Brooks Air Force Base is a closed United States Air Force facility, located in San Antonio,TX.
It was closed on 30Sep2011.
It was one of 32 Air Service, US Army training camps established in 1918 after the United States entry into WWI, being established on 08Dec1917 as Kelly Field No. 5.
Flying at Brooks, however predates its military establishment, as the facility was known as Gosport Field prior to the first Army airplanes arriving on 05Dec 1917.

During the late 1950s, Brooks was transformed from a flying training center to a center for modern medical research and development and education center. The transition started in the summer of 1959 when the School of Aviation Medicine returned to Brooks from Randolph AFB.
An era in aviation history ended on 20Jun1960, when the last plane took off from Brooks. The aircraft was a C-131 'Samaritan', piloted by Col. L.B. Matthews, commander of Det. 1, 1st Aeromedical Transport Group.
https://en.wikipedia.org/wiki/Brooks_Air_Force_Base

I wondered what the link was with President J.F.Kennedy; then I read:
"President John F. Kennedy dedicated the School of Aerospace Medicine on 21Nov1963, the day before he was assassinated in Dallas. This was Kennedy's last official act as president!"

I would welcome more info on Kris Air; were they ever involved with CIA's covert air operations?
Steve Ozel wrote: ".. have you read Paul Howard's 'Mercy Angels of Angkor' article from a few years ago? This has details of these C-46's!"
Googling I found this may have been published in a 2006 issue of Air Enthusiast magazine. Details will be advsised!
This was written on Geoff Goodall's website (LINK), where he shares his "..photographs (taken) at Seletar Airport, Singapore and Denpasar Airport, Bali during July 1980".
Geoff includes the following info:"This advertisement in Asia Plane magazine was the genesis of Kris Air. As the American involvement in the SE Asian hostilities wound down in 1975, Continental Air Services Inc (CASI) C-46s N335CA, N336CA, N337CA were ferried to Seletar. They were acquired by the colourful American-backed Tri-9 Corp at Seletar and used on oil industry freight charters, adopting a new paint scheme with sea horse motif. When Tri-9 finished up in 1977, the newly-formed Kris Air acquired the three C-46s in a deal that included Tri-9's operating authorities and freight contracts."

So the B&W pic is probably Kris Air #1 and the colour(ful) C-46 is probably Kris Air #2!

Steve Darke forwarded me a 2005 article published in Air Enthusiast, titled 'Mercy Angels of Angkor', written by Paul Howard. Unfortunately the article scanned in Acrobat Reader .pdf format is weak in contrast, but the content is a fascinating read! And it does contain some detail of use of N335CA and N336CA.

While the caption does not plead for the thoroughness of the article, the content offers a huge amount of information concerning the 1973-1975 Phnom Penh Airlift and operaros involved.

"Mercy Angels of Angkor - the Phnom Penh Airlift, 1973 to 1975."

Paul Howard describes in a wonderfully detailed air Enthusiastic article how "..over 100 classic airliners flown by 30 or more carriers - both established and less orthodox - took a direct part in this mission of mercy."

"Following peace in Vietnam and the effect of a cease-fire in Laos, a number of veteran 'propliners' came to the fore in the Khmer Republic, owned, leased and operated by equality well-worn North American expatriate entrepeneurs who ran South East Asia Air Transport (SEAAT), International Air and Tri-9 Corp.
These enterprises had all been comfortably established in the region's leasing business since 1970 and had consolidated their respective fleets back at West Camp on the discreet Seletar airfield in Singapore."
They ".. took the opportunity to enlarge their fleets and buy up additional tired prop transports from 'boneyards' on Mainland USA and around the Australasian region ... used for sub-lease or resell at 'interesting' rates to the new operators springing up in the Khmer Republic."

"Oddly enough, despite the conditions, the influx of pilots content to continue working in SE Asia after the Vietnam conflict was initially higher than the number of aircraft available for them to fly! Many were ex-employees of Air America (AAM) and Continental Air Services Inc (CASI), both former large contract operators involved in SEA now winding down in the postwar environment."

