Volf and others are right -- we're a month off ...
But to clear up some possible misunderstanding of what actually happened -- most helicopters landed on the ground (but still within the embassy compound) as the embassy roof couldn't handle the traffic or the weight of the '53's. Dirck Halstead's iconic photo
-- I interviewed Dirck once for an article and his perspective (as a civilian news photographer) was fascinating.Another view
The photo you usually see of the UH-1 on a rooftop is actually an Air America aircraft on the roof of the CIA compound -- Not actually/technically part of "Frequent Wind" just the spooks taking care of themselves...
The helo that gets most of the press, Lady Ace 09
from HMM-165 (Had a lot of friends who are White Knights) landed on the roof, but that was a special mission. God love the man (he was XO of The Basic School when I became a compass-holding Danger to Others), he is an entertaining speaker and a colorful leader, but not the "last" helo out of Saigon -- that dubious honor belongs to a CH-53:
"By the end of April 1975, no less than 13 North Vietnamese regiments ringed the South Vietnamese capital of Saigon and the diplomatic staff faced the obvious but hard truth that it was time to go.
"At 10 am, April 29, 1975, an order flashed to the fleet -- commence Operation Frequent Wind.
"The 23 Sea Stallions from HMHs 462 and 463 aboard USS Tripoli and USS Hancock were joined by 27 CH-46s from HMM-165, six UH-1s from HML-367 and eight AH-1Js from HMA 369. Additionally, 10 Air Force CH-53’s that had arrived onboard the aircraft carrier USS Midway from Clark Air Base in the Philippines, joined the package which was enroute to Saigon at 3pm.
"At the height of the operation, approximately 2 am on April 30, a CH-46 and a CH-53 were landing at the embassy every 10 minutes, guided by an AH-1J Sea Cobra.
"When “Swift 22,” a Marine Corps CH-53D, completed the last evacuation (the embassy security force) at 7:53 am, April 30, the largest helicopter evacuation on record had used 81 helicopters in a 19-hour period to lift 978 Americans and nearly 6,000 Vietnamese to safety aboard the ships of the 7th Fleet.
"Two hours later, the South Vietnamese government officially surrendered to the invaders."
-- Excerpted from an article I wrote for the '53D retirement. (My sources included the participating units' Unit Diaries/History, interviews with participants (including the photog referenced above) and the Official USMC history of Operation Frequent Wind.)
A sad day. But Frequent Wind was a good plan, hastily drawn up and expertly executed. Not the chaotic mess most would have you believe. The cool and capable professionalism of the Marines and Air Force (who executed it) is a bright spot in an otherwise ignominious chapter of diplomatic history. Of course, these same crews had practiced the whole thing only 2 weeks previously in a place called Phnom Penh ... (Operation Eagle Pull). And just two weeks later, on May 12, Marines of the III Marine Amphibious Force located at Utapao, Thailand and U.S. Air Force HH-53 and CH-53 aircraft located in Thailand, were on their way to Koh Tang Island to retake the SS Mayaguez (which they did). April and May, 1975 was a busy time...