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RC-135S 61-2664

Accident Case Study

The pilot clearly flew below glide path during the approach and then again once spotting the approach lights. The Air Force places the blame squarely on him. But that misses a bigger question: why did the pilot tend to "duck under" knowing the terrain just prior to the runway was so unforgiving? Or at all?


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Photo: 61-2664 at Shemya, Paul Jeanes

Click photo for a larger image

At the time, an AF team went around to several bases to say this pilot had a long history of doing the duck under, but the redacted report doesn't say that. It could be that this pilot just got suckered in by the visibility and wasn't trying to duck under the glide path. But he seemed to tolerate the "below glide path" calls without an aggressive move to correct. I've flown with several RC-135 pilots over the years who say the squadron did not allow the "duck under" before and after this crash but that now and then a pilot or two would start doing them again. Leadership is key. If those at top say don't duck under and take action against those who do, the practice will stop.

Accident Report

  • Date: 15 March 1981
  • Time: 2136 BST
  • Type: RC-135S
  • Operator: 6th Strategic Wing, Strategic Air Command
  • Registration: 61-2664
  • Fatalities: 6 of 24 crew, 0 of 0 passengers
  • Aircraft fate: Destroyed
  • Phase: Approach
  • Airport (departure): Eielson AFB, AK (PAEI)
  • Airport (arrival): Shemya AFB, AK (PASY)

Narrative

The aircraft did not have a Flight Data Recorder or a Cockpit Voice Recorder, but there were tapes of the Ground Control Approach (GCA) controller during the Precision Approach Radar (PAR) approach. The copy of the report I got through the Freedom of Information Act is heavily redacted. There are no redactions shown here because the pages I am quoting were unedited. But there were many pages missing.

[USAF Mishap Report, Factual Summary]

  • The mission was an RC-135S deployment to a forward operating location with air refueling, two navigation legs, and three orbits enroute.
  • The aircraft departed Eielson AFB, AK at 1451 AST (1351 BST) for a scheduled 7 hours and 8 minutes flight. After completion of the last orbit, the aircraft flew to WEBBI (IAF for HI TACAN RWY 10, Shemya AFB) and held for weather for 14 minutes from 2106 BST until 2120 BST. The aircraft proceeded, under radar vectors, from WEBBI to a precision radar final approach for Runway 10. After being advised of decision height by the radar final controller, and reporting "...we've got the lights," the right main landing gear contacted three approach light structures. Ground impact by both main landing gear and engines 3 and 4 rendered the aircraft incapable of controlled flight. Break up and fire started at impact, and the aircraft departed the right side of the runway in two sections. Six of twenty-four crewmembers were fatalities, and the aircraft was destroyed.

[USAF Mishap Report, Aircraft Flight Mishap Report]

  • Operator at the controls: Left Seat
  • Meteorological Conditions: Partially OBSC 1500' OVCST/5/16mi/winds; 130° 28K, Altmtr: 29.48, RVR 2400 ft
  • IMC
  • Distance of touchdown from runway: -200'
  • Length of runway: 9,992' (no overrun)
  • Precision Radar Approach flown at night in blowing snow to Rwy 10, Shemya AFB, AK. ALSF-1 approach lighting, 2,500 feet in length, with VASI. After passing decision height, struck three approach light structures and impacted ground prior to runway. Aircraft broke up and burned.

