Robert W. Endlich
Part One: Operational Experience . . . When We Used NAS’s Data
INTRODUCTION
My work experience serves as a useful prelude to writing this post. I was a Weather Officer in the Air Force for 21 years, and soon after retiring from the Air Force, I became a Meteorologist working for the Army Atmospheric Sciences Laboratory, ASL, where my previous Air Force experience helped the mission at White Sands Missile Range, New Mexico.
One of my Air Force assignments was commander of the Weather Detachment at Davis-Monthan AFB, AZ, sometimes simply DM, on the southeast side of Tucson. I was assigned to Davis-Monthan from Sep 1976-Jul 1979, at the height of the Cold War. Though DM was a Tactical Air Command, TAC, Base, a major “tenant” organization there was a Strategic Air Command unit, the 390th Strategic Missile Wing, equipped with 18 Titan 2 Inter-Continental Ballistic Missiles, ICBMs, each in its own silo with a connected launch facility. The 18 Titan 2s in their silos were spread out, located 20-35 miles away from the base and Tucson proper. The Titan 2 was a large missile, fully loaded with powerful (and toxic) fuel and oxidizer, its propellants, sitting 24-hour Nuclear Alert. In the silo, the Titan 2 weighed 339,000 lbs. and was fitted with a single 9-megaton warhead.
Though the primary mission of my weather unit involved supporting training new A-7 and A-10 fighter pilots by the 388th TAC Fighter Wing, we also supported some 12 other operational squadrons. Among them were a drone-carrying C-130 organization, the 432d Tactical Drone Group, the Air Force’s “Boneyard,” called the Military Aircraft Storage and Disposition Center, MASDC, at the time, the 390th Strategic Missile Wing, and eight other flying units for which we provided weather support.
Within a short period of time of taking command of my weather unit, I became familiar with some of the maintenance required to keep the Titan 2s on 24-hour Nuclear Alert. Normally, well over 90% of the time, the missile was in its silo, fully fueled, on Nuclear Alert, and ready for launch within a few minutes, should the launch codes be sent from SAC Headquarters at Offutt AFB, Nebraska.
Sometimes maintenance of the Titan 2 required that either the fuel, Unsymmetrical Dimethyl Hydrazine, (UDMH) or the oxidizer, Nitrogen Tetroxide, (N2O4) needed to be offloaded from the missile to a propellant-handling tanker truck, so that the maintenance on the missile could proceed. When such maintenance needed to be done, there was a possibility that, during movement, the toxic propellants might be spilled on the ground where they would evaporate into the atmosphere or be discharged directly into the atmosphere–from a burst hose, broken hose coupling or other accident. To avoid exposing nearby people to life-threatening concentrations of these toxic gases during planned or accidental releases of Titan’s toxic chemicals, my weather unit prepared specialized weather forecasts, Toxic Corridor Advisories. Unlike weather support to aircraft operations, preparation of Toxic Corridor Advisories needed to characterize the ability of the lower atmosphere to diffuse toxic chemicals from the point of release. If toxic propellant leaked into the atmosphere, that propellant would diffuse as it moved downwind. The toxic corridor length was the distance downwind where the concentration would be diluted to less than the Short-Term Public Emergency Limit, the STPEL. Defining these critical concentrations, the STPELs for each chemical were within the purview of the National Academy of Sciences Committee on Toxicology.
This particular Titan 2 maintenance procedure had its own name: Propellant Transfer System operation, usually just PTS. Each PTS involved the movement of special propellant-handling equipment to the missile launch facility. These were tanker trailers for the propellant, pumps, hoses, and connectors needed to pump the propellants from the missile into holding and conditioning trailers. All needed to be in place before the maintenance could be performed.
There is a video of the PTS procedures for the Titan 2 at https://www.youtube.com/watch?v=wVRA8NRr4Gg, The MOST Dangerous Job in the Air Force…Feeding the Titan–Propellant Transfer Team.
Throughout the entire PTS, the pressure and temperature of the propellants would be monitored inside a command trailer. A PTS had these special safety considerations because both the fuel and the oxidizer were toxic.
INFORMATION REQUIRED FOR A TOXIC CORRIDOR ADVISORY
*****The weather unit prepared the Toxic Corridor Advisory upon request of the PTS crew at the specific missile site where PTS maintenance was being performed.
