I’m adding a note here for all the peakbaggers. Oatman Mountain is a massive thing, 6 miles long by about 4 miles wide. It consists of 3 separate peaks, as follows:

Peak 1303 at the northwest end.

Peak 1722 in the middle.

Peak 1741 at the southeast end.

Most peakbaggers who have climbed there only know Peak 1741. It has the highest prominence (1,091 feet) and is therefore the biggest draw. There is a locked gate at its base. You can walk the road to the top where you will find several buildings and quite a few microwave towers which are still in use. It was on Peak 1722, the middle one, that Bob worked for 7 years. A road leads up to that site, but there is a locked gate at its base. The facility at Peak 3667 was referred to as the Sand Tanks Site by the military, which makes sense as it lies within the range known as the Sand Tank Mountains (just barely). We continue now with Bob’s words.

Here, I interject a question – what kind of negotiation took place between the Tohono O’odham nation and the military to allow such a facility to be built on their land? The TO have always been very protective of their land and don’t take kindly to outsiders doing anything there, and certainly not the US government. Did the Feds pay them for the privilege of constructing and operating the site? Under what terms? For how long a term?

In any case, in 1961 Pan American Airways built and operated the site on Peak 3667. Pan Am got the contract to operate the facility in 1960 and lost the contract in 1965 to Bell Aerospace, and it was around 1965 that the facility was closed down. Bob personally visited the site in the early 1970s for the purpose of seeing what could be done to resurrect the site, but no further action was taken to that effect.

On the TO reservation, the village of Kaka sits along the El Paso Natural Gas Pipeline Road. If you travel 3 miles west from Kaka on that road, you find yourself in the Kaka Valley. A lesser road then heads northwest for 7 miles toward the abandoned site of Moivayi, but before you reach that site, a road branches off of it at Point 2665. This road is important, as it is the one that heads up to Peak 3667. The military must have built the road because it is a real doozy. For its first mile, it rises gently up along a plateau.

At around 2,880 feet elevation, it makes a sharp turn to the east and starts to contour around the east side of the peak, climbing steadily. Even after sitting with no maintenance for decades, the road was still in excellent condition. It clearly had been relatively wide with deep hillside cuts and fills – there were even 2 culverts. This road had obviously been planned by engineers. At around 3,400 feet, the grade steepened noticeably. The road was blocked by a 2WD pickup, abandoned in years past, and it wasn’t possible to drive around it. This photo shows the steepness. Look between the saguaros – my truck is the white one lower down to the left.

Here’s a zoomed-in view.

I walked the remaining short distance up the road to the top of Peak 3667, but I wasn’t prepared for what I saw there that day – it was January 29th, 2006. Several concrete slabs adorned the summit. Several of them had markers embedded in them. There were 2 different types, shown here.

We now know that the PAA stands for Pan American Airways, and of course the 1961 tells the date it was installed. Bob has described what the site would have looked like back in the 60s when it was operational.

There were a number of concrete pads. Each one would have had a trailer parked on it. The trailers were about 8 feet wide and 25-30 feet long. A generator would have sat on one of the pads. There was a small building used for communications, perhaps 12 feet by 12 feet. Next to it stood a tower with 2 microwave antennas – one of them was aimed at Oatman Mountain, and the other was aimed at some site farther east, perhaps Mount Lemmon. There was precision tracking radar at the Yuma Proving Ground, Oatman Mountain, Peak 3667, Mount Lemmon and Fort Huachuca. The type of radar used were modified SCR584 tracking radar systems developed by MIT in WWII. SCR stood for Set, Complete, Radio.

Bob went on to tell me that, surprisingly, the crew that manned the installation didn’t live up there. Instead, they commuted there 5 days a week, and sometimes other days depending on the missions to support. But commuted from where?, I wondered. One possibility was from Gila Bend. Back in the 1960s, some of the roads on the Barry M. Goldwater Air Force Range were more heavily used and kept in better shape than they are now, and I can see a situation where such a commute could be done in an hour or an hour and a half, each way. That would still make for a long day in any case.

Now we come to the real reason the radar facility existed on top of Peak 3667. Are you ready for this? Drumroll ……… The site was built to track the progress of the Fairchild SD-5 Osprey. This was an early high-speed reconnaissance drone, to gather targeting information for the United States Army.

• Length: 36 ft 8 in (11.18 m)
• Wingspan: 24 ft 8 in (7.52 m)
• Height: 8 ft (2.4 m)
• Gross weight: 9,000 lb (4,082 kg)
• Powerplant: 1 × Pratt & Whitney J60 turbojet 3,000 lbf (13 kN) thrust

Performance

• Maximum speed: Mach 0.7
• Range: 1,000 mi (1,600 km, 870 nmi)
• Service ceiling: 35,000 ft (11,000 m)

Its rocket booster allowed for zero-length launch from a specially-designed trailer. Recovery following the mission was by parachute, with airbags used to cushion the landing; sensors including infrared scanners, side-looking airborne radar (SLAR) and optical mapping were available for use, and could be recovered following the mission, or transmitted during the mission via telemetry. Guidance during the mission was provided by an inertial navigation system and autopilot. The Army would launch the Osprey from Yuma and it would fly all the way to Fort Huachuca and then back to Yuma, if conditions allowed. The facility atop Peak 3667 would gather telemetry data during the flight.

Communications for every site was via the microwave radio communications system. Radar tracking data and telemetry data was also sent to different sites via the microwave system. Radar data was sent from a site that was tracking the data to other sites so that those sites’ radars cold be slaved to this data and allow those radars to acquire the aircraft. This data was very accurate and precise, allowing the radar operator to acquire the track easily. This same data could also be displayed on inked plotting boards (essentially a large-scale map of an area showing the real-time trace of the object the radar was tracking).

Bob’s 7 years of experience at Oatman Mountain helped him obtain a job working for Bendix Field Engineering, contracted to NASA to operate and maintain the MSFN (Manned Spaceflight Network) in support of the moon missions. He was trained and worked on several Apollo missions, including Apollo 11, at Greenbelt, Maryland, Ascension Island and Guaymas, Mexico.

Let me share with you some photos I took on my 2006 visit to the site atop Peak 3667. There wasn’t much left to see. Several concrete pads, and a wooden apparatus with what looked like a lightning rod on top.

One of the pads had some remnants of cables.

Sturdy wooden poles were still standing, A metal rod is on top of the right-hand pole, and conduit runs down the pole. It must have protected a cable at one time. A guy-wire holds up each side.

So there you have it, Friends. The mystery of Peak 3667 has been solved. The entire facility was built for one purpose, to help control and follow the movements of the SD-5 Osprey. This was an early high-speed reconnaissance drone, built to gather targeting information for the United States Army. Many thanks to Bob Morse for shining a light on all of this. I’m sure that the top of the mountain will sit undisturbed for years to come, if not forever.