this flight was able to complete the trip to Denver and land without incident. The dislodged wheel was recovered in Los Angeles and will be inspected as part of the ongoing investigation.

It's great news that everyone landed safely and there were no injuries. The plane was carrying 174 passengers and 7 crew members. But this is clearly going to be one more lump of coal on the fire in terms of the ongoing investigation into Boeing's production, maintenance, and safety protocols. When manufacturing and performing maintenance on any sort of vehicle capable of rolling along, you would imagine that literally keeping the wheels attached would be among the most fundamental requirements on your to-do list. How does one of them just fall off and plunge back toward the ground when the plane is barely in the air?

All of these inspections, reinspections, and delays appear to be impacting Boeing's delivery schedule noticeably. It's being reported that Boeing sold just three passenger jets in June, along with roughly a dozen freighter jets to material transport customers. Two of the 737-MAX jets were sold to unnamed customers and the other was sold to Alaska Airlines to replace the plane that had the door plug blow out of it earlier this year. That represents a 70% decrease from the company's sales during the same period last year.

In another sign of possible trouble on the horizon, the FAA just ordered reinspections of 2,600 737 aircraft. They discovered an issue with some of the planes' oxygen generators where they were able to shift out of position during a flight, leading to a potential inability to deliver oxygen to passengers during a depressurization event. No such failure has been reported during a flight at this point, but it's a big enough safety concern to ground some of the fleet until it is corrected. Boeing continues to struggle as these inspections continue, but the flying public should be grateful that these issues are being addressed now and not after we lose another plane.