On September 17th, a United Airlines Boeing 737-900 tipped backward,
experiencing a stationary tail strike- more properly known as
‘tail sitting’. Having arrived in Lewiston (Idaho) after a flight from LAX, the aircraft
was photographed in its unfortunate position, with the picture then being shared on Twitter.
The flight into Lewiston was a charter service to fly the University of Southern California’s
football team, the USC Trojans, to play against Washington State.
The aircraft involved was a United Airlines Boeing 737-900ER.
A photo posted on Twitter shows the aircraft tipped backwards onto its tail. Near the
middle-front area of the 737, airport crews can be seen surrounding it. In the foreground, a
baggage tractor can be seen parked, with a couple of ‘onlookers’ spotted even closer to the camera.
The 737 had landed in Lewiston at 17:13 local time, according to data from RadarBox.com,
and is registered as N78448. Delivered in March of 2012, this particular aircraft is
a nearly 10-year-old 737-900ER configured with two classes: 20 seats in business and 159 in economy.
Simple Flying had contacted United Airlines regarding the details of this incident.
Responding to our inquiry, the airline issued the following statement:
“United flight 2509 flying from Los Angeles, California to Lewiston, Idaho
landed without incident. Due to a shift in weight and balance during the offloading process,
the tail of the aircraft tipped backward. No injuries were reported among our customers,
crew or ground personnel. The return flight was on a different aircraft as originally planned.”
As confirmed by the airline, this incident was caused by an imbalance of weight,
which took place during disembarkation. If we assume that passengers disembarked only from
the front door of the 737, we can imagine that the aircraft would be increasingly ‘tail-heavy’ as
people stepped off the aircraft in a front-to-back offloading procedure. Many have commented that the
heavier-than-average football players would have made up most of the passengers on the aircraft.
With a loaded baggage cart positioned in front of the aircraft in the photo,
we can infer that even more of the aircraft’s front weight was removed. Indeed,
the offloading of baggage from the aircraft’s front cargo hold
would only serve to further exaggerate the imbalance between the front and rear of the jet.
Another factor would have been the absence of a tail stand, which is used to “prop up” or
reinforce the aircraft’s tail during the loading and unloading of cargo.
Those commenting on the Twitter post note that this important piece of equipment was
either forgotten or not provided by the airline and unavailable at the airport.
It should be said that not all aircraft require a tail stand. However, it’s been noted by some that
the Boeing 737-900, in particular, is rather tail heavy and has a higher risk of tipping.
As a result, it would be one aircraft type using a tail stand more often than other jets.
In the end, it’s a rather embarrassing and costly incident which fortunately didn’t result in any
injuries. Of course, the whole ordeal should make for a memorable season for the USC Trojans.
What do you think of this incident? Did you know about the 737-900’s
weight and balance characteristics? Let us know what you think by leaving a comment.