[USAF Mishap Report, Individual Flight Records, Pilot] Total Pilot Time 1694.1

[USAF Mishap Report, Individual Flight Records, copilot] Total Pilot Time 387.1

[USAF Mishap Report, Tape Transcript, Shemya GCA Final]

  • RFC: PAR Final Controller
  • 66: Exult 66 (Mishap Aircraft)
  • TWR: Tower
  • RFC: Exult six six, Shemya final controller how do you hear me?
  • 66: I read you loud and clear.
  • RFC: Exult six six you're loud and clear, also fly heading of one one zero.
  • 66: Roger one one zero.
  • RFC: On course and on final do not acknowledge further transmissions, eight miles from touchdown; turn left heading one zero five.
  • 66: Heading one zero five; drifting left of course; now turn right heading one zero seven.
  • RFC: Turn right heading one one zero; seven miles from touchdown.
  • RFC: Wind one two zero at two zero; approaching glide path; wheels should be down.
  • 66: Roger sir, we're gears down.
  • RFC: Roger.
  • RFC: Turn right heading one one two; begin descent; six miles from touchdown.
  • RFC: Wind one three zero at three zero; cleared to land.
  • RFC: Slightly below glide path; turn right heading one one five.
  • RFC: Left of course heading one one five.
  • RFC: Going well below glide path
  • RFC: Turn left heading one one three.
  • RFC: Five miles from touchdown.
  • RFC: Turn left heading one one zero.
  • RFC: Holding well below glide path; on course, heading one one zero.
  • RFC: Turn right heading one one two.
  • RFC: Holding slightly below glide path; slightly left of course; turn right heading one one five; four miles from touchdown.
  • RFC: Slightly below glide path; heading one one five, slightly left of course.
  • RFC: Wind one two zero at three zero.
  • RFC: Heading one one five; on glide path
  • RFC: Turn left heading one one two.
  • RFC: Turn left heading one one zero; now slightly right of course; three miles from touchdown; on glide path
  • RFC: Turn left heading one zero eight.
  • RFC: On glide path; heading one zero eight, right of course.
  • RFC: Turn left heading one zero six.
  • RFC: Going slightly above glide path; heading one zero six.
  • RFC: Turn left heading one zero four; two miles from touchdown; slightly above glide path
  • RFC: Heading one zero four, turn right heading one zero six.
  • RFC: On course, heading one zero six; drifting left of course, turn right heading one zero eight.
  • RFC: Turn right heading one one zero.
  • RFC: On glide path . . . left of course heading one one zero.
  • RFC: Going slightly below glide path; one mile from touchdown.
  • RFC: At decision height.
  • 66: Sir, we've got the lights.
  • RFC: Roger.
  • RFC: Slightly below glide path, slightly left of course.
  • RFC: Well below glide path.
  • RFC: On course; over landing threshold.
  • RFC: Tower.
  • TWR: He crashed close to the end of runway one five, I mean one zero.

Analysis

I read the full report back in 1984 and remember the conclusion that the pilot was prone to flying the PAR at a given descent rate, hence his tendency to fly below glide path when in a strong headwind. But that doesn't make sense given he had flown into Shemya many times before and those kinds of winds were not uncommon. Then, a year or so after the report was released, there was an Air Force wide message saying training records from one base should be forwarded to the next base. I was flying a version of the same aircraft that had about the same approach weight and speeds and we were given several briefings about the crash and special emphasis on the PAR. We were told that this particular pilot had a tendency to fly below glide path, but that was never documented in his check rides and training records from his previous assignments had never been forwarded. There is much to speculate about here because either the report didn't go into the human factors or that part of the report was redacted. I'm not sure. So the analysis that follows is mine, not the report's.

PAR Record

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Photo: Final Approach Diagram, Mishap Report, p. R-1

Click photo for a larger image

The drawing of the scope shows what the GCA (Ground Control Approach) controller would have seen. The top portion shows radar paint of the aircraft against an ideal 3° glide path, the bottom portion shows azimuth. The pilot's glide path control tended to be below glide path, though he did correct and slightly over-correct at one point. The "sir, we've got the lights" call was made after a slightly below glide path call but on the scope while well below. They were well below glide path when crossing the landing threshold.

There are several human factors issues involved that will not be apparent to someone who has never flown this type of Boeing 707, who has not flown into Shemya, has not flown this kind of mission where the airplane is filled with fellow crewmembers who want to get on the ground to get their week started.