'By 1973, the renamed Air Cambodge (March 1971, formerly Royal Air Cambodge - RAC) the government controled national carrier, was still suffering from ongoing neglect and .. corruption .. The government was forced to authorize Khmer Airlines ... the second airlines officially able to carry revenue passengers."
"..Robert 'Big Bob' Ferguson who, with Jack 'You've-Got-the-Wrong-Guy' Garfinkle of Tarzana,CA and Vice President Operations 'Stealth' (Cecil) Wroten operated South East Asia Air Transport (SEAAT), with an inventory of run-down Douglas DC-3s, DC-4s and the somewhat sophistocated and costly Consolidated Convair Liners.
"SEAAT lease deals to Air Cambodge kept it airborne and included examples of the above, plus an Aviation Traders Carvair, all US-registered and flown by pilots who held FAA lincences."
"China Airlines (CAL) of Taiwan was another source of equipment for Air Cambodge, leasing DC-4s...at various intervals. This was before SEAAT undercut them with its own DC-4s."
'A further source for Air Cambodge was the TRI-9 Corp, steered by another American expatriate 'Captain' Jim Ziegler, who supplied .. US-registered Convair Liners, filtered through Broker Alliance."
"Associated with these outfits was the incorrigible 'Stan the Man' - Stanley Booker of Stan Airplane Sales (of Fresno,CA), with Don Douglas, chief pilot of Stan's local venture, International Air." "Booker was well known in the Australasian region, having supplied Cessna 310s to the Indonesian Air Force. He bought several former RAAF Douglas C-47s cheaply, and used some to set up Sempati Airlines of Indonesia."

"The Republics' serviceable aircraft inventory, however, only totalled around 40 odd machines, far too few to satisfy the growing internal demand..." "The government reluctantly invited additional foreign (independent) air operators... with the proviso that a registered Khmer company was 'fronted' and a visible Khmeridenity maintained (flag and title, but not necessarily national markings)."
CASI... flown contracts around Indochina since the mid-1960s, had early expanded into the Khmer Republic. It created a subsidiary named Khmer Akas, using Convair Liners supplied by Jim Ziegler.."
'However, it was not long before CASI, a professionally-run operation ... refused to allow its subsidiary to accept bureaucracy, graft and corruption then existing in the Republic."
"Khmer Akas ceased operations following the tragic loss of DC-3 XW-PKY at Kampot. Trading off the subsidiary and some DC-3s to Khmer Hansa, a rejuvenated local operator, several aircraft found their way back to continue on the airlift in new liveries, while the Convairs were returned to TRI-9.
However CASI maintained a presence via untitled C-46 N337CA, which flew 'embassy' shuttles to and from Phnom Penh out of U-tapao,Thailand until spring 1975."

Following Khmer Akas' withdrawal, the Chinese connection ... filled the void, via the enigmatic captain Liao Chain Ming ('Jimmy' Liao)". He set about expanding the Cambodia Air Commercial (CAC) company (in which he had a funding stake), the operating arm (in the Republic) of Air Union, Laos with a fleet ... Laotian-registered DC-3s, plus a trio of C-46s and the rare Boeing SA-307 Stratoliners (two:XW-TFP and XW-TFR).
CAC rapidly became one of the busiest independent operators on Phnom Penh's Pochentong (Bao Cheng Tong) airfield."

"The majority of aircraft flying the airlift carried Laotian or US registrations." "The sizeable contingent of Chinese pilots held Taiwanese licences which enabled them to fly their own 'B..'-registered aircraft."
Because of bureaucracy involved, only around 14% of the aircraft capacity overall was actually registered in the Khmer Republic (XU-...)." "..included 2 Air Cambodge DC-4s, its longs-erving DC-6B, plus a DC-3 and Khmer A/L fleet of DC-3s. Largest of the remaining carriers was KHmer Hansa, ... flew seven DC-3s (XU-DAG, XU-EAH, XU-FAI, XU-GAJ, XU-HAK, XU-IAL, XU-LAN) and Soraya A/L with V. Viscount 768D XU-LAM and a pair of DC-3s, the latter registered in Laos."
"Meanwhile, Jim Ziegler's TRI-9 Corp... was supplying Convair Liners in the Republic." "..he acquired former Indonesian examples, re-registering them with US-marks, and, after performing limited maintenance at his Seletar base, put them on line."
"Ziegler also ... acquired ex/CASI C-46 N9760Z.. which was reported soon afterwards written off on the apron of Pochentong (It was also reported as ditched in the Gulf of Siam, off Kompong Som, the former Sihanoukville)."

"The Khmer Rouge overran the centre of Phnom Penh and April 16th. Most of the loyal airport staff that remained perished in the bloodbath that followed occupation."

"After the fall of the Khmer Republic, many of the aircraft that escaped were seized by creditors: some never flew - or moved - again, or else were scrapped where they stood.
By the end of that April, South Vietnam had also fallen, and later in the year, Laos, the final domino in the game, capitulated, bringing the end of Indochina."

The article (in 2 parts) identifies and deals with a large variety of 'propliners' such as the Big Dougs, the inevitable DC-3s, but also a Boeing SA-307 and an ATL.98 Carvair (nicknamed the 'Polish 747').
The size of the article makes it impossible to continue highlighting the main developments because there are too many.
While this .pdf document is not easy to read I would certainly recommend an attempt.

On CASI this website may be of additional interest:
"John Lear was a pilot for Continental Air Services, Inc. (CASI), a Subsidiary of Continental Air Lines which was in existence from 1965 to 1975.
It was formed in April 1965 by Continental Airlines at the suggestion of the United States Government. The objective was to provide a "less visible" air transport alternative to the CIA associated 'Air America' for the growing Laotian support."