Prediction of an Operational Toxic Corridor involved knowing:
- Which Chemical was involved, UDMH or N2O4
- The Source Strength of the chemical, the rate at which the chemical was released into the atmosphere, related to the “wetted area” of a spilled chemical on the ground, or the rate at which propellant was leaking directly into the atmosphere.
- The downwind direction of the wind.
- The wind direction variability.
- The <16M-2M> temperature difference, frequently called the “Delta-T.” Each Titan 2 missile site had a “Delta T” pole with temperature sensors for on-site direct readout of this temperature difference. Also, on each Titan 2 site, there was an anemometer, from which we would get the downwind direction and the wind direction variability.
Figure 2. Aerial view of the Titan Missile Museum, launch site 571-7, near Sahuarita, AZ. Visitors can see facilities and equipment used during the days when the 390th Strategic Missile Wing of the US Air Force maintained one of its eighteen Titan 2 missiles on Nuclear Alert here, during the Cold War. The image is annotated with many of the facilities and support equipment used to maintain the missile on Nuclear Alert.
Weather Detachments supporting Titan 2 ICBMs had unit Standard Operating Procedures, SOPs, published procedures, where each of these elements would be written down, a checklist to be filled out, and the resulting calculations provided to the PTS crew. The toxic corridor advisory was a written description of the area downwind of the silo threatened with a toxic atmosphere if a leak of either UDMH or N2O4 occurred during the PTS. The Weather Unit’s SOPs were based upon and used tables published in Air Weather Service Pamphlet 105-57, “Calculation of Toxic Corridors.”
In 1980, AWSP 105-57 was declared obsolete with the publication of AWS Technical Report 80-3, “Calculating Toxic Corridors.” The first author of AWSTR 80-3 is now CASF’s Webmaster, Jon Kahler. AWSTR 80-3 is on-line here: https://apps.dtic.mil/sti/pdfs/ADA221955.pdf.
AWSP 105-57 had a series of tables of toxic corridor lengths for UDMH and N2O4, with each table having as the abscissa the(16M-2M) Delta-T (Deg F) and the ordinate, the chemical’s source strength. The number at the intersection was the distance from the point of a chemical release, downwind until it diffused down to the Short-Term Public Exposure Limit, the STPEL.
Figure 3. Sample UDMH toxic corridor length table used by the forecaster preparing the Toxic Corridor Advisory. The top line is the Abscissa, listing the Delta-T measured at the missile site, and ranging from -4F to +10F. The Ordinate lists a series of source strengths should a leak of UDMH, the Titan 2 fuel, occur. The stack of distances at the intersection represents three different toxic corridor lengths, depending on which PEL was used. In this example, the top line was the 10-minute Short Term Public Exposure Limit, the middle line, the 30-minute Short Term Public Exposure Limit, or the bottom line, the 60-minute Short Term Public Exposure Limit.
Figure 3 comes from AWSTR 80-3, https://apps.dtic.mil/sti/pdfs/ADA221955.pdf.
It is functionally the same as the toxic corridor tables that we used in AWSP 105-57, at Davis Monthan AFB, from 1976-1979.
When personnel visiting my weather unit from higher headquarters came on base, usually I escorted them to one of the Titan 2 missile sites where they could see first-hand an On-Alert Titan 2 and meet the 4-person Air Force Missile Crew. My weather Maintenance Section insured that the Delta-T and anemometer needed for toxic corridor preparations were calibrated and maintained to assure the quality of these measurements, while my weather forecasters prepared the Toxic Corridor Advisories for the PTS crew.
The 390th Strategic Missile Wing ensured that the missiles were ready to launch on a 24-hour basis. Normally each Titan 2 maintained its On-Alert status in the neighborhood of 91-95% of the time.
AN ASSIGNMENT IN COLD-WAR GERMANY, AND THE NEED FOR CHEMICAL WARFARE DEFENSE.
My follow-on assignment from Davis-Monthan AFB, was Staff Weather Officer to the U.S. Army’s VII Corps in Stuttgart, in Cold War Germany, for three years, 1979-1982. The Soviet forces opposing us were the Eighth Guards Tank Army and other formations of the Group of Soviet Forces, Germany, GSFG. These units opposing us were equipped with Conventional, Nuclear, Biological and Chemical Weapons.
