On 26 January, two Alaska Airlines 737s suffered tail strikes on departure within just a few minutes of each other. According to reporting by The Seattle Times, that raised alarms for Bret Peyton, Alaska’s on-duty director of operations, who ordered all Alaska flights not yet airborne to remain on the ground until the cause of the incidents was known.
Off by thousands of pounds
The airline quickly learned both strikes were caused by faulty take off performance data, undercounting the weight of the aircraft by as much as 20,000 pounds, leading to the calculations calling for too little thrust to be used for take off and the pilots rotating too early for the actual weight of the plane.
The faulty performance data was generated due to a bug in the take off performance software used by Alaska Airlines. The firm, DynamicSource, identified the bug and fixed it within a few hours. Alaska Airlines says just 30 flights were affected by the erroneous figures.
Alaska flight 801
Alaska Airlines flight 801 was the first flight to suffer a tail strike on the morning of the 26th. Departing Seattle for Kailua-Kona at 16:48 UTC (08:48 local time), the aircraft climbed to the west before looping back to Seattle, landing 37 minutes after take off.
The 737-9 MAX N941AK was inspected and put back into service later that day arriving in Hawaii with a delay of just under four hours.
Alaska flight 887
Just five minutes after the departure of flight 801, Alaska Airlines flight 887 also struck the runway as it climbed away from Seattle. The 737-900ER N468AS was back on the ground again 20 minutes after take off.
Passengers from flight 887 were moved to Boeing 737-9 MAX N971AK, which departed Seattle with a three hour delay. The incident aircraft was inspected and put back into service the following day.
Hit the skids
The 737-900ER and 737-9 MAX are both 138 ft 2 in (42.1 m) long, the longest 737s currently in service. The Alaska Airlines 737s are equipped with a tail strike protectors, which are hydraulically actuated extensions. These tail skids on the longest 737s can prevent the main fuselage from being damaged in the event of a tail strike.
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