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Featured Map for 11 March 2024:
United 35 San Francisco to Osaka ... via Los Angeles

 

(Here is a slightly better version of the map.)

The wheel in the sky ... is falling. (Er, apologies to Journey.)

Last Thursday, a United Airlines Boeing 777-222ER (N226UA) was operating UA 35 from San Francisco to Osaka when shortly after takeoff from runway 28R the inboard aft wheel of the left main gear separated and fell into a parking lot, damaging three cars and injuring one individual. As the aircraft climbed to FL320, the crew were informed by air traffic control of the loss of the wheel. After proceeding approximately 170 nautical miles along the planned flight path, the crew decided to return to SFO, then subsequently divered to Los Angeles. where the flight landed safely on runway 25L after 114 minutes aloft. After a brief inspection revealed no damage beyond the missing wheel the aircraft was towed to a gate.

United subsequently ferried another 777-222ER (N782UA, the first 777-200ER in revenue service) to LAX from SFO, where it had arrived from Munich.

My brother was curious as to why the flight diverted to LAX rather than returning to SFO, or possibly to nearby Oakland or San José.

Runway length would have been important given unknown landing-gear damage. The length of the longest runways at the three main Bay Area airports are:

That slightly favors SFO. In addition, absent an emergency, one would prefer to divert to an airport which has facilities to support the aircraft, ideally one served by the airline. Other than occasional sports charters, United only serves SJC with single-aisle aircraft, and doesn't serve OAK at all.

However, SFO's second-longest runway, 28L, which is 11,381 feet long, is currently closed for construction. With typical winds, 28L and 28R are used for arrivals with heavy departures usualy interleaved with arrivals on 28R. Most departures use 1R (8,650 feet) or 1L (7,650 feet). A landing gear issue runs the risk of fouling the runway if the aircraft cannot taxi off the runway, and had that happened on SFO's then the airport would have been crippled, with some of the heaviest long-range departures having to wait or plan a technical stop for fuel along the way (which can create crew legality issues atop other issues).

In addition to runway considerations, the flight needed to dump fuel to avoid an overweight landing, which was especially important given concerns about the landing gear. At least some of the added flying time required to divert to LAX would have been needed anyway to accommodate a fuel dump.

The longest runway at LAX (25L) is 12,925 feet long without risk of effectively closing the airport. United also has regular international widebody operations at the airport along with maintenance facilities.

Today's Featured Map shows the initial part of the planned flight (blue) along with the actual flight path (red). The potential landing airports are also marked and labeled with the length of their longest runway.

References and additional information:

 

 

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