In VII Corps, we were part of the NATO’s Central Army Group, CENTAG. Description of the military units whose mission was to fight in the event of war is called “The Order of Battle.” The order of battle for CENTAG is described here: https://en.wikipedia.org/wiki/Central_Army_Group_(1989)_order_of_battle
Our weather forecasters in VII Corps (and to our left, V Corps, headquartered in Frankfurt and our German colleagues in III GE Korps and II GE Korps) were prepared to provide the assigned military NBC (Nuclear, Biological, and Chemical) teams with specialized forecasts and meteorological data used in NBC defense. This included, but was not limited to ground surface temperatures, temperatures of and the atmospheric stability of the air just above the surface, surface winds and winds aloft, and cloud cover data, all used in Chemical Warfare Defense. My Weather Team was involved in forecasting the transport and diffusion of Soviet Chemical Weapons “just in case” the Cold War turned Hot.
The point is, in addition to forecasting for ground maneuver for the defense of our sector, we needed to know detailed weather at the surface which affected chemical and biological agents and surface stability, and the winds aloft from the surface to the stratosphere for radioactive fallout predictions.
A NEW ASSIGNMENT, AND A NEW REQUEST FOR TOXIC CORRIDOR SUPPORT.
I retired from the Air Force on 1 April 1984 and joined the Army Atmospheric Sciences Laboratory, ASL, at White Sands Missile Range, WSMR, as a civilian meteorologist on 9 April 1984. My work assignment was chief of the High Energy Laser Support Section with duty at the High Energy Laser Systems Test Facility, HELSTF.
People at ASL knew me, since I had experience in atmospheric effects on lasers and high energy lasers, from my assignment in the early 1970s, to Kirtland AFB, also in New Mexico, when I was Staff Meteorologist to the Air Force Weapons Laboratory, and its Laser Division.
This was during the Cold War; Ronald Reagan was President of the United States. President Reagan’s emphasis at the time was on developing a capability to defend the United States against nuclear attack from the Soviet Union. Strategic Defense was an important imperative to him, and of the Department of Defense, DOD. Here in the United States, this initiative was called the Strategic Defense Initiative or SDI, though critics called it “Star Wars.” This nickname stuck because of the popularity of the movie Star Wars, in the summer of 1977, where powerful ray guns in the film were shown to be colorful and effective offensive and defensive weapons of the future.
At the time of Reagan’s presidency in the 1980s, the SDI effort involved using extant and to-be-developed systems of DOD, prioritizing useful defensive research and development efforts. These efforts were to become the technical base and the platform used to develop Reagan’s proposed defense of the United States against nuclear attack, nominally from the Soviet Union.
One of these efforts involved moving a Navy technology demonstration laser, the Mid Infra-Red Advanced Chemical Laser, the MIRACL, from the TRW test range in the hills behind San Clemente, CA, to the newly-created National High Energy Laser Test Range, at HELSTF. This facility was developed in the middle of White Sands Missile Range, New Mexico.
Before I arrived, a suite of meteorological equipment had been installed by ASL at HELSTF to provide measurements for atmospheric effects on the High Energy Laser beam when the MIRACL became operational and was propagating the MIRACL’s 3.8um beam downrange.
The first day I reported for duty at HELSTF, the site’s Division Chief asked me to work with his Site Safety Officers to develop a methodology to aid in handling the toxic chemicals used in operating the MIRACL device. Site Safety’s Officers asked how I might be able to help when, weeks in the future, they’d conduct test operations moving toxic oxidizers from their storage tanks into the MIRACL device.
The first such tests would be cold flow of the gases, when chemical fuel flow without ignition in the MIRACL device, would occur. Soon thereafter, they’d ignite the fuel, Ethylene gas diluted with Helium, with the strongest oxidizer from the periodic table of the elements, raw Fluorine gas, F2, in the MIRACL device, to ignite the fuel, and, in the lasing cavity, create excited Deuterium Fluoride, which would be the source the 3.8um laser radiation.
After ignition with the F2, they used Nitrogen Trifluoride, NF3, to sustain the ignition of the fuel in the MIRACL device. Both F2 and NF3 were toxic, and Site Safety needed help in developing safety procedures when these toxic gases were moving from their storage tanks into the MIRACL device.