The Howard Aircraft Corporation was a small USA aircraft manufacturer in the 1930s and 1940s. The factory was initially on the south side of Chicago Municipal Airport at 5301 W. 65th Street; during World War II a second plant was opened at DuPage Airport west of Chicago.
en.wikipedia.org/wiki/Howard_Aircraft_Corporation

The Howard DGA-8, DGA-9, DGA-11, and DGA-12 were a family of four-place, single-engine, high-wing light monoplanes built by the Howard Aircraft Corporation, Chicago, Illinois from 1936.
Variants:
DGA-8 - version with Wright R-760 engine (18 built, 1 impressed by USAAF as UC-70C)
DGA-9 - version with Jacobs L-5 engine (7 built, 2 impressed by USAAF as UC-70D)
DGA-11 - version with Pratt & Whitney Wasp Junior engine (4 built; several more converted from DGA-8, -9 etc.)
DGA-12 - version with Jacobs L-6 engine (2 built, both impressed by USAAF as UC-70A)
UC-70 - DGA-8/ -9/ -12 and -15 aircraft impressed into service with the USAAC as utility transports.

In 1939, the Howard Aircraft Corporation produced a new development of the basic design, the DGA-15.
Like its predecessors, the DGA-15 was a single-engined high-winged monoplane with a wooden wing and a steel-tube-truss fuselage, but it was distinguished by a deeper and wider fuselage, allowing five people to be seated in comfort.
It was available in several versions, differing in the engine fitted. The DGA-15P was powered by a Pratt & Whitney Wasp Junior radial engine, while the DGA-15J used a Jacobs L6MB and the DGA-15W a Wright R-760-E2 Whirlwind.
In an era when airlines were flying Douglas DC-3s, the Howards cruising at 160 to 170 mph could match their speed, range and comfort with the rear seat leg room exceeding airline standards with limousine-like capaciousness, and high wing loading allowing the Howards to ride through most turbulence comfortably.

Prior to the attack on Pearl Harbor in December 1941, about 80 DGA-8 through -15 aircraft had been built at the Howard Aircraft Corporation factory on the south side of Chicago Municipal Airport.
With America's entry into WWII, most of the civilian Howards were commandeered by the military.
The Army used them as officer transports and as air ambulances, with the designation UC-70.
The Navy, in particular, much liked the aircraft and contracted Howard Aircraft Corporation to build hundreds of DGA-15Ps to its own specifications. They were used variously under several designations as an officers' utility transport (GH-1, GH-3), aerial ambulance (GH-2), and for instrument training (NH-1).
en.wikipedia.org/wiki/Howard_DGA-15

Intially I found a San Antonio registered Howard DGA-15P as a candidate: N2737.
Joe Baugher has "Howard GH-3 Nightingale BuNo.45049 (MSN 1020), current as N2737"
www.joebaugher.com/navy_serials/thirdseries5.html
But on the FAA N-inquiry website I found it still reg'd to Keeling Mclin of San Antonio... So indeed 'current'.
Terry Fletcher wrote me in Dec.2015: "With regard to your Howard Nightingale query - I followed the lead on the sign in front of the aircraft , namely 'From USS Lexington'!
On looking up our locator in Aerial Visuals for 'USS Lexington' - it drilled down to N49478! Additional info provided: 'Howard DGA-15 / C-70 / GH / NH (Latest Model: GH). Last Military Serial: 44947 USN. C/N: 918.'

On 20Jul1997:
"The pilot/builder/designer was attempting to fly the airplane on its maiden test flight. During the takeoff roll, the pilot lifted the airplane's nose wheel off the runway two or three times, then the airplane lifted off the runway and climbed to an altitude approximately one half of the airplane's wingspan.
The airplane immediately returned to the runway in a porpoise like motion and lifted off a second time with a hard right roll. The airplane then impacted the runway in an inverted position.

Postaccident examination revealed the rudder exhibited crushed areas at the bottom and top. The top crushed area matched dimensionally to the four-belt driven wheel which turned the airplane's propeller.
A test pilot reported that during previous high speed taxi runs, conducted in August 1987, he had to apply 'stop-to-stop' elevator stick movements to maintain a steady pitch attitude.
A review of the video tape of the taxi tests revealed that the elevator was moving in what appeared to be 'stop-to-stop' movements.
The same elevator movements were observed in a video tape of the accident airplane during the attempted takeoff. The test pilot said he believed the airplane 'had some kind of pitch oscillation problem.'
CAUSE: inadequate design by the pilot/builder/designer. Related factors were: the porpoise that was encountered by the pilot during the takeoff, and the subsequent jammed rudder."
ASN quotes this from NTSB: http://www.ntsb.gov/ntsb/brief.asp?ev_id=20001208X08386