The crew donned night vision devices (NVD) at 2030, enabling them to see the horizon, and the mission continued without incident. However, the pilot elected not to land on the parent ship due to limited waveoff capability while the ship was undergoing replenishment at sea (RAS) with another ship alongside. The pilot decided to refuel at a DDG 51-class ship, even though he had not landed on this type of ship for a year. The copilot and aviation warfare systems operator (AW) had never made an approach to a DDG 51-class ship.
At 2045, upon learning the destination ship was unable to provide an NVD-capable platform, the pilot directed the crew to remove their NVDs and transition to white lighting. Given the go-ahead for landing, the Seahawk, with the copilot at the controls, made two passes at 200 feet as the ship turned toward the base recovery course.
The pilot then took the controls and turned toward final approach, 1.3 miles from the ship, a distance closer than is required by Naval Air Training and Operating Procedures Standardization (NATOPS) instrument approach procedures. The copilot did not challenge the pilot for the abbreviated pattern. The AW was preoccupied with post-landing duties and did not monitor navigation parameters.
After overshooting the final approach course by 20 degrees, the pilot rolled wings level at .8 miles, 200 feet above the water with 60 knots ground speed. Upon intercepting the red/amber interface on the stabilized glide slope indicator (SGSI) at .5 miles, the pilot depressed the collective trim altitude hold switch. He established a three to five degree nose-up attitude and reduced power to commence a decelerating descent to maintain visual glide path. Due to excessive closure rate, the pilot lowered collective more than normal to maintain the descent profile. The pilot observed a 100 to 150 feet per minute (FPM) rate of descent on the vertical speed indicator. He saw red (below glide path) on the SGSI but was not concerned, because he knew that on the alternate approach profile he would see red until reaching one-quarter mile and still be on profile.
He released the collective trim switch to engage the automatic flight control system (AFCS) radar altimeter hold. The descent rate averaged 800 FPM inside .5 miles while on final approach, exceeding the recommended rate of 500 FPM, but the pilot did not immediately sense the excessive rate of closure and rate of descent.
As the Seahawk decelerated through 50 knots, the AFCS automatically changed from airspeed hold to attitude hold. At 50 knots, airspeed dissipated due to increased nose attitude, decreased power and increased parasitic drag caused by stabilator programming to the near-full-down position.
Simultaneously, the rate of descent increased as the helo slowed due to an increase in required power that was not matched by a corresponding increase of collective power by the pilot. (The altitude hold function of the AFCS will overshoot selected altitudes due to limitations on its control authority, especially with a low power setting and high rates of descent.)
The copilot made altitude calls at 100, 80 and 60 feet followed by three rapid calls for power. Both pilots remember hearing radar altimeter warning system tones at selected altitudes of 100 and 60 feet. The rate of descent continued unabated until just prior to the aircraft's impact with the water. The crew did not see any engine, low rotor, master caution or other warning lights which would have indicated the pilot attempted to pull more power than the engines were capable of producing. But the pilot did pull sufficient power to decrease the rate of descent just prior to impact. This effort served to avoid injury to the crew but was not enough to avoid crashing .3 miles aft of the ship.
The aircraft immediately rolled right and went inverted. Prior to the SH-60B sinking, the aircrew egressed without significant problems and were rescued by the ship's crew within 22 minutes.
Grampaw Pettibone says:
There's a sayin' from an old movie, "What we have here is a failure to communicate." That phrase fits this sortie, along with "violation of NATOPS." The pilot didn't stick with the approach parameters outlined in NATOPS. Speak of gettin' off to a bad start!
The pilot was a bit slow to detect the excess rate of descent--a no-no, especially in the dark. But even so, had the crew operated like a team, helpin' each other out by better monitoring situational awareness and talkin' to each other, there coulda been a more positive outcome of the flight. Did the ugly head of overconfidence rear itself here?
The main problem: crew coordination took a holiday during this night approach.
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|Title Annotation:||GRAMPAW PETTIBONE; pulling more power than engines were capable of producing crashes plane|
|Publication:||Naval Aviation News|
|Date:||Nov 1, 2004|
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