After a test run of MIRACL, the Deuterium Fluoride, also toxic, would be “scrubbed” chemically, then exhausted from the device.
I told Site Safety that I had experience providing weather support to the Titan 2 missile wing at Davis Monthan AFB in Tucson, and that I could provide Toxic Corridor Advisories based on the source strength of the possible spills or leaks of the F2 and NF3, and the critical concentrations of DF in the MIRACL exhaust.
I said, if Site Safety could tell me the critical chemical concentrations to which each toxic chemical needed to diffuse for their safety determinations, I could provide them with a Toxic Corridor Advisory during Test Operations, defining the distance during which the chemical would remain in toxic concentrations. Together we determined that the critical chemical concentration was the National Academy of Sciences Committee on Toxicology’s Short-Term Public Exposure Limit, the STPEL, for each chemical.
It was easy to obtain a copy of AWSP 105-57 from the Weather Detachment at Holloman AFB, the Air Force Base adjacent to WSMR, near Alamogordo, NM.
Working with my electronics technicians, who had been previously hired into the High Energy Laser Support Section, I was soon able to generate time series plots on a strip chart recorder of the <T16m-T2m> signals needed for toxic corridor calculations. We also brought Wind Direction and Wind Speed data into our Meteorological Room at HELSTF. That enabled me to have in, near real time, representative, on site, and redundant, appropriate meteorological measurements needed to provide Toxic Corridor Advisories to support MIRACL test operations.
On MIRACL test days we provided the Toxic Corridor Advisories to Site Safety, and they used them in their own procedures and checklists to avoid exposing HELSTF personnel to life-threatening concentrations of these toxic gases during planned or accidental releases of those toxic chemicals.
When the Cold Flow tests started in the summer of 1984, either one of my forecasters or I provided written toxic corridor advisories to the Site Safety Officers overseeing the test count, and we provided new advisories if the Delta T changed by a degree F during the test, or if the downwind direction changed significantly.
HELSTF’s Test Operations proceeded from the summer of 1984 and were in full operation for ten years, after which I was transferred to another assignment in 1994. Sometimes HELSTF’s operations were in the national news.
Figure 4. Left, an image of the Mid Infra-Red Advanced Chemical Laser, the MIRACL device, which was used to generate a powerful source of 3.8um laser radiation. Many tests were to a test cell 500 meters downrange from the device. In later dynamic tests, the laser beam was sent to the pointing, tracking and focusing telescope, to irradiate targets in flight, to see the effects of the laser illuminated on flying targets.
SIDEBAR
Static Tests:
In 1985 the MIRACL device beam was propagated to the 500-meter site at HELSTF, where a TITAN 2 missile body had been pressurized and put under tension to simulate an ICBM in the boost phase. When the beam hit the missile body, it exploded. An image of the test result was on National TV News the next several days, example below.
Figure 5. Image of the test where the MIRACL laser beam was propagated to the 500-meter site, where a Titan 1 missile body was pressurized with water and put under tension (you can see the tensioners in the image) The resultant explosion of the missile body was on TV for the next few days.
Dynamic Test:
In 1989 HELSTF conducted a test in which the MIRACL laser beam was propagated through the Sea Light Beam Director at a Vandal missile (at the 3:12 mark in this video) traveling over Mach 2 and shot it down in mid-flight. (pg. 202)
Image of the Vandal Missile during flight at WSMR at over Mach 2 speed, when the Vandal was being illuminated by the MIRACL beam shot through the SLBD. The laser beam has a wavelength of 3.8 um and is invisible to the naked eye or to cameras sensitive to visible radiation. In this image, the MIRACL beam has dwelled on the side of the missile, depositing a huge amount of energy, so much, that the Vandal is glowing red hot, in the visible. An instant later the Vandal exploded into smithereens. This image taken from https://www.youtube.com/watch?v=7drp8hp2Kto at 3:12.
END SIDEBAR.
To summarize, during the fifteen-year period 1976-1991, when I was involved in military operations at Davis-Monthan AFB, and Research and Development efforts at White Sands Missile Range, my colleagues and I used data provided by the National Academy of Sciences Committee on Toxicology as the baseline standard and authoritative source for the safety calculations we used, sometimes on a daily basis.
We had no reason to doubt the National Academy ever, during those years.