  • Landing at Shemya required a lot of extra fuel, since the nearest alternate was hours away, and even further away for the RC-135S which was a "secret" bird that could not land at bases where it could be easily seen by the public. The airplane's normal approach speed was fast, even faster at Shemya.
  • The airplane was just barely up to the task of stopping on that amount of runway with any contamination. The brakes were prone to overheating and when that happened the tires were prone to exploding.
  • The C-135 community, and much of the "heavy community" in the Air Force at the time did not place a high priority on landing in the touchdown zone. Some units actually encouraged pilots to not only aim for 500' down the runway but to touchdown there as well. Some pilots aimed for brick one with the intent of flaring to the 500' point.
  • The "brick one" idea is widely discredited, but the dirty little secret is that it actually works given enough practice and proficiency. If a squadron is filled with pilots who can do it well, there is a lot of pressure on the other pilots to follow. The problem with the practice, however, is that on a day where there are visual obscurations, shifting winds, or pilot fatigue, the practice can end up with a very early touchdown.
  • The practice of flying a fairly long and intense training mission prior to a PAR landing at Shemya was thought of as good training for a wartime mission. The aircraft did have a very important wartime role during the cold war and there may have been some validity to the practice. But, after the fact, the idea appears to be flawed.
  • A pilot who routinely aims for "brick one" on a clear day will be prone to do so on a poor visibility day. The problem is that the pilot's depth perception is affected and aiming for the lights is not a good idea given the lights are positioned before the runway.
  • In the GCA transcripts you do not see a phrase used quite a bit in training and part of the GCA controller's lexicon: "Too low for safe approach, go around." I think this call would have been appropriate when the pilots called "we have the lights" but would have been unusual because the controller had probably seen this kind of glide path control before and the pilots always made it work before. It isn't the controller's fault, it is the system that tolerates it.
  • I believe a part of the report that was redacted is of the terrain just prior to the runway. I flew into Shemya several times and remember a steep upslope to the runway. The impact short of the runway was like flying into a bit of a cliff. There were more than a few Air Force runways back them with tire prints on the first part of the runway overrun, the result of an airplane touching down nearly 1,000 feet short of the runway at 1,700 feet short of the touchdown zone. (There were 18 wheels prints in the overrun at Andrews AFB for a number of years which could only have been made by one kind of airplane.)

Cause

I do not agree with the board's findings. Their causal findings say what happened, not why. If I were to write the findings, I would say:

  1. The Air Force failed to emphasize the need to land in the touchdown zone to training and standardization programs.
  2. The Strategic Air Command failed to consider the risks of flying long training missions prior to landings in poor weather at a very demanding location.
  3. The 6th Strategic Wing failed to institute stronger approach protocols for the PAR into Shemya, requiring directed go arounds when well below glide path

[USAF Mishap Report, Findings]

  1. The pilot did not understand the effect of headwind on glide path vertical velocity.
  2. The pilot failed to stabilize the aircraft on the precision radar glide path and shortly prior to decision height allowed the rate of descent to become excessive.
  3. At decision height the pilot's attention became channelized on the approach lights and crosswind control, allowing the excessive rate of descent to continue unchecked. (CAUSE)
  4. The copilot failed to effectively monitor aircraft performance and position. (CAUSE)
  5. The aircraft descended to a position from which the pilots were unable to correctly interpret approach and runway lighting through darkness and snow. (CAUSE)
  6. The aircraft impacted a ground upslope short of the runway sustaining damage which rendered it incapable of controlled flight.
  7. An aft body fuel tank explosion on the runway caused eventual empennage separation as the main fuselage veered right over an embankment parallel to the runway.
  8. Eight aircrew members were thrown from the broken fuselage, six were fatally injured, and the main fuselage section was destroyed by fire.

References

USAF Mishap Report, RC-135S SN 61-2664, Shemya AFB, AK, 15 Mar 1981, Redacted version obtained through Freedom of Information Act filed 7 Dec 2018.

Revision: 20190101
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