We’ve been following Karl Porisch, who graduated from Mankato State in 1968 and completed Marine Corps officer and helicopter flight training. The Marines assigned Karl to Okinawa, while his spouse and infant son stayed with her parents in Chicago. The Marines reassigned him to the 1st Marine Air Wing at Marble Mountain Airfield south of Danang, Vietnam in October 1970. He joined Marine Medium Helicopter Squadron 263 (MMH 263) there and began crewing CH-46, dual-rotor helicopters.

Karl explained the mission of Marine CH-46 units in Vietnam.

“The ’46’ was designed for two things; hauling (internal) cargo or troops or using the external hook to pick up a sling-load and transport supplies or troops to the field. The primary missions of the 46 squadrons were resupply, troop insert or extracts, and Mission 73, which was recon. Then there was day and night medevac.”

Karl described the area of Vietnam where MMH 263, radio call sign “Peachbush,” operated.

“We were in I Corps, which was the northernmost Corps. We seldom went past the Hai Van Pass just north of Danang toward Phu Bai or Hue. The TAOR (Tactical Area of Responsibility) stretched roughly from the Hai Van Pass to LZ (Landing Zone) Baldy, a fire support base for the 7th Marines that was 20 to 25 miles south, and then west to the border with Laos. The NVA (North Vietnamese Army) and Viet Cong were thick in the Que Son Mountains. LZ Baldy was maybe 6 miles from the ocean and on the edge of the Que Son Mountains. They had 105s, 155s, and 8 inch guns (long-range artillery) that would support Marine operations in that area.”

Karl’s unit had 20 CH-46 helicopters, but 5 or 6 were generally out-of-service for routine inspections. He described their aircraft and crews.

“The ’46’ was a tandem rotor helicopter with one rotor on the aft pylon and one up front. It had two, turbine engines and little, stub wings where the rear main mounts (landing gear) and fuel cells were located. They had an auxiliary power unit (APU), a little turbine engine in the very back. You’d start the APU first and that gave you power to start the main engines one at a time. It had a “clamshell.” (Rear ramp and door) The crew chief let down the bottom part so troops could get on or off.’

Their aircraft were armed and this added to the aircraft’s crew.

“They took out the helicopter’s windows so that if you were at a hot LZ and had troops with M-16s to return fire, you didn’t have to bust out a window. Right behind the co-pilot, who flew in the left seat, was a rectangular window they took out and built a .50 caliber machine gun mount. That pindle mount only traversed so far both ways. They also did that just aft of the front door (opposite side) where they put another .50 cal. So, the full crew was the pilot (Helicopter Aircraft Commander or HAC), co-pilot, crew chief, and two gunners.”

Karl explained the flight assignment process.

“We would get the flight schedule from the Danang Air Support Center (DASC). (Squadron Operations) assigned pilots and we would have all the missions: morning medevac; afternoon medevac; resupply; stand-by; and the schedule for the whole day. The Marine Corps always flew with two helicopters, called a section. The reason was that if one got shot down, the other was there for support. There were missions that were more dangerous than others. Mission 73, which was recon insert/extract, was nasty because you were often extracting a recon team under contact. Those were assigned on a rotational basis. Night medevac was the same way. They’d deliver the (flight roster) to the pilots’ hootches so by ten o’clock everybody knew what they’d be doing the next day.”

Karl outlined the typical flight mission sequence, beginning with the duty driver picking up pilots and co-pilots on runs between the officer hootches and the Ready Room in the Operations Quonset.

“The co-pilot had to be there early for pre-flight. The crew chief and gunners would already be aboard the aircraft. You started on top and went through the forward transmission area. You checked all the connections to the transmission. You checked the control surfaces on the rotor head and made sure that they were safety-wired. You’d go to the back and do the same. Then you’d do a walk-around (looking for oil or hydraulic fluid leaks). The section leader gave the brief. The Ready Room had a big map of our area. You’d sit through the mission brief, “Today we are going to resupply the 5th Marines …” and you got their location coordinates, radio frequencies, and all that.”

The co-pilot manned the radios. Karl (radio call sign “Peachbush 10) recreated a typical take-off sequence.

“As co-pilot the first thing you did was call Ground Control; “Marble Ground, this is Peachbush 10, we are 263 for taxi.” The tower came back with the barometric pressure; wind speed and direction; and any aircraft traffic in the area. He’d tell you to taxi to the runway. Before you entered the active runway, you called the tower and they’d give you permission to take the runway and take off. Once airborne, you called Danang DASC, “DASC, Peachbush 10 outbound on Mission 55.” (Resupply) They wanted to know where every aircraft was and what they were doing.”

The HAC flew the mission unless he gave over control so the co-pilot could get flight experience. Most missions were pretty routine. Some became hair-raising.

©2025 William D. Palmer.