Preliminary Report from the Waterbomber crash in Australia

 This was supposed to "drop" yesterday, but somehow I got the scheduler thingie off by a day.

   I clipped this off my 3rd party news I get in my email.

Credit: Gene Blevins/ZUMA Wire/Alamy

SINGAPORE—The pilots of a Coulson Aviation Boeing 737-300 firefighting tanker tried to pull the aircraft out from a retardant drop before accelerating the engines, resulting in the aircraft clipping a ridgeline and then crashing. 

Both pilots survived the Feb. 6 incident in Western Australia. 

In a preliminary report released by the Australian Transport Safety Bureau (ATSB), the aircraft—call signed Bomber 139—was carrying out its third sortie for the day to suppress bushfires at Fitzgerald River National Park. The 737 was guided by two airborne observers, known as bird-dog aircrafts, to the drop site. 

Bomber 139 commenced the first drop at 400 ft., only releasing three-quarters of the tank, with the engines running at 70% N1, which is defined as the rotational speed of the engine’s low-pressure compressor. 

Following the checklist for the second drop, the co-pilot said the drop speed would be performed at 118 kt. During the second drop, the aircraft descended through 400 ft. at about 110 kt. with engines at 30%, or at high idle.

The captain started to advance the throttle levers two seconds before the aircraft’s rate of descent peaked at about 1,800 ft./min. and started to pitch the nose up. The pitch preceded the acceleration of the engines, which the ATSB said in their report resulted “in a reversal of the rate of descent, but also a decay of the airspeed.” 

By that time, at a radio altitude of about 28 ft. with the flaps at 40 deg., an increasing aircraft nose-up pitch attitude resulted in the angle of attack exceeding 20 deg., which triggered the stick shaker. 

The aircraft struck the ridgeline at an elevation of 222 ft., with the engines at 85-89% N1. The ATSB said Bomber 139 “only attained a positive rate of climb just before impact with terrain.” The agency said the co-pilot reported that “their focus of attention was likely on the airspeed indicator and radio altimeter” at the time.

After making contact with the ridgeline, the aircraft cleared a line of foliage before colliding with the ground a second time, stopping about 577 ft. from its initial point of contact. 

Accident sequence distances and elevations. Credit: ATSB

Following the collision, the pilots issued an all-stations mayday call and exited the aircraft via the pilot’s left-side window.

The ATSB will continue investigations focusing on communication procedures between the 737 and the bird-dog. Its probe will also examine the pilot’s crew resource management as well as the standards and safety margins for the 737 retardant drop.

As part of immediate measures, Coulson Aviation issued an operations bulletin to increase its minimum drop height from 150 ft. to 200 ft. and increase the target drop airspeed from 133 k

                                                 I pulled this off "youtube"

                                                 This was off a